| /* |
| * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) |
| * |
| * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| * |
| * Interactivity improvements by Mike Galbraith |
| * (C) 2007 Mike Galbraith <efault@gmx.de> |
| * |
| * Various enhancements by Dmitry Adamushko. |
| * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> |
| * |
| * Group scheduling enhancements by Srivatsa Vaddagiri |
| * Copyright IBM Corporation, 2007 |
| * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> |
| * |
| * Scaled math optimizations by Thomas Gleixner |
| * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> |
| * |
| * Adaptive scheduling granularity, math enhancements by Peter Zijlstra |
| * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
| */ |
| |
| #include <linux/latencytop.h> |
| #include <linux/sched.h> |
| #include <linux/cpumask.h> |
| #include <linux/slab.h> |
| #include <linux/profile.h> |
| #include <linux/interrupt.h> |
| #include <linux/mempolicy.h> |
| #include <linux/migrate.h> |
| #include <linux/task_work.h> |
| |
| #include <trace/events/sched.h> |
| |
| #include "sched.h" |
| |
| /* |
| * Targeted preemption latency for CPU-bound tasks: |
| * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * NOTE: this latency value is not the same as the concept of |
| * 'timeslice length' - timeslices in CFS are of variable length |
| * and have no persistent notion like in traditional, time-slice |
| * based scheduling concepts. |
| * |
| * (to see the precise effective timeslice length of your workload, |
| * run vmstat and monitor the context-switches (cs) field) |
| */ |
| unsigned int sysctl_sched_latency = 6000000ULL; |
| unsigned int normalized_sysctl_sched_latency = 6000000ULL; |
| |
| /* |
| * The initial- and re-scaling of tunables is configurable |
| * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) |
| * |
| * Options are: |
| * SCHED_TUNABLESCALING_NONE - unscaled, always *1 |
| * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) |
| * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus |
| */ |
| enum sched_tunable_scaling sysctl_sched_tunable_scaling |
| = SCHED_TUNABLESCALING_LOG; |
| |
| /* |
| * Minimal preemption granularity for CPU-bound tasks: |
| * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| */ |
| unsigned int sysctl_sched_min_granularity = 750000ULL; |
| unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; |
| |
| /* |
| * is kept at sysctl_sched_latency / sysctl_sched_min_granularity |
| */ |
| static unsigned int sched_nr_latency = 8; |
| |
| /* |
| * After fork, child runs first. If set to 0 (default) then |
| * parent will (try to) run first. |
| */ |
| unsigned int sysctl_sched_child_runs_first __read_mostly; |
| |
| /* |
| * SCHED_OTHER wake-up granularity. |
| * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * This option delays the preemption effects of decoupled workloads |
| * and reduces their over-scheduling. Synchronous workloads will still |
| * have immediate wakeup/sleep latencies. |
| */ |
| unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
| unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; |
| |
| const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
| |
| /* |
| * The exponential sliding window over which load is averaged for shares |
| * distribution. |
| * (default: 10msec) |
| */ |
| unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| /* |
| * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool |
| * each time a cfs_rq requests quota. |
| * |
| * Note: in the case that the slice exceeds the runtime remaining (either due |
| * to consumption or the quota being specified to be smaller than the slice) |
| * we will always only issue the remaining available time. |
| * |
| * default: 5 msec, units: microseconds |
| */ |
| unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; |
| #endif |
| |
| static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
| { |
| lw->weight += inc; |
| lw->inv_weight = 0; |
| } |
| |
| static inline void update_load_sub(struct load_weight *lw, unsigned long dec) |
| { |
| lw->weight -= dec; |
| lw->inv_weight = 0; |
| } |
| |
| static inline void update_load_set(struct load_weight *lw, unsigned long w) |
| { |
| lw->weight = w; |
| lw->inv_weight = 0; |
| } |
| |
| /* |
| * Increase the granularity value when there are more CPUs, |
| * because with more CPUs the 'effective latency' as visible |
| * to users decreases. But the relationship is not linear, |
| * so pick a second-best guess by going with the log2 of the |
| * number of CPUs. |
| * |
| * This idea comes from the SD scheduler of Con Kolivas: |
| */ |
| static int get_update_sysctl_factor(void) |
| { |
| unsigned int cpus = min_t(int, num_online_cpus(), 8); |
| unsigned int factor; |
| |
| switch (sysctl_sched_tunable_scaling) { |
| case SCHED_TUNABLESCALING_NONE: |
| factor = 1; |
| break; |
| case SCHED_TUNABLESCALING_LINEAR: |
| factor = cpus; |
| break; |
| case SCHED_TUNABLESCALING_LOG: |
| default: |
| factor = 1 + ilog2(cpus); |
| break; |
| } |
| |
| return factor; |
| } |
| |
| static void update_sysctl(void) |
| { |
| unsigned int factor = get_update_sysctl_factor(); |
| |
| #define SET_SYSCTL(name) \ |
| (sysctl_##name = (factor) * normalized_sysctl_##name) |
| SET_SYSCTL(sched_min_granularity); |
| SET_SYSCTL(sched_latency); |
| SET_SYSCTL(sched_wakeup_granularity); |
| #undef SET_SYSCTL |
| } |
| |
| void sched_init_granularity(void) |
| { |
| update_sysctl(); |
| } |
| |
| #define WMULT_CONST (~0U) |
| #define WMULT_SHIFT 32 |
| |
| static void __update_inv_weight(struct load_weight *lw) |
| { |
| unsigned long w; |
| |
| if (likely(lw->inv_weight)) |
| return; |
| |
| w = scale_load_down(lw->weight); |
| |
| if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) |
| lw->inv_weight = 1; |
| else if (unlikely(!w)) |
| lw->inv_weight = WMULT_CONST; |
| else |
| lw->inv_weight = WMULT_CONST / w; |
| } |
| |
| /* |
| * delta_exec * weight / lw.weight |
| * OR |
| * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT |
| * |
| * Either weight := NICE_0_LOAD and lw \e prio_to_wmult[], in which case |
| * we're guaranteed shift stays positive because inv_weight is guaranteed to |
| * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. |
| * |
| * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus |
| * weight/lw.weight <= 1, and therefore our shift will also be positive. |
| */ |
| static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
| { |
| u64 fact = scale_load_down(weight); |
| int shift = WMULT_SHIFT; |
| |
| __update_inv_weight(lw); |
| |
| if (unlikely(fact >> 32)) { |
| while (fact >> 32) { |
| fact >>= 1; |
| shift--; |
| } |
| } |
| |
| /* hint to use a 32x32->64 mul */ |
| fact = (u64)(u32)fact * lw->inv_weight; |
| |
| while (fact >> 32) { |
| fact >>= 1; |
| shift--; |
| } |
| |
| return mul_u64_u32_shr(delta_exec, fact, shift); |
| } |
| |
| |
| const struct sched_class fair_sched_class; |
| |
| /************************************************************** |
| * CFS operations on generic schedulable entities: |
| */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| /* cpu runqueue to which this cfs_rq is attached */ |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->rq; |
| } |
| |
| /* An entity is a task if it doesn't "own" a runqueue */ |
| #define entity_is_task(se) (!se->my_q) |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHED_DEBUG |
| WARN_ON_ONCE(!entity_is_task(se)); |
| #endif |
| return container_of(se, struct task_struct, se); |
| } |
| |
| /* Walk up scheduling entities hierarchy */ |
| #define for_each_sched_entity(se) \ |
| for (; se; se = se->parent) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return p->se.cfs_rq; |
| } |
| |
| /* runqueue on which this entity is (to be) queued */ |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| return se->cfs_rq; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return grp->my_q; |
| } |
| |
| static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
| int force_update); |
| |
| static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_rq->on_list) { |
| /* |
| * Ensure we either appear before our parent (if already |
| * enqueued) or force our parent to appear after us when it is |
| * enqueued. The fact that we always enqueue bottom-up |
| * reduces this to two cases. |
| */ |
| if (cfs_rq->tg->parent && |
| cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) { |
| list_add_rcu(&cfs_rq->leaf_cfs_rq_list, |
| &rq_of(cfs_rq)->leaf_cfs_rq_list); |
| } else { |
| list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, |
| &rq_of(cfs_rq)->leaf_cfs_rq_list); |
| } |
| |
| cfs_rq->on_list = 1; |
| /* We should have no load, but we need to update last_decay. */ |
| update_cfs_rq_blocked_load(cfs_rq, 0); |
| } |
| } |
| |
| static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| if (cfs_rq->on_list) { |
| list_del_rcu(&cfs_rq->leaf_cfs_rq_list); |
| cfs_rq->on_list = 0; |
| } |
| } |
| |
| /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) |
| |
| /* Do the two (enqueued) entities belong to the same group ? */ |
| static inline int |
| is_same_group(struct sched_entity *se, struct sched_entity *pse) |
| { |
| if (se->cfs_rq == pse->cfs_rq) |
| return 1; |
| |
| return 0; |
| } |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return se->parent; |
| } |
| |
| /* return depth at which a sched entity is present in the hierarchy */ |
| static inline int depth_se(struct sched_entity *se) |
| { |
| int depth = 0; |
| |
| for_each_sched_entity(se) |
| depth++; |
| |
| return depth; |
| } |
| |
| static void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| int se_depth, pse_depth; |
| |
| /* |
| * preemption test can be made between sibling entities who are in the |
| * same cfs_rq i.e who have a common parent. Walk up the hierarchy of |
| * both tasks until we find their ancestors who are siblings of common |
| * parent. |
| */ |
| |
| /* First walk up until both entities are at same depth */ |
| se_depth = depth_se(*se); |
| pse_depth = depth_se(*pse); |
| |
| while (se_depth > pse_depth) { |
| se_depth--; |
| *se = parent_entity(*se); |
| } |
| |
| while (pse_depth > se_depth) { |
| pse_depth--; |
| *pse = parent_entity(*pse); |
| } |
| |
| while (!is_same_group(*se, *pse)) { |
| *se = parent_entity(*se); |
| *pse = parent_entity(*pse); |
| } |
| } |
| |
| #else /* !CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| return container_of(se, struct task_struct, se); |
| } |
| |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return container_of(cfs_rq, struct rq, cfs); |
| } |
| |
| #define entity_is_task(se) 1 |
| |
| #define for_each_sched_entity(se) \ |
| for (; se; se = NULL) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return &task_rq(p)->cfs; |
| } |
| |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| struct task_struct *p = task_of(se); |
| struct rq *rq = task_rq(p); |
| |
| return &rq->cfs; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return NULL; |
| } |
| |
| static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| } |
| |
| static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| } |
| |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) |
| |
| static inline int |
| is_same_group(struct sched_entity *se, struct sched_entity *pse) |
| { |
| return 1; |
| } |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return NULL; |
| } |
| |
| static inline void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static __always_inline |
| void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
| |
| /************************************************************** |
| * Scheduling class tree data structure manipulation methods: |
| */ |
| |
| static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - max_vruntime); |
| if (delta > 0) |
| max_vruntime = vruntime; |
| |
| return max_vruntime; |
| } |
| |
| static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - min_vruntime); |
| if (delta < 0) |
| min_vruntime = vruntime; |
| |
| return min_vruntime; |
| } |
| |
| static inline int entity_before(struct sched_entity *a, |
| struct sched_entity *b) |
| { |
| return (s64)(a->vruntime - b->vruntime) < 0; |
| } |
| |
| static void update_min_vruntime(struct cfs_rq *cfs_rq) |
| { |
| u64 vruntime = cfs_rq->min_vruntime; |
| |
| if (cfs_rq->curr) |
| vruntime = cfs_rq->curr->vruntime; |
| |
| if (cfs_rq->rb_leftmost) { |
| struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, |
| struct sched_entity, |
| run_node); |
| |
| if (!cfs_rq->curr) |
| vruntime = se->vruntime; |
| else |
| vruntime = min_vruntime(vruntime, se->vruntime); |
| } |
| |
| /* ensure we never gain time by being placed backwards. */ |
| cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
| #ifndef CONFIG_64BIT |
| smp_wmb(); |
| cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; |
| #endif |
| } |
| |
| /* |
| * Enqueue an entity into the rb-tree: |
| */ |
| static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; |
| struct rb_node *parent = NULL; |
| struct sched_entity *entry; |
| int leftmost = 1; |
| |
| /* |
| * Find the right place in the rbtree: |
| */ |
| while (*link) { |
| parent = *link; |
| entry = rb_entry(parent, struct sched_entity, run_node); |
| /* |
| * We dont care about collisions. Nodes with |
| * the same key stay together. |
| */ |
| if (entity_before(se, entry)) { |
| link = &parent->rb_left; |
| } else { |
| link = &parent->rb_right; |
| leftmost = 0; |
| } |
| } |
| |
| /* |
| * Maintain a cache of leftmost tree entries (it is frequently |
| * used): |
| */ |
| if (leftmost) |
| cfs_rq->rb_leftmost = &se->run_node; |
| |
| rb_link_node(&se->run_node, parent, link); |
| rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->rb_leftmost == &se->run_node) { |
| struct rb_node *next_node; |
| |
| next_node = rb_next(&se->run_node); |
| cfs_rq->rb_leftmost = next_node; |
| } |
| |
| rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *left = cfs_rq->rb_leftmost; |
| |
| if (!left) |
| return NULL; |
| |
| return rb_entry(left, struct sched_entity, run_node); |
| } |
| |
| static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
| { |
| struct rb_node *next = rb_next(&se->run_node); |
| |
| if (!next) |
| return NULL; |
| |
| return rb_entry(next, struct sched_entity, run_node); |
| } |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
| |
| if (!last) |
| return NULL; |
| |
| return rb_entry(last, struct sched_entity, run_node); |
| } |
| |
| /************************************************************** |
| * Scheduling class statistics methods: |
| */ |
| |
| int sched_proc_update_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, |
| loff_t *ppos) |
| { |
| int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| int factor = get_update_sysctl_factor(); |
| |
| if (ret || !write) |
| return ret; |
| |
| sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, |
| sysctl_sched_min_granularity); |
| |
| #define WRT_SYSCTL(name) \ |
| (normalized_sysctl_##name = sysctl_##name / (factor)) |
| WRT_SYSCTL(sched_min_granularity); |
| WRT_SYSCTL(sched_latency); |
| WRT_SYSCTL(sched_wakeup_granularity); |
| #undef WRT_SYSCTL |
| |
| return 0; |
| } |
| #endif |
| |
| /* |
| * delta /= w |
| */ |
| static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
| { |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
| |
| return delta; |
| } |
| |
| /* |
| * The idea is to set a period in which each task runs once. |
| * |
| * When there are too many tasks (sched_nr_latency) we have to stretch |
| * this period because otherwise the slices get too small. |
| * |
| * p = (nr <= nl) ? l : l*nr/nl |
| */ |
| static u64 __sched_period(unsigned long nr_running) |
| { |
| u64 period = sysctl_sched_latency; |
| unsigned long nr_latency = sched_nr_latency; |
| |
| if (unlikely(nr_running > nr_latency)) { |
| period = sysctl_sched_min_granularity; |
| period *= nr_running; |
| } |
| |
| return period; |
| } |
| |
| /* |
| * We calculate the wall-time slice from the period by taking a part |
| * proportional to the weight. |
| * |
| * s = p*P[w/rw] |
| */ |
| static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
| |
| for_each_sched_entity(se) { |
| struct load_weight *load; |
| struct load_weight lw; |
| |
| cfs_rq = cfs_rq_of(se); |
| load = &cfs_rq->load; |
| |
| if (unlikely(!se->on_rq)) { |
| lw = cfs_rq->load; |
| |
| update_load_add(&lw, se->load.weight); |
| load = &lw; |
| } |
| slice = __calc_delta(slice, se->load.weight, load); |
| } |
| return slice; |
| } |
| |
| /* |
| * We calculate the vruntime slice of a to-be-inserted task. |
| * |
| * vs = s/w |
| */ |
| static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return calc_delta_fair(sched_slice(cfs_rq, se), se); |
| } |
| |
| #ifdef CONFIG_SMP |
| static unsigned long task_h_load(struct task_struct *p); |
| |
| static inline void __update_task_entity_contrib(struct sched_entity *se); |
| |
| /* Give new task start runnable values to heavy its load in infant time */ |
| void init_task_runnable_average(struct task_struct *p) |
| { |
| u32 slice; |
| |
| p->se.avg.decay_count = 0; |
| slice = sched_slice(task_cfs_rq(p), &p->se) >> 10; |
| p->se.avg.runnable_avg_sum = slice; |
| p->se.avg.runnable_avg_period = slice; |
| __update_task_entity_contrib(&p->se); |
| } |
| #else |
| void init_task_runnable_average(struct task_struct *p) |
| { |
| } |
| #endif |
| |
| /* |
| * Update the current task's runtime statistics. |
| */ |
| static void update_curr(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq->curr; |
| u64 now = rq_clock_task(rq_of(cfs_rq)); |
| u64 delta_exec; |
| |
| if (unlikely(!curr)) |
| return; |
| |
| delta_exec = now - curr->exec_start; |
| if (unlikely((s64)delta_exec <= 0)) |
| return; |
| |
| curr->exec_start = now; |
| |
| schedstat_set(curr->statistics.exec_max, |
| max(delta_exec, curr->statistics.exec_max)); |
| |
| curr->sum_exec_runtime += delta_exec; |
| schedstat_add(cfs_rq, exec_clock, delta_exec); |
| |
| curr->vruntime += calc_delta_fair(delta_exec, curr); |
| update_min_vruntime(cfs_rq); |
| |
| if (entity_is_task(curr)) { |
| struct task_struct *curtask = task_of(curr); |
| |
| trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
| cpuacct_charge(curtask, delta_exec); |
| account_group_exec_runtime(curtask, delta_exec); |
| } |
| |
| account_cfs_rq_runtime(cfs_rq, delta_exec); |
| } |
| |
| static inline void |
| update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq))); |
| } |
| |
| /* |
| * Task is being enqueued - update stats: |
| */ |
| static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * Are we enqueueing a waiting task? (for current tasks |
| * a dequeue/enqueue event is a NOP) |
| */ |
| if (se != cfs_rq->curr) |
| update_stats_wait_start(cfs_rq, se); |
| } |
| |
| static void |
| update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max, |
| rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start)); |
| schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1); |
| schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum + |
| rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
| #ifdef CONFIG_SCHEDSTATS |
| if (entity_is_task(se)) { |
| trace_sched_stat_wait(task_of(se), |
| rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); |
| } |
| #endif |
| schedstat_set(se->statistics.wait_start, 0); |
| } |
| |
| static inline void |
| update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * Mark the end of the wait period if dequeueing a |
| * waiting task: |
| */ |
| if (se != cfs_rq->curr) |
| update_stats_wait_end(cfs_rq, se); |
| } |
| |
| /* |
| * We are picking a new current task - update its stats: |
| */ |
| static inline void |
| update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * We are starting a new run period: |
| */ |
| se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
| } |
| |
| /************************************************** |
| * Scheduling class queueing methods: |
| */ |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| /* |
| * Approximate time to scan a full NUMA task in ms. The task scan period is |
| * calculated based on the tasks virtual memory size and |
| * numa_balancing_scan_size. |
| */ |
| unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
| unsigned int sysctl_numa_balancing_scan_period_max = 60000; |
| |
| /* Portion of address space to scan in MB */ |
| unsigned int sysctl_numa_balancing_scan_size = 256; |
| |
| /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
| unsigned int sysctl_numa_balancing_scan_delay = 1000; |
| |
| /* |
| * After skipping a page migration on a shared page, skip N more numa page |
| * migrations unconditionally. This reduces the number of NUMA migrations |
| * in shared memory workloads, and has the effect of pulling tasks towards |
| * where their memory lives, over pulling the memory towards the task. |
| */ |
| unsigned int sysctl_numa_balancing_migrate_deferred = 16; |
| |
| static unsigned int task_nr_scan_windows(struct task_struct *p) |
| { |
| unsigned long rss = 0; |
| unsigned long nr_scan_pages; |
| |
| /* |
| * Calculations based on RSS as non-present and empty pages are skipped |
| * by the PTE scanner and NUMA hinting faults should be trapped based |
| * on resident pages |
| */ |
| nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); |
| rss = get_mm_rss(p->mm); |
| if (!rss) |
| rss = nr_scan_pages; |
| |
| rss = round_up(rss, nr_scan_pages); |
| return rss / nr_scan_pages; |
| } |
| |
| /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ |
| #define MAX_SCAN_WINDOW 2560 |
| |
| static unsigned int task_scan_min(struct task_struct *p) |
| { |
| unsigned int scan, floor; |
| unsigned int windows = 1; |
| |
| if (sysctl_numa_balancing_scan_size < MAX_SCAN_WINDOW) |
| windows = MAX_SCAN_WINDOW / sysctl_numa_balancing_scan_size; |
| floor = 1000 / windows; |
| |
| scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); |
| return max_t(unsigned int, floor, scan); |
| } |
| |
| static unsigned int task_scan_max(struct task_struct *p) |
| { |
| unsigned int smin = task_scan_min(p); |
| unsigned int smax; |
| |
| /* Watch for min being lower than max due to floor calculations */ |
| smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); |
| return max(smin, smax); |
| } |
| |
| static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
| { |
| rq->nr_numa_running += (p->numa_preferred_nid != -1); |
| rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); |
| } |
| |
| static void account_numa_dequeue(struct rq *rq, struct task_struct *p) |
| { |
| rq->nr_numa_running -= (p->numa_preferred_nid != -1); |
| rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); |
| } |
| |
| struct numa_group { |
| atomic_t refcount; |
| |
| spinlock_t lock; /* nr_tasks, tasks */ |
| int nr_tasks; |
| pid_t gid; |
| struct list_head task_list; |
| |
| struct rcu_head rcu; |
| unsigned long total_faults; |
| unsigned long faults[0]; |
| }; |
| |
| pid_t task_numa_group_id(struct task_struct *p) |
| { |
| return p->numa_group ? p->numa_group->gid : 0; |
| } |
| |
| static inline int task_faults_idx(int nid, int priv) |
| { |
| return 2 * nid + priv; |
| } |
| |
| static inline unsigned long task_faults(struct task_struct *p, int nid) |
| { |
| if (!p->numa_faults) |
| return 0; |
| |
| return p->numa_faults[task_faults_idx(nid, 0)] + |
| p->numa_faults[task_faults_idx(nid, 1)]; |
| } |
| |
| static inline unsigned long group_faults(struct task_struct *p, int nid) |
| { |
| if (!p->numa_group) |
| return 0; |
| |
| return p->numa_group->faults[2*nid] + p->numa_group->faults[2*nid+1]; |
| } |
| |
| /* |
| * These return the fraction of accesses done by a particular task, or |
| * task group, on a particular numa node. The group weight is given a |
| * larger multiplier, in order to group tasks together that are almost |
| * evenly spread out between numa nodes. |
| */ |
| static inline unsigned long task_weight(struct task_struct *p, int nid) |
| { |
| unsigned long total_faults; |
| |
| if (!p->numa_faults) |
| return 0; |
| |
| total_faults = p->total_numa_faults; |
| |
| if (!total_faults) |
| return 0; |
| |
| return 1000 * task_faults(p, nid) / total_faults; |
| } |
| |
| static inline unsigned long group_weight(struct task_struct *p, int nid) |
| { |
| if (!p->numa_group || !p->numa_group->total_faults) |
| return 0; |
| |
| return 1000 * group_faults(p, nid) / p->numa_group->total_faults; |
| } |
| |
| static unsigned long weighted_cpuload(const int cpu); |
| static unsigned long source_load(int cpu, int type); |
| static unsigned long target_load(int cpu, int type); |
| static unsigned long power_of(int cpu); |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg); |
| |
| /* Cached statistics for all CPUs within a node */ |
| struct numa_stats { |
| unsigned long nr_running; |
| unsigned long load; |
| |
| /* Total compute capacity of CPUs on a node */ |
| unsigned long power; |
| |
| /* Approximate capacity in terms of runnable tasks on a node */ |
| unsigned long capacity; |
| int has_capacity; |
| }; |
| |
| /* |
| * XXX borrowed from update_sg_lb_stats |
| */ |
| static void update_numa_stats(struct numa_stats *ns, int nid) |
| { |
| int cpu, cpus = 0; |
| |
| memset(ns, 0, sizeof(*ns)); |
| for_each_cpu(cpu, cpumask_of_node(nid)) { |
| struct rq *rq = cpu_rq(cpu); |
| |
| ns->nr_running += rq->nr_running; |
| ns->load += weighted_cpuload(cpu); |
| ns->power += power_of(cpu); |
| |
| cpus++; |
| } |
| |
| /* |
| * If we raced with hotplug and there are no CPUs left in our mask |
| * the @ns structure is NULL'ed and task_numa_compare() will |
| * not find this node attractive. |
| * |
| * We'll either bail at !has_capacity, or we'll detect a huge imbalance |
| * and bail there. |
| */ |
| if (!cpus) |
| return; |
| |
| ns->load = (ns->load * SCHED_POWER_SCALE) / ns->power; |
| ns->capacity = DIV_ROUND_CLOSEST(ns->power, SCHED_POWER_SCALE); |
| ns->has_capacity = (ns->nr_running < ns->capacity); |
| } |
| |
| struct task_numa_env { |
| struct task_struct *p; |
| |
| int src_cpu, src_nid; |
| int dst_cpu, dst_nid; |
| |
| struct numa_stats src_stats, dst_stats; |
| |
| int imbalance_pct; |
| |
| struct task_struct *best_task; |
| long best_imp; |
| int best_cpu; |
| }; |
| |
| static void task_numa_assign(struct task_numa_env *env, |
| struct task_struct *p, long imp) |
| { |
| if (env->best_task) |
| put_task_struct(env->best_task); |
| if (p) |
| get_task_struct(p); |
| |
| env->best_task = p; |
| env->best_imp = imp; |
| env->best_cpu = env->dst_cpu; |
| } |
| |
| /* |
| * This checks if the overall compute and NUMA accesses of the system would |
| * be improved if the source tasks was migrated to the target dst_cpu taking |
| * into account that it might be best if task running on the dst_cpu should |
| * be exchanged with the source task |
| */ |
| static void task_numa_compare(struct task_numa_env *env, |
| long taskimp, long groupimp) |
| { |
| struct rq *src_rq = cpu_rq(env->src_cpu); |
| struct rq *dst_rq = cpu_rq(env->dst_cpu); |
| struct task_struct *cur; |
| long dst_load, src_load; |
| long load; |
| long imp = (groupimp > 0) ? groupimp : taskimp; |
| |
| rcu_read_lock(); |
| cur = ACCESS_ONCE(dst_rq->curr); |
| if (cur->pid == 0) /* idle */ |
| cur = NULL; |
| |
| /* |
| * "imp" is the fault differential for the source task between the |
| * source and destination node. Calculate the total differential for |
| * the source task and potential destination task. The more negative |
| * the value is, the more rmeote accesses that would be expected to |
| * be incurred if the tasks were swapped. |
| */ |
| if (cur) { |
| /* Skip this swap candidate if cannot move to the source cpu */ |
| if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) |
| goto unlock; |
| |
| /* |
| * If dst and source tasks are in the same NUMA group, or not |
| * in any group then look only at task weights. |
| */ |
| if (cur->numa_group == env->p->numa_group) { |
| imp = taskimp + task_weight(cur, env->src_nid) - |
| task_weight(cur, env->dst_nid); |
| /* |
| * Add some hysteresis to prevent swapping the |
| * tasks within a group over tiny differences. |
| */ |
| if (cur->numa_group) |
| imp -= imp/16; |
| } else { |
| /* |
| * Compare the group weights. If a task is all by |
| * itself (not part of a group), use the task weight |
| * instead. |
| */ |
| if (env->p->numa_group) |
| imp = groupimp; |
| else |
| imp = taskimp; |
| |
| if (cur->numa_group) |
| imp += group_weight(cur, env->src_nid) - |
| group_weight(cur, env->dst_nid); |
| else |
| imp += task_weight(cur, env->src_nid) - |
| task_weight(cur, env->dst_nid); |
| } |
| } |
| |
| if (imp < env->best_imp) |
| goto unlock; |
| |
| if (!cur) { |
| /* Is there capacity at our destination? */ |
| if (env->src_stats.has_capacity && |
| !env->dst_stats.has_capacity) |
| goto unlock; |
| |
| goto balance; |
| } |
| |
| /* Balance doesn't matter much if we're running a task per cpu */ |
| if (src_rq->nr_running == 1 && dst_rq->nr_running == 1) |
| goto assign; |
| |
| /* |
| * In the overloaded case, try and keep the load balanced. |
| */ |
| balance: |
| dst_load = env->dst_stats.load; |
| src_load = env->src_stats.load; |
| |
| /* XXX missing power terms */ |
| load = task_h_load(env->p); |
| dst_load += load; |
| src_load -= load; |
| |
| if (cur) { |
| load = task_h_load(cur); |
| dst_load -= load; |
| src_load += load; |
| } |
| |
| /* make src_load the smaller */ |
| if (dst_load < src_load) |
| swap(dst_load, src_load); |
| |
| if (src_load * env->imbalance_pct < dst_load * 100) |
| goto unlock; |
| |
| assign: |
| task_numa_assign(env, cur, imp); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| static void task_numa_find_cpu(struct task_numa_env *env, |
| long taskimp, long groupimp) |
| { |
| int cpu; |
| |
| for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { |
| /* Skip this CPU if the source task cannot migrate */ |
| if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) |
| continue; |
| |
| env->dst_cpu = cpu; |
| task_numa_compare(env, taskimp, groupimp); |
| } |
| } |
| |
| static int task_numa_migrate(struct task_struct *p) |
| { |
| struct task_numa_env env = { |
| .p = p, |
| |
| .src_cpu = task_cpu(p), |
| .src_nid = task_node(p), |
| |
| .imbalance_pct = 112, |
| |
| .best_task = NULL, |
| .best_imp = 0, |
| .best_cpu = -1 |
| }; |
| struct sched_domain *sd; |
| unsigned long taskweight, groupweight; |
| int nid, ret; |
| long taskimp, groupimp; |
| |
| /* |
| * Pick the lowest SD_NUMA domain, as that would have the smallest |
| * imbalance and would be the first to start moving tasks about. |
| * |
| * And we want to avoid any moving of tasks about, as that would create |
| * random movement of tasks -- counter the numa conditions we're trying |
| * to satisfy here. |
| */ |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
| if (sd) |
| env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; |
| rcu_read_unlock(); |
| |
| /* |
| * Cpusets can break the scheduler domain tree into smaller |
| * balance domains, some of which do not cross NUMA boundaries. |
| * Tasks that are "trapped" in such domains cannot be migrated |
| * elsewhere, so there is no point in (re)trying. |
| */ |
| if (unlikely(!sd)) { |
| p->numa_preferred_nid = cpu_to_node(task_cpu(p)); |
| return -EINVAL; |
| } |
| |
| taskweight = task_weight(p, env.src_nid); |
| groupweight = group_weight(p, env.src_nid); |
| update_numa_stats(&env.src_stats, env.src_nid); |
| env.dst_nid = p->numa_preferred_nid; |
| taskimp = task_weight(p, env.dst_nid) - taskweight; |
| groupimp = group_weight(p, env.dst_nid) - groupweight; |
| update_numa_stats(&env.dst_stats, env.dst_nid); |
| |
| /* If the preferred nid has capacity, try to use it. */ |
| if (env.dst_stats.has_capacity) |
| task_numa_find_cpu(&env, taskimp, groupimp); |
| |
| /* No space available on the preferred nid. Look elsewhere. */ |
| if (env.best_cpu == -1) { |
| for_each_online_node(nid) { |
| if (nid == env.src_nid || nid == p->numa_preferred_nid) |
| continue; |
| |
| /* Only consider nodes where both task and groups benefit */ |
| taskimp = task_weight(p, nid) - taskweight; |
| groupimp = group_weight(p, nid) - groupweight; |
| if (taskimp < 0 && groupimp < 0) |
| continue; |
| |
| env.dst_nid = nid; |
| update_numa_stats(&env.dst_stats, env.dst_nid); |
| task_numa_find_cpu(&env, taskimp, groupimp); |
| } |
| } |
| |
| /* No better CPU than the current one was found. */ |
| if (env.best_cpu == -1) |
| return -EAGAIN; |
| |
| sched_setnuma(p, env.dst_nid); |
| |
| /* |
| * Reset the scan period if the task is being rescheduled on an |
| * alternative node to recheck if the tasks is now properly placed. |
| */ |
| p->numa_scan_period = task_scan_min(p); |
| |
| if (env.best_task == NULL) { |
| int ret = migrate_task_to(p, env.best_cpu); |
| return ret; |
| } |
| |
| ret = migrate_swap(p, env.best_task); |
| put_task_struct(env.best_task); |
| return ret; |
| } |
| |
| /* Attempt to migrate a task to a CPU on the preferred node. */ |
| static void numa_migrate_preferred(struct task_struct *p) |
| { |
| /* This task has no NUMA fault statistics yet */ |
| if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) |
| return; |
| |
| /* Periodically retry migrating the task to the preferred node */ |
| p->numa_migrate_retry = jiffies + HZ; |
| |
| /* Success if task is already running on preferred CPU */ |
| if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid) |
| return; |
| |
| /* Otherwise, try migrate to a CPU on the preferred node */ |
| task_numa_migrate(p); |
| } |
| |
| /* |
| * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS |
| * increments. The more local the fault statistics are, the higher the scan |
| * period will be for the next scan window. If local/remote ratio is below |
| * NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) the |
| * scan period will decrease |
| */ |
| #define NUMA_PERIOD_SLOTS 10 |
| #define NUMA_PERIOD_THRESHOLD 3 |
| |
| /* |
| * Increase the scan period (slow down scanning) if the majority of |
| * our memory is already on our local node, or if the majority of |
| * the page accesses are shared with other processes. |
| * Otherwise, decrease the scan period. |
| */ |
| static void update_task_scan_period(struct task_struct *p, |
| unsigned long shared, unsigned long private) |
| { |
| unsigned int period_slot; |
| int ratio; |
| int diff; |
| |
| unsigned long remote = p->numa_faults_locality[0]; |
| unsigned long local = p->numa_faults_locality[1]; |
| |
| /* |
| * If there were no record hinting faults then either the task is |
| * completely idle or all activity is areas that are not of interest |
| * to automatic numa balancing. Scan slower |
| */ |
| if (local + shared == 0) { |
| p->numa_scan_period = min(p->numa_scan_period_max, |
| p->numa_scan_period << 1); |
| |
| p->mm->numa_next_scan = jiffies + |
| msecs_to_jiffies(p->numa_scan_period); |
| |
| return; |
| } |
| |
| /* |
| * Prepare to scale scan period relative to the current period. |
| * == NUMA_PERIOD_THRESHOLD scan period stays the same |
| * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) |
| * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) |
| */ |
| period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); |
| ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); |
| if (ratio >= NUMA_PERIOD_THRESHOLD) { |
| int slot = ratio - NUMA_PERIOD_THRESHOLD; |
| if (!slot) |
| slot = 1; |
| diff = slot * period_slot; |
| } else { |
| diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; |
| |
| /* |
| * Scale scan rate increases based on sharing. There is an |
| * inverse relationship between the degree of sharing and |
| * the adjustment made to the scanning period. Broadly |
| * speaking the intent is that there is little point |
| * scanning faster if shared accesses dominate as it may |
| * simply bounce migrations uselessly |
| */ |
| period_slot = DIV_ROUND_UP(diff, NUMA_PERIOD_SLOTS); |
| ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared)); |
| diff = (diff * ratio) / NUMA_PERIOD_SLOTS; |
| } |
| |
| p->numa_scan_period = clamp(p->numa_scan_period + diff, |
| task_scan_min(p), task_scan_max(p)); |
| memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
| } |
| |
| static void task_numa_placement(struct task_struct *p) |
| { |
| int seq, nid, max_nid = -1, max_group_nid = -1; |
| unsigned long max_faults = 0, max_group_faults = 0; |
| unsigned long fault_types[2] = { 0, 0 }; |
| spinlock_t *group_lock = NULL; |
| |
| seq = ACCESS_ONCE(p->mm->numa_scan_seq); |
| if (p->numa_scan_seq == seq) |
| return; |
| p->numa_scan_seq = seq; |
| p->numa_scan_period_max = task_scan_max(p); |
| |
| /* If the task is part of a group prevent parallel updates to group stats */ |
| if (p->numa_group) { |
| group_lock = &p->numa_group->lock; |
| spin_lock(group_lock); |
| } |
| |
| /* Find the node with the highest number of faults */ |
| for_each_online_node(nid) { |
| unsigned long faults = 0, group_faults = 0; |
| int priv, i; |
| |
| for (priv = 0; priv < 2; priv++) { |
| long diff; |
| |
| i = task_faults_idx(nid, priv); |
| diff = -p->numa_faults[i]; |
| |
| /* Decay existing window, copy faults since last scan */ |
| p->numa_faults[i] >>= 1; |
| p->numa_faults[i] += p->numa_faults_buffer[i]; |
| fault_types[priv] += p->numa_faults_buffer[i]; |
| p->numa_faults_buffer[i] = 0; |
| |
| faults += p->numa_faults[i]; |
| diff += p->numa_faults[i]; |
| p->total_numa_faults += diff; |
| if (p->numa_group) { |
| /* safe because we can only change our own group */ |
| p->numa_group->faults[i] += diff; |
| p->numa_group->total_faults += diff; |
| group_faults += p->numa_group->faults[i]; |
| } |
| } |
| |
| if (faults > max_faults) { |
| max_faults = faults; |
| max_nid = nid; |
| } |
| |
| if (group_faults > max_group_faults) { |
| max_group_faults = group_faults; |
| max_group_nid = nid; |
| } |
| } |
| |
| update_task_scan_period(p, fault_types[0], fault_types[1]); |
| |
| if (p->numa_group) { |
| /* |
| * If the preferred task and group nids are different, |
| * iterate over the nodes again to find the best place. |
| */ |
| if (max_nid != max_group_nid) { |
| unsigned long weight, max_weight = 0; |
| |
| for_each_online_node(nid) { |
| weight = task_weight(p, nid) + group_weight(p, nid); |
| if (weight > max_weight) { |
| max_weight = weight; |
| max_nid = nid; |
| } |
| } |
| } |
| |
| spin_unlock(group_lock); |
| } |
| |
| /* Preferred node as the node with the most faults */ |
| if (max_faults && max_nid != p->numa_preferred_nid) { |
| /* Update the preferred nid and migrate task if possible */ |
| sched_setnuma(p, max_nid); |
| numa_migrate_preferred(p); |
| } |
| } |
| |
| static inline int get_numa_group(struct numa_group *grp) |
| { |
| return atomic_inc_not_zero(&grp->refcount); |
| } |
| |
| static inline void put_numa_group(struct numa_group *grp) |
| { |
| if (atomic_dec_and_test(&grp->refcount)) |
| kfree_rcu(grp, rcu); |
| } |
| |
| static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
| int *priv) |
| { |
| struct numa_group *grp, *my_grp; |
| struct task_struct *tsk; |
| bool join = false; |
| int cpu = cpupid_to_cpu(cpupid); |
| int i; |
| |
| if (unlikely(!p->numa_group)) { |
| unsigned int size = sizeof(struct numa_group) + |
| 2*nr_node_ids*sizeof(unsigned long); |
| |
| grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); |
| if (!grp) |
| return; |
| |
| atomic_set(&grp->refcount, 1); |
| spin_lock_init(&grp->lock); |
| INIT_LIST_HEAD(&grp->task_list); |
| grp->gid = p->pid; |
| |
| for (i = 0; i < 2*nr_node_ids; i++) |
| grp->faults[i] = p->numa_faults[i]; |
| |
| grp->total_faults = p->total_numa_faults; |
| |
| list_add(&p->numa_entry, &grp->task_list); |
| grp->nr_tasks++; |
| rcu_assign_pointer(p->numa_group, grp); |
| } |
| |
| rcu_read_lock(); |
| tsk = ACCESS_ONCE(cpu_rq(cpu)->curr); |
| |
| if (!cpupid_match_pid(tsk, cpupid)) |
| goto no_join; |
| |
| grp = rcu_dereference(tsk->numa_group); |
| if (!grp) |
| goto no_join; |
| |
| my_grp = p->numa_group; |
| if (grp == my_grp) |
| goto no_join; |
| |
| /* |
| * Only join the other group if its bigger; if we're the bigger group, |
| * the other task will join us. |
| */ |
| if (my_grp->nr_tasks > grp->nr_tasks) |
| goto no_join; |
| |
| /* |
| * Tie-break on the grp address. |
| */ |
| if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) |
| goto no_join; |
| |
| /* Always join threads in the same process. */ |
| if (tsk->mm == current->mm) |
| join = true; |
| |
| /* Simple filter to avoid false positives due to PID collisions */ |
| if (flags & TNF_SHARED) |
| join = true; |
| |
| /* Update priv based on whether false sharing was detected */ |
| *priv = !join; |
| |
| if (join && !get_numa_group(grp)) |
| goto no_join; |
| |
| rcu_read_unlock(); |
| |
| if (!join) |
| return; |
| |
| double_lock(&my_grp->lock, &grp->lock); |
| |
| for (i = 0; i < 2*nr_node_ids; i++) { |
| my_grp->faults[i] -= p->numa_faults[i]; |
| grp->faults[i] += p->numa_faults[i]; |
| } |
| my_grp->total_faults -= p->total_numa_faults; |
| grp->total_faults += p->total_numa_faults; |
| |
| list_move(&p->numa_entry, &grp->task_list); |
| my_grp->nr_tasks--; |
| grp->nr_tasks++; |
| |
| spin_unlock(&my_grp->lock); |
| spin_unlock(&grp->lock); |
| |
| rcu_assign_pointer(p->numa_group, grp); |
| |
| put_numa_group(my_grp); |
| return; |
| |
| no_join: |
| rcu_read_unlock(); |
| return; |
| } |
| |
| void task_numa_free(struct task_struct *p) |
| { |
| struct numa_group *grp = p->numa_group; |
| int i; |
| void *numa_faults = p->numa_faults; |
| |
| if (grp) { |
| spin_lock(&grp->lock); |
| for (i = 0; i < 2*nr_node_ids; i++) |
| grp->faults[i] -= p->numa_faults[i]; |
| grp->total_faults -= p->total_numa_faults; |
| |
| list_del(&p->numa_entry); |
| grp->nr_tasks--; |
| spin_unlock(&grp->lock); |
| rcu_assign_pointer(p->numa_group, NULL); |
| put_numa_group(grp); |
| } |
| |
| p->numa_faults = NULL; |
| p->numa_faults_buffer = NULL; |
| kfree(numa_faults); |
| } |
| |
| /* |
| * Got a PROT_NONE fault for a page on @node. |
| */ |
| void task_numa_fault(int last_cpupid, int node, int pages, int flags) |
| { |
| struct task_struct *p = current; |
| bool migrated = flags & TNF_MIGRATED; |
| int priv; |
| |
| if (!numabalancing_enabled) |
| return; |
| |
| /* for example, ksmd faulting in a user's mm */ |
| if (!p->mm) |
| return; |
| |
| /* Do not worry about placement if exiting */ |
| if (p->state == TASK_DEAD) |
| return; |
| |
| /* Allocate buffer to track faults on a per-node basis */ |
| if (unlikely(!p->numa_faults)) { |
| int size = sizeof(*p->numa_faults) * 2 * nr_node_ids; |
| |
| /* numa_faults and numa_faults_buffer share the allocation */ |
| p->numa_faults = kzalloc(size * 2, GFP_KERNEL|__GFP_NOWARN); |
| if (!p->numa_faults) |
| return; |
| |
| BUG_ON(p->numa_faults_buffer); |
| p->numa_faults_buffer = p->numa_faults + (2 * nr_node_ids); |
| p->total_numa_faults = 0; |
| memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
| } |
| |
| /* |
| * First accesses are treated as private, otherwise consider accesses |
| * to be private if the accessing pid has not changed |
| */ |
| if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { |
| priv = 1; |
| } else { |
| priv = cpupid_match_pid(p, last_cpupid); |
| if (!priv && !(flags & TNF_NO_GROUP)) |
| task_numa_group(p, last_cpupid, flags, &priv); |
| } |
| |
| task_numa_placement(p); |
| |
| /* |
| * Retry task to preferred node migration periodically, in case it |
| * case it previously failed, or the scheduler moved us. |
| */ |
| if (time_after(jiffies, p->numa_migrate_retry)) |
| numa_migrate_preferred(p); |
| |
| if (migrated) |
| p->numa_pages_migrated += pages; |
| |
| p->numa_faults_buffer[task_faults_idx(node, priv)] += pages; |
| p->numa_faults_locality[!!(flags & TNF_FAULT_LOCAL)] += pages; |
| } |
| |
| static void reset_ptenuma_scan(struct task_struct *p) |
| { |
| ACCESS_ONCE(p->mm->numa_scan_seq)++; |
| p->mm->numa_scan_offset = 0; |
| } |
| |
| /* |
| * The expensive part of numa migration is done from task_work context. |
| * Triggered from task_tick_numa(). |
| */ |
| void task_numa_work(struct callback_head *work) |
| { |
| unsigned long migrate, next_scan, now = jiffies; |
| struct task_struct *p = current; |
| struct mm_struct *mm = p->mm; |
| struct vm_area_struct *vma; |
| unsigned long start, end; |
| unsigned long nr_pte_updates = 0; |
| long pages; |
| |
| WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work)); |
| |
| work->next = work; /* protect against double add */ |
| /* |
| * Who cares about NUMA placement when they're dying. |
| * |
| * NOTE: make sure not to dereference p->mm before this check, |
| * exit_task_work() happens _after_ exit_mm() so we could be called |
| * without p->mm even though we still had it when we enqueued this |
| * work. |
| */ |
| if (p->flags & PF_EXITING) |
| return; |
| |
| if (!mm->numa_next_scan) { |
| mm->numa_next_scan = now + |
| msecs_to_jiffies(sysctl_numa_balancing_scan_delay); |
| } |
| |
| /* |
| * Enforce maximal scan/migration frequency.. |
| */ |
| migrate = mm->numa_next_scan; |
| if (time_before(now, migrate)) |
| return; |
| |
| if (p->numa_scan_period == 0) { |
| p->numa_scan_period_max = task_scan_max(p); |
| p->numa_scan_period = task_scan_min(p); |
| } |
| |
| next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
| if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
| return; |
| |
| /* |
| * Delay this task enough that another task of this mm will likely win |
| * the next time around. |
| */ |
| p->node_stamp += 2 * TICK_NSEC; |
| |
| start = mm->numa_scan_offset; |
| pages = sysctl_numa_balancing_scan_size; |
| pages <<= 20 - PAGE_SHIFT; /* MB in pages */ |
| if (!pages) |
| return; |
| |
| down_read(&mm->mmap_sem); |
| vma = find_vma(mm, start); |
| if (!vma) { |
| reset_ptenuma_scan(p); |
| start = 0; |
| vma = mm->mmap; |
| } |
| for (; vma; vma = vma->vm_next) { |
| if (!vma_migratable(vma) || !vma_policy_mof(p, vma)) |
| continue; |
| |
| /* |
| * Shared library pages mapped by multiple processes are not |
| * migrated as it is expected they are cache replicated. Avoid |
| * hinting faults in read-only file-backed mappings or the vdso |
| * as migrating the pages will be of marginal benefit. |
| */ |
| if (!vma->vm_mm || |
| (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) |
| continue; |
| |
| do { |
| start = max(start, vma->vm_start); |
| end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); |
| end = min(end, vma->vm_end); |
| nr_pte_updates += change_prot_numa(vma, start, end); |
| |
| /* |
| * Scan sysctl_numa_balancing_scan_size but ensure that |
| * at least one PTE is updated so that unused virtual |
| * address space is quickly skipped. |
| */ |
| if (nr_pte_updates) |
| pages -= (end - start) >> PAGE_SHIFT; |
| |
| start = end; |
| if (pages <= 0) |
| goto out; |
| } while (end != vma->vm_end); |
| } |
| |
| out: |
| /* |
| * It is possible to reach the end of the VMA list but the last few |
| * VMAs are not guaranteed to the vma_migratable. If they are not, we |
| * would find the !migratable VMA on the next scan but not reset the |
| * scanner to the start so check it now. |
| */ |
| if (vma) |
| mm->numa_scan_offset = start; |
| else |
| reset_ptenuma_scan(p); |
| up_read(&mm->mmap_sem); |
| } |
| |
| /* |
| * Drive the periodic memory faults.. |
| */ |
| void task_tick_numa(struct rq *rq, struct task_struct *curr) |
| { |
| struct callback_head *work = &curr->numa_work; |
| u64 period, now; |
| |
| /* |
| * We don't care about NUMA placement if we don't have memory. |
| */ |
| if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) |
| return; |
| |
| /* |
| * Using runtime rather than walltime has the dual advantage that |
| * we (mostly) drive the selection from busy threads and that the |
| * task needs to have done some actual work before we bother with |
| * NUMA placement. |
| */ |
| now = curr->se.sum_exec_runtime; |
| period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; |
| |
| if (now - curr->node_stamp > period) { |
| if (!curr->node_stamp) |
| curr->numa_scan_period = task_scan_min(curr); |
| curr->node_stamp += period; |
| |
| if (!time_before(jiffies, curr->mm->numa_next_scan)) { |
| init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ |
| task_work_add(curr, work, true); |
| } |
| } |
| } |
| #else |
| static void task_tick_numa(struct rq *rq, struct task_struct *curr) |
| { |
| } |
| |
| static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
| { |
| } |
| |
| static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) |
| { |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| static void |
| account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_add(&cfs_rq->load, se->load.weight); |
| if (!parent_entity(se)) |
| update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
| #ifdef CONFIG_SMP |
| if (entity_is_task(se)) { |
| struct rq *rq = rq_of(cfs_rq); |
| |
| account_numa_enqueue(rq, task_of(se)); |
| list_add(&se->group_node, &rq->cfs_tasks); |
| } |
| #endif |
| cfs_rq->nr_running++; |
| } |
| |
| static void |
| account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_sub(&cfs_rq->load, se->load.weight); |
| if (!parent_entity(se)) |
| update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
| if (entity_is_task(se)) { |
| account_numa_dequeue(rq_of(cfs_rq), task_of(se)); |
| list_del_init(&se->group_node); |
| } |
| cfs_rq->nr_running--; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| # ifdef CONFIG_SMP |
| static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) |
| { |
| long tg_weight; |
| |
| /* |
| * Use this CPU's actual weight instead of the last load_contribution |
| * to gain a more accurate current total weight. See |
| * update_cfs_rq_load_contribution(). |
| */ |
| tg_weight = atomic_long_read(&tg->load_avg); |
| tg_weight -= cfs_rq->tg_load_contrib; |
| tg_weight += cfs_rq->load.weight; |
| |
| return tg_weight; |
| } |
| |
| static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
| { |
| long tg_weight, load, shares; |
| |
| tg_weight = calc_tg_weight(tg, cfs_rq); |
| load = cfs_rq->load.weight; |
| |
| shares = (tg->shares * load); |
| if (tg_weight) |
| shares /= tg_weight; |
| |
| if (shares < MIN_SHARES) |
| shares = MIN_SHARES; |
| if (shares > tg->shares) |
| shares = tg->shares; |
| |
| return shares; |
| } |
| # else /* CONFIG_SMP */ |
| static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
| { |
| return tg->shares; |
| } |
| # endif /* CONFIG_SMP */ |
| static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
| unsigned long weight) |
| { |
| if (se->on_rq) { |
| /* commit outstanding execution time */ |
| if (cfs_rq->curr == se) |
| update_curr(cfs_rq); |
| account_entity_dequeue(cfs_rq, se); |
| } |
| |
| update_load_set(&se->load, weight); |
| |
| if (se->on_rq) |
| account_entity_enqueue(cfs_rq, se); |
| } |
| |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
| |
| static void update_cfs_shares(struct cfs_rq *cfs_rq) |
| { |
| struct task_group *tg; |
| struct sched_entity *se; |
| long shares; |
| |
| tg = cfs_rq->tg; |
| se = tg->se[cpu_of(rq_of(cfs_rq))]; |
| if (!se || throttled_hierarchy(cfs_rq)) |
| return; |
| #ifndef CONFIG_SMP |
| if (likely(se->load.weight == tg->shares)) |
| return; |
| #endif |
| shares = calc_cfs_shares(cfs_rq, tg); |
| |
| reweight_entity(cfs_rq_of(se), se, shares); |
| } |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| static inline void update_cfs_shares(struct cfs_rq *cfs_rq) |
| { |
| } |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| #ifdef CONFIG_SMP |
| /* |
| * We choose a half-life close to 1 scheduling period. |
| * Note: The tables below are dependent on this value. |
| */ |
| #define LOAD_AVG_PERIOD 32 |
| #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ |
| #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */ |
| |
| /* Precomputed fixed inverse multiplies for multiplication by y^n */ |
| static const u32 runnable_avg_yN_inv[] = { |
| 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, |
| 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, |
| 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, |
| 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, |
| 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, |
| 0x85aac367, 0x82cd8698, |
| }; |
| |
| /* |
| * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent |
| * over-estimates when re-combining. |
| */ |
| static const u32 runnable_avg_yN_sum[] = { |
| 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, |
| 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, |
| 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, |
| }; |
| |
| /* |
| * Approximate: |
| * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) |
| */ |
| static __always_inline u64 decay_load(u64 val, u64 n) |
| { |
| unsigned int local_n; |
| |
| if (!n) |
| return val; |
| else if (unlikely(n > LOAD_AVG_PERIOD * 63)) |
| return 0; |
| |
| /* after bounds checking we can collapse to 32-bit */ |
| local_n = n; |
| |
| /* |
| * As y^PERIOD = 1/2, we can combine |
| * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD) |
| * With a look-up table which covers k^n (n<PERIOD) |
| * |
| * To achieve constant time decay_load. |
| */ |
| if (unlikely(local_n >= LOAD_AVG_PERIOD)) { |
| val >>= local_n / LOAD_AVG_PERIOD; |
| local_n %= LOAD_AVG_PERIOD; |
| } |
| |
| val *= runnable_avg_yN_inv[local_n]; |
| /* We don't use SRR here since we always want to round down. */ |
| return val >> 32; |
| } |
| |
| /* |
| * For updates fully spanning n periods, the contribution to runnable |
| * average will be: \Sum 1024*y^n |
| * |
| * We can compute this reasonably efficiently by combining: |
| * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} |
| */ |
| static u32 __compute_runnable_contrib(u64 n) |
| { |
| u32 contrib = 0; |
| |
| if (likely(n <= LOAD_AVG_PERIOD)) |
| return runnable_avg_yN_sum[n]; |
| else if (unlikely(n >= LOAD_AVG_MAX_N)) |
| return LOAD_AVG_MAX; |
| |
| /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */ |
| do { |
| contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */ |
| contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD]; |
| |
| n -= LOAD_AVG_PERIOD; |
| } while (n > LOAD_AVG_PERIOD); |
| |
| contrib = decay_load(contrib, n); |
| return contrib + runnable_avg_yN_sum[n]; |
| } |
| |
| /* |
| * We can represent the historical contribution to runnable average as the |
| * coefficients of a geometric series. To do this we sub-divide our runnable |
| * history into segments of approximately 1ms (1024us); label the segment that |
| * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. |
| * |
| * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... |
| * p0 p1 p2 |
| * (now) (~1ms ago) (~2ms ago) |
| * |
| * Let u_i denote the fraction of p_i that the entity was runnable. |
| * |
| * We then designate the fractions u_i as our co-efficients, yielding the |
| * following representation of historical load: |
| * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... |
| * |
| * We choose y based on the with of a reasonably scheduling period, fixing: |
| * y^32 = 0.5 |
| * |
| * This means that the contribution to load ~32ms ago (u_32) will be weighted |
| * approximately half as much as the contribution to load within the last ms |
| * (u_0). |
| * |
| * When a period "rolls over" and we have new u_0`, multiplying the previous |
| * sum again by y is sufficient to update: |
| * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) |
| * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] |
| */ |
| static __always_inline int __update_entity_runnable_avg(u64 now, |
| struct sched_avg *sa, |
| int runnable) |
| { |
| u64 delta, periods; |
| u32 runnable_contrib; |
| int delta_w, decayed = 0; |
| |
| delta = now - sa->last_runnable_update; |
| /* |
| * This should only happen when time goes backwards, which it |
| * unfortunately does during sched clock init when we swap over to TSC. |
| */ |
| if ((s64)delta < 0) { |
| sa->last_runnable_update = now; |
| return 0; |
| } |
| |
| /* |
| * Use 1024ns as the unit of measurement since it's a reasonable |
| * approximation of 1us and fast to compute. |
| */ |
| delta >>= 10; |
| if (!delta) |
| return 0; |
| sa->last_runnable_update = now; |
| |
| /* delta_w is the amount already accumulated against our next period */ |
| delta_w = sa->runnable_avg_period % 1024; |
| if (delta + delta_w >= 1024) { |
| /* period roll-over */ |
| decayed = 1; |
| |
| /* |
| * Now that we know we're crossing a period boundary, figure |
| * out how much from delta we need to complete the current |
| * period and accrue it. |
| */ |
| delta_w = 1024 - delta_w; |
| if (runnable) |
| sa->runnable_avg_sum += delta_w; |
| sa->runnable_avg_period += delta_w; |
| |
| delta -= delta_w; |
| |
| /* Figure out how many additional periods this update spans */ |
| periods = delta / 1024; |
| delta %= 1024; |
| |
| sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum, |
| periods + 1); |
| sa->runnable_avg_period = decay_load(sa->runnable_avg_period, |
| periods + 1); |
| |
| /* Efficiently calculate \sum (1..n_period) 1024*y^i */ |
| runnable_contrib = __compute_runnable_contrib(periods); |
| if (runnable) |
| sa->runnable_avg_sum += runnable_contrib; |
| sa->runnable_avg_period += runnable_contrib; |
| } |
| |
| /* Remainder of delta accrued against u_0` */ |
| if (runnable) |
| sa->runnable_avg_sum += delta; |
| sa->runnable_avg_period += delta; |
| |
| return decayed; |
| } |
| |
| /* Synchronize an entity's decay with its parenting cfs_rq.*/ |
| static inline u64 __synchronize_entity_decay(struct sched_entity *se) |
| { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 decays = atomic64_read(&cfs_rq->decay_counter); |
| |
| decays -= se->avg.decay_count; |
| if (!decays) |
| return 0; |
| |
| se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays); |
| se->avg.decay_count = 0; |
| |
| return decays; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, |
| int force_update) |
| { |
| struct task_group *tg = cfs_rq->tg; |
| long tg_contrib; |
| |
| tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg; |
| tg_contrib -= cfs_rq->tg_load_contrib; |
| |
| if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) { |
| atomic_long_add(tg_contrib, &tg->load_avg); |
| cfs_rq->tg_load_contrib += tg_contrib; |
| } |
| } |
| |
| /* |
| * Aggregate cfs_rq runnable averages into an equivalent task_group |
| * representation for computing load contributions. |
| */ |
| static inline void __update_tg_runnable_avg(struct sched_avg *sa, |
| struct cfs_rq *cfs_rq) |
| { |
| struct task_group *tg = cfs_rq->tg; |
| long contrib; |
| |
| /* The fraction of a cpu used by this cfs_rq */ |
| contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT, |
| sa->runnable_avg_period + 1); |
| contrib -= cfs_rq->tg_runnable_contrib; |
| |
| if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) { |
| atomic_add(contrib, &tg->runnable_avg); |
| cfs_rq->tg_runnable_contrib += contrib; |
| } |
| } |
| |
| static inline void __update_group_entity_contrib(struct sched_entity *se) |
| { |
| struct cfs_rq *cfs_rq = group_cfs_rq(se); |
| struct task_group *tg = cfs_rq->tg; |
| int runnable_avg; |
| |
| u64 contrib; |
| |
| contrib = cfs_rq->tg_load_contrib * tg->shares; |
| se->avg.load_avg_contrib = div_u64(contrib, |
| atomic_long_read(&tg->load_avg) + 1); |
| |
| /* |
| * For group entities we need to compute a correction term in the case |
| * that they are consuming <1 cpu so that we would contribute the same |
| * load as a task of equal weight. |
| * |
| * Explicitly co-ordinating this measurement would be expensive, but |
| * fortunately the sum of each cpus contribution forms a usable |
| * lower-bound on the true value. |
| * |
| * Consider the aggregate of 2 contributions. Either they are disjoint |
| * (and the sum represents true value) or they are disjoint and we are |
| * understating by the aggregate of their overlap. |
| * |
| * Extending this to N cpus, for a given overlap, the maximum amount we |
| * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of |
| * cpus that overlap for this interval and w_i is the interval width. |
| * |
| * On a small machine; the first term is well-bounded which bounds the |
| * total error since w_i is a subset of the period. Whereas on a |
| * larger machine, while this first term can be larger, if w_i is the |
| * of consequential size guaranteed to see n_i*w_i quickly converge to |
| * our upper bound of 1-cpu. |
| */ |
| runnable_avg = atomic_read(&tg->runnable_avg); |
| if (runnable_avg < NICE_0_LOAD) { |
| se->avg.load_avg_contrib *= runnable_avg; |
| se->avg.load_avg_contrib >>= NICE_0_SHIFT; |
| } |
| } |
| #else |
| static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, |
| int force_update) {} |
| static inline void __update_tg_runnable_avg(struct sched_avg *sa, |
| struct cfs_rq *cfs_rq) {} |
| static inline void __update_group_entity_contrib(struct sched_entity *se) {} |
| #endif |
| |
| static inline void __update_task_entity_contrib(struct sched_entity *se) |
| { |
| u32 contrib; |
| |
| /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */ |
| contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight); |
| contrib /= (se->avg.runnable_avg_period + 1); |
| se->avg.load_avg_contrib = scale_load(contrib); |
| } |
| |
| /* Compute the current contribution to load_avg by se, return any delta */ |
| static long __update_entity_load_avg_contrib(struct sched_entity *se) |
| { |
| long old_contrib = se->avg.load_avg_contrib; |
| |
| if (entity_is_task(se)) { |
| __update_task_entity_contrib(se); |
| } else { |
| __update_tg_runnable_avg(&se->avg, group_cfs_rq(se)); |
| __update_group_entity_contrib(se); |
| } |
| |
| return se->avg.load_avg_contrib - old_contrib; |
| } |
| |
| static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq, |
| long load_contrib) |
| { |
| if (likely(load_contrib < cfs_rq->blocked_load_avg)) |
| cfs_rq->blocked_load_avg -= load_contrib; |
| else |
| cfs_rq->blocked_load_avg = 0; |
| } |
| |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
| |
| /* Update a sched_entity's runnable average */ |
| static inline void update_entity_load_avg(struct sched_entity *se, |
| int update_cfs_rq) |
| { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| long contrib_delta; |
| u64 now; |
| |
| /* |
| * For a group entity we need to use their owned cfs_rq_clock_task() in |
| * case they are the parent of a throttled hierarchy. |
| */ |
| if (entity_is_task(se)) |
| now = cfs_rq_clock_task(cfs_rq); |
| else |
| now = cfs_rq_clock_task(group_cfs_rq(se)); |
| |
| if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq)) |
| return; |
| |
| contrib_delta = __update_entity_load_avg_contrib(se); |
| |
| if (!update_cfs_rq) |
| return; |
| |
| if (se->on_rq) |
| cfs_rq->runnable_load_avg += contrib_delta; |
| else |
| subtract_blocked_load_contrib(cfs_rq, -contrib_delta); |
| } |
| |
| /* |
| * Decay the load contributed by all blocked children and account this so that |
| * their contribution may appropriately discounted when they wake up. |
| */ |
| static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) |
| { |
| u64 now = cfs_rq_clock_task(cfs_rq) >> 20; |
| u64 decays; |
| |
| decays = now - cfs_rq->last_decay; |
| if (!decays && !force_update) |
| return; |
| |
| if (atomic_long_read(&cfs_rq->removed_load)) { |
| unsigned long removed_load; |
| removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0); |
| subtract_blocked_load_contrib(cfs_rq, removed_load); |
| } |
| |
| if (decays) { |
| cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg, |
| decays); |
| atomic64_add(decays, &cfs_rq->decay_counter); |
| cfs_rq->last_decay = now; |
| } |
| |
| __update_cfs_rq_tg_load_contrib(cfs_rq, force_update); |
| } |
| |
| static inline void update_rq_runnable_avg(struct rq *rq, int runnable) |
| { |
| __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable); |
| __update_tg_runnable_avg(&rq->avg, &rq->cfs); |
| } |
| |
| /* Add the load generated by se into cfs_rq's child load-average */ |
| static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, |
| struct sched_entity *se, |
| int wakeup) |
| { |
| /* |
| * We track migrations using entity decay_count <= 0, on a wake-up |
| * migration we use a negative decay count to track the remote decays |
| * accumulated while sleeping. |
| * |
| * Newly forked tasks are enqueued with se->avg.decay_count == 0, they |
| * are seen by enqueue_entity_load_avg() as a migration with an already |
| * constructed load_avg_contrib. |
| */ |
| if (unlikely(se->avg.decay_count <= 0)) { |
| se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq)); |
| if (se->avg.decay_count) { |
| /* |
| * In a wake-up migration we have to approximate the |
| * time sleeping. This is because we can't synchronize |
| * clock_task between the two cpus, and it is not |
| * guaranteed to be read-safe. Instead, we can |
| * approximate this using our carried decays, which are |
| * explicitly atomically readable. |
| */ |
| se->avg.last_runnable_update -= (-se->avg.decay_count) |
| << 20; |
| update_entity_load_avg(se, 0); |
| /* Indicate that we're now synchronized and on-rq */ |
| se->avg.decay_count = 0; |
| } |
| wakeup = 0; |
| } else { |
| /* |
| * Task re-woke on same cpu (or else migrate_task_rq_fair() |
| * would have made count negative); we must be careful to avoid |
| * double-accounting blocked time after synchronizing decays. |
| */ |
| se->avg.last_runnable_update += __synchronize_entity_decay(se) |
| << 20; |
| } |
| |
| /* migrated tasks did not contribute to our blocked load */ |
| if (wakeup) { |
| subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); |
| update_entity_load_avg(se, 0); |
| } |
| |
| cfs_rq->runnable_load_avg += se->avg.load_avg_contrib; |
| /* we force update consideration on load-balancer moves */ |
| update_cfs_rq_blocked_load(cfs_rq, !wakeup); |
| } |
| |
| /* |
| * Remove se's load from this cfs_rq child load-average, if the entity is |
| * transitioning to a blocked state we track its projected decay using |
| * blocked_load_avg. |
| */ |
| static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
| struct sched_entity *se, |
| int sleep) |
| { |
| update_entity_load_avg(se, 1); |
| /* we force update consideration on load-balancer moves */ |
| update_cfs_rq_blocked_load(cfs_rq, !sleep); |
| |
| cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib; |
| if (sleep) { |
| cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; |
| se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); |
| } /* migrations, e.g. sleep=0 leave decay_count == 0 */ |
| } |
| |
| /* |
| * Update the rq's load with the elapsed running time before entering |
| * idle. if the last scheduled task is not a CFS task, idle_enter will |
| * be the only way to update the runnable statistic. |
| */ |
| void idle_enter_fair(struct rq *this_rq) |
| { |
| update_rq_runnable_avg(this_rq, 1); |
| } |
| |
| /* |
| * Update the rq's load with the elapsed idle time before a task is |
| * scheduled. if the newly scheduled task is not a CFS task, idle_exit will |
| * be the only way to update the runnable statistic. |
| */ |
| void idle_exit_fair(struct rq *this_rq) |
| { |
| update_rq_runnable_avg(this_rq, 0); |
| } |
| |
| #else |
| static inline void update_entity_load_avg(struct sched_entity *se, |
| int update_cfs_rq) {} |
| static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} |
| static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, |
| struct sched_entity *se, |
| int wakeup) {} |
| static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, |
| struct sched_entity *se, |
| int sleep) {} |
| static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, |
| int force_update) {} |
| #endif |
| |
| static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHEDSTATS |
| struct task_struct *tsk = NULL; |
| |
| if (entity_is_task(se)) |
| tsk = task_of(se); |
| |
| if (se->statistics.sleep_start) { |
| u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->statistics.sleep_max)) |
| se->statistics.sleep_max = delta; |
| |
| se->statistics.sleep_start = 0; |
| se->statistics.sum_sleep_runtime += delta; |
| |
| if (tsk) { |
| account_scheduler_latency(tsk, delta >> 10, 1); |
| trace_sched_stat_sleep(tsk, delta); |
| } |
| } |
| if (se->statistics.block_start) { |
| u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->statistics.block_max)) |
| se->statistics.block_max = delta; |
| |
| se->statistics.block_start = 0; |
| se->statistics.sum_sleep_runtime += delta; |
| |
| if (tsk) { |
| if (tsk->in_iowait) { |
| se->statistics.iowait_sum += delta; |
| se->statistics.iowait_count++; |
| trace_sched_stat_iowait(tsk, delta); |
| } |
| |
| trace_sched_stat_blocked(tsk, delta); |
| |
| /* |
| * Blocking time is in units of nanosecs, so shift by |
| * 20 to get a milliseconds-range estimation of the |
| * amount of time that the task spent sleeping: |
| */ |
| if (unlikely(prof_on == SLEEP_PROFILING)) { |
| profile_hits(SLEEP_PROFILING, |
| (void *)get_wchan(tsk), |
| delta >> 20); |
| } |
| account_scheduler_latency(tsk, delta >> 10, 0); |
| } |
| } |
| #endif |
| } |
| |
| static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHED_DEBUG |
| s64 d = se->vruntime - cfs_rq->min_vruntime; |
| |
| if (d < 0) |
| d = -d; |
| |
| if (d > 3*sysctl_sched_latency) |
| schedstat_inc(cfs_rq, nr_spread_over); |
| #endif |
| } |
| |
| static void |
| place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) |
| { |
| u64 vruntime = cfs_rq->min_vruntime; |
| |
| /* |
| * The 'current' period is already promised to the current tasks, |
| * however the extra weight of the new task will slow them down a |
| * little, place the new task so that it fits in the slot that |
| * stays open at the end. |
| */ |
| if (initial && sched_feat(START_DEBIT)) |
| vruntime += sched_vslice(cfs_rq, se); |
| |
| /* sleeps up to a single latency don't count. */ |
| if (!initial) { |
| unsigned long thresh = sysctl_sched_latency; |
| |
| /* |
| * Halve their sleep time's effect, to allow |
| * for a gentler effect of sleepers: |
| */ |
| if (sched_feat(GENTLE_FAIR_SLEEPERS)) |
| thresh >>= 1; |
| |
| vruntime -= thresh; |
| } |
| |
| /* ensure we never gain time by being placed backwards. */ |
| se->vruntime = max_vruntime(se->vruntime, vruntime); |
| } |
| |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
| |
| static void |
| enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| /* |
| * Update the normalized vruntime before updating min_vruntime |
| * through calling update_curr(). |
| */ |
| if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) |
| se->vruntime += cfs_rq->min_vruntime; |
| |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP); |
| account_entity_enqueue(cfs_rq, se); |
| update_cfs_shares(cfs_rq); |
| |
| if (flags & ENQUEUE_WAKEUP) { |
| place_entity(cfs_rq, se, 0); |
| enqueue_sleeper(cfs_rq, se); |
| } |
| |
| update_stats_enqueue(cfs_rq, se); |
| check_spread(cfs_rq, se); |
| if (se != cfs_rq->curr) |
| __enqueue_entity(cfs_rq, se); |
| se->on_rq = 1; |
| |
| if (cfs_rq->nr_running == 1) { |
| list_add_leaf_cfs_rq(cfs_rq); |
| check_enqueue_throttle(cfs_rq); |
| } |
| } |
| |
| static void __clear_buddies_last(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->last == se) |
| cfs_rq->last = NULL; |
| else |
| break; |
| } |
| } |
| |
| static void __clear_buddies_next(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->next == se) |
| cfs_rq->next = NULL; |
| else |
| break; |
| } |
| } |
| |
| static void __clear_buddies_skip(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->skip == se) |
| cfs_rq->skip = NULL; |
| else |
| break; |
| } |
| } |
| |
| static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->last == se) |
| __clear_buddies_last(se); |
| |
| if (cfs_rq->next == se) |
| __clear_buddies_next(se); |
| |
| if (cfs_rq->skip == se) |
| __clear_buddies_skip(se); |
| } |
| |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
| |
| static void |
| dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); |
| |
| update_stats_dequeue(cfs_rq, se); |
| if (flags & DEQUEUE_SLEEP) { |
| #ifdef CONFIG_SCHEDSTATS |
| if (entity_is_task(se)) { |
| struct task_struct *tsk = task_of(se); |
| |
| if (tsk->state & TASK_INTERRUPTIBLE) |
| se->statistics.sleep_start = rq_clock(rq_of(cfs_rq)); |
| if (tsk->state & TASK_UNINTERRUPTIBLE) |
| se->statistics.block_start = rq_clock(rq_of(cfs_rq)); |
| } |
| #endif |
| } |
| |
| clear_buddies(cfs_rq, se); |
| |
| if (se != cfs_rq->curr) |
| __dequeue_entity(cfs_rq, se); |
| se->on_rq = 0; |
| account_entity_dequeue(cfs_rq, se); |
| |
| /* |
| * Normalize the entity after updating the min_vruntime because the |
| * update can refer to the ->curr item and we need to reflect this |
| * movement in our normalized position. |
| */ |
| if (!(flags & DEQUEUE_SLEEP)) |
| se->vruntime -= cfs_rq->min_vruntime; |
| |
| /* return excess runtime on last dequeue */ |
| return_cfs_rq_runtime(cfs_rq); |
| |
| update_min_vruntime(cfs_rq); |
| update_cfs_shares(cfs_rq); |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void |
| check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| { |
| unsigned long ideal_runtime, delta_exec; |
| struct sched_entity *se; |
| s64 delta; |
| |
| ideal_runtime = sched_slice(cfs_rq, curr); |
| delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
| if (delta_exec > ideal_runtime) { |
| resched_task(rq_of(cfs_rq)->curr); |
| /* |
| * The current task ran long enough, ensure it doesn't get |
| * re-elected due to buddy favours. |
| */ |
| clear_buddies(cfs_rq, curr); |
| return; |
| } |
| |
| /* |
| * Ensure that a task that missed wakeup preemption by a |
| * narrow margin doesn't have to wait for a full slice. |
| * This also mitigates buddy induced latencies under load. |
| */ |
| if (delta_exec < sysctl_sched_min_granularity) |
| return; |
| |
| se = __pick_first_entity(cfs_rq); |
| delta = curr->vruntime - se->vruntime; |
| |
| if (delta < 0) |
| return; |
| |
| if (delta > ideal_runtime) |
| resched_task(rq_of(cfs_rq)->curr); |
| } |
| |
| static void |
| set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* 'current' is not kept within the tree. */ |
| if (se->on_rq) { |
| /* |
| * Any task has to be enqueued before it get to execute on |
| * a CPU. So account for the time it spent waiting on the |
| * runqueue. |
| */ |
| update_stats_wait_end(cfs_rq, se); |
| __dequeue_entity(cfs_rq, se); |
| } |
| |
| update_stats_curr_start(cfs_rq, se); |
| cfs_rq->curr = se; |
| #ifdef CONFIG_SCHEDSTATS |
| /* |
| * Track our maximum slice length, if the CPU's load is at |
| * least twice that of our own weight (i.e. dont track it |
| * when there are only lesser-weight tasks around): |
| */ |
| if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
| se->statistics.slice_max = max(se->statistics.slice_max, |
| se->sum_exec_runtime - se->prev_sum_exec_runtime); |
| } |
| #endif |
| se->prev_sum_exec_runtime = se->sum_exec_runtime; |
| } |
| |
| static int |
| wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); |
| |
| /* |
| * Pick the next process, keeping these things in mind, in this order: |
| * 1) keep things fair between processes/task groups |
| * 2) pick the "next" process, since someone really wants that to run |
| * 3) pick the "last" process, for cache locality |
| * 4) do not run the "skip" process, if something else is available |
| */ |
| static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *se = __pick_first_entity(cfs_rq); |
| struct sched_entity *left = se; |
| |
| /* |
| * Avoid running the skip buddy, if running something else can |
| * be done without getting too unfair. |
| */ |
| if (cfs_rq->skip == se) { |
| struct sched_entity *second = __pick_next_entity(se); |
| if (second && wakeup_preempt_entity(second, left) < 1) |
| se = second; |
| } |
| |
| /* |
| * Prefer last buddy, try to return the CPU to a preempted task. |
| */ |
| if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) |
| se = cfs_rq->last; |
| |
| /* |
| * Someone really wants this to run. If it's not unfair, run it. |
| */ |
| if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) |
| se = cfs_rq->next; |
| |
| clear_buddies(cfs_rq, se); |
| |
| return se; |
| } |
| |
| static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
| |
| static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
| { |
| /* |
| * If still on the runqueue then deactivate_task() |
| * was not called and update_curr() has to be done: |
| */ |
| if (prev->on_rq) |
| update_curr(cfs_rq); |
| |
| /* throttle cfs_rqs exceeding runtime */ |
| check_cfs_rq_runtime(cfs_rq); |
| |
| check_spread(cfs_rq, prev); |
| if (prev->on_rq) { |
| update_stats_wait_start(cfs_rq, prev); |
| /* Put 'current' back into the tree. */ |
| __enqueue_entity(cfs_rq, prev); |
| /* in !on_rq case, update occurred at dequeue */ |
| update_entity_load_avg(prev, 1); |
| } |
| cfs_rq->curr = NULL; |
| } |
| |
| static void |
| entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| /* |
| * Ensure that runnable average is periodically updated. |
| */ |
| update_entity_load_avg(curr, 1); |
| update_cfs_rq_blocked_load(cfs_rq, 1); |
| update_cfs_shares(cfs_rq); |
| |
| #ifdef CONFIG_SCHED_HRTICK |
| /* |
| * queued ticks are scheduled to match the slice, so don't bother |
| * validating it and just reschedule. |
| */ |
| if (queued) { |
| resched_task(rq_of(cfs_rq)->curr); |
| return; |
| } |
| /* |
| * don't let the period tick interfere with the hrtick preemption |
| */ |
| if (!sched_feat(DOUBLE_TICK) && |
| hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) |
| return; |
| #endif |
| |
| if (cfs_rq->nr_running > 1) |
| check_preempt_tick(cfs_rq, curr); |
| } |
| |
| |
| /************************************************** |
| * CFS bandwidth control machinery |
| */ |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| |
| #ifdef HAVE_JUMP_LABEL |
| static struct static_key __cfs_bandwidth_used; |
| |
| static inline bool cfs_bandwidth_used(void) |
| { |
| return static_key_false(&__cfs_bandwidth_used); |
| } |
| |
| void cfs_bandwidth_usage_inc(void) |
| { |
| static_key_slow_inc(&__cfs_bandwidth_used); |
| } |
| |
| void cfs_bandwidth_usage_dec(void) |
| { |
| static_key_slow_dec(&__cfs_bandwidth_used); |
| } |
| #else /* HAVE_JUMP_LABEL */ |
| static bool cfs_bandwidth_used(void) |
| { |
| return true; |
| } |
| |
| void cfs_bandwidth_usage_inc(void) {} |
| void cfs_bandwidth_usage_dec(void) {} |
| #endif /* HAVE_JUMP_LABEL */ |
| |
| /* |
| * default period for cfs group bandwidth. |
| * default: 0.1s, units: nanoseconds |
| */ |
| static inline u64 default_cfs_period(void) |
| { |
| return 100000000ULL; |
| } |
| |
| static inline u64 sched_cfs_bandwidth_slice(void) |
| { |
| return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; |
| } |
| |
| /* |
| * Replenish runtime according to assigned quota and update expiration time. |
| * We use sched_clock_cpu directly instead of rq->clock to avoid adding |
| * additional synchronization around rq->lock. |
| * |
| * requires cfs_b->lock |
| */ |
| void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
| { |
| u64 now; |
| |
| if (cfs_b->quota == RUNTIME_INF) |
| return; |
| |
| now = sched_clock_cpu(smp_processor_id()); |
| cfs_b->runtime = cfs_b->quota; |
| cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); |
| } |
| |
| static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
| { |
| return &tg->cfs_bandwidth; |
| } |
| |
| /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
| { |
| if (unlikely(cfs_rq->throttle_count)) |
| return cfs_rq->throttled_clock_task; |
| |
| return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
| } |
| |
| /* returns 0 on failure to allocate runtime */ |
| static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct task_group *tg = cfs_rq->tg; |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); |
| u64 amount = 0, min_amount, expires; |
| |
| /* note: this is a positive sum as runtime_remaining <= 0 */ |
| min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (cfs_b->quota == RUNTIME_INF) |
| amount = min_amount; |
| else { |
| /* |
| * If the bandwidth pool has become inactive, then at least one |
| * period must have elapsed since the last consumption. |
| * Refresh the global state and ensure bandwidth timer becomes |
| * active. |
| */ |
| if (!cfs_b->timer_active) { |
| __refill_cfs_bandwidth_runtime(cfs_b); |
| __start_cfs_bandwidth(cfs_b); |
| } |
| |
| if (cfs_b->runtime > 0) { |
| amount = min(cfs_b->runtime, min_amount); |
| cfs_b->runtime -= amount; |
| cfs_b->idle = 0; |
| } |
| } |
| expires = cfs_b->runtime_expires; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| cfs_rq->runtime_remaining += amount; |
| /* |
| * we may have advanced our local expiration to account for allowed |
| * spread between our sched_clock and the one on which runtime was |
| * issued. |
| */ |
| if ((s64)(expires - cfs_rq->runtime_expires) > 0) |
| cfs_rq->runtime_expires = expires; |
| |
| return cfs_rq->runtime_remaining > 0; |
| } |
| |
| /* |
| * Note: This depends on the synchronization provided by sched_clock and the |
| * fact that rq->clock snapshots this value. |
| */ |
| static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| |
| /* if the deadline is ahead of our clock, nothing to do */ |
| if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) |
| return; |
| |
| if (cfs_rq->runtime_remaining < 0) |
| return; |
| |
| /* |
| * If the local deadline has passed we have to consider the |
| * possibility that our sched_clock is 'fast' and the global deadline |
| * has not truly expired. |
| * |
| * Fortunately we can check determine whether this the case by checking |
| * whether the global deadline has advanced. |
| */ |
| |
| if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) { |
| /* extend local deadline, drift is bounded above by 2 ticks */ |
| cfs_rq->runtime_expires += TICK_NSEC; |
| } else { |
| /* global deadline is ahead, expiration has passed */ |
| cfs_rq->runtime_remaining = 0; |
| } |
| } |
| |
| static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
| { |
| /* dock delta_exec before expiring quota (as it could span periods) */ |
| cfs_rq->runtime_remaining -= delta_exec; |
| expire_cfs_rq_runtime(cfs_rq); |
| |
| if (likely(cfs_rq->runtime_remaining > 0)) |
| return; |
| |
| /* |
| * if we're unable to extend our runtime we resched so that the active |
| * hierarchy can be throttled |
| */ |
| if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) |
| resched_task(rq_of(cfs_rq)->curr); |
| } |
| |
| static __always_inline |
| void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
| { |
| if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
| return; |
| |
| __account_cfs_rq_runtime(cfs_rq, delta_exec); |
| } |
| |
| static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
| { |
| return cfs_bandwidth_used() && cfs_rq->throttled; |
| } |
| |
| /* check whether cfs_rq, or any parent, is throttled */ |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) |
| { |
| return cfs_bandwidth_used() && cfs_rq->throttle_count; |
| } |
| |
| /* |
| * Ensure that neither of the group entities corresponding to src_cpu or |
| * dest_cpu are members of a throttled hierarchy when performing group |
| * load-balance operations. |
| */ |
| static inline int throttled_lb_pair(struct task_group *tg, |
| int src_cpu, int dest_cpu) |
| { |
| struct cfs_rq *src_cfs_rq, *dest_cfs_rq; |
| |
| src_cfs_rq = tg->cfs_rq[src_cpu]; |
| dest_cfs_rq = tg->cfs_rq[dest_cpu]; |
| |
| return throttled_hierarchy(src_cfs_rq) || |
| throttled_hierarchy(dest_cfs_rq); |
| } |
| |
| /* updated child weight may affect parent so we have to do this bottom up */ |
| static int tg_unthrottle_up(struct task_group *tg, void *data) |
| { |
| struct rq *rq = data; |
| struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; |
| |
| cfs_rq->throttle_count--; |
| #ifdef CONFIG_SMP |
| if (!cfs_rq->throttle_count) { |
| /* adjust cfs_rq_clock_task() */ |
| cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
| cfs_rq->throttled_clock_task; |
| } |
| #endif |
| |
| return 0; |
| } |
| |
| static int tg_throttle_down(struct task_group *tg, void *data) |
| { |
| struct rq *rq = data; |
| struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; |
| |
| /* group is entering throttled state, stop time */ |
| if (!cfs_rq->throttle_count) |
| cfs_rq->throttled_clock_task = rq_clock_task(rq); |
| cfs_rq->throttle_count++; |
| |
| return 0; |
| } |
| |
| static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| struct sched_entity *se; |
| long task_delta, dequeue = 1; |
| |
| se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; |
| |
| /* freeze hierarchy runnable averages while throttled */ |
| rcu_read_lock(); |
| walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); |
| rcu_read_unlock(); |
| |
| task_delta = cfs_rq->h_nr_running; |
| for_each_sched_entity(se) { |
| struct cfs_rq *qcfs_rq = cfs_rq_of(se); |
| /* throttled entity or throttle-on-deactivate */ |
| if (!se->on_rq) |
| break; |
| |
| if (dequeue) |
| dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); |
| qcfs_rq->h_nr_running -= task_delta; |
| |
| if (qcfs_rq->load.weight) |
| dequeue = 0; |
| } |
| |
| if (!se) |
| rq->nr_running -= task_delta; |
| |
| cfs_rq->throttled = 1; |
| cfs_rq->throttled_clock = rq_clock(rq); |
| raw_spin_lock(&cfs_b->lock); |
| list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); |
| if (!cfs_b->timer_active) |
| __start_cfs_bandwidth(cfs_b); |
| raw_spin_unlock(&cfs_b->lock); |
| } |
| |
| void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| struct sched_entity *se; |
| int enqueue = 1; |
| long task_delta; |
| |
| se = cfs_rq->tg->se[cpu_of(rq)]; |
| |
| cfs_rq->throttled = 0; |
| |
| update_rq_clock(rq); |
| |
| raw_spin_lock(&cfs_b->lock); |
| cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
| list_del_rcu(&cfs_rq->throttled_list); |
| raw_spin_unlock(&cfs_b->lock); |
| |
| /* update hierarchical throttle state */ |
| walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); |
| |
| if (!cfs_rq->load.weight) |
| return; |
| |
| task_delta = cfs_rq->h_nr_running; |
| for_each_sched_entity(se) { |
| if (se->on_rq) |
| enqueue = 0; |
| |
| cfs_rq = cfs_rq_of(se); |
| if (enqueue) |
| enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); |
| cfs_rq->h_nr_running += task_delta; |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| } |
| |
| if (!se) |
| rq->nr_running += task_delta; |
| |
| /* determine whether we need to wake up potentially idle cpu */ |
| if (rq->curr == rq->idle && rq->cfs.nr_running) |
| resched_task(rq->curr); |
| } |
| |
| static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, |
| u64 remaining, u64 expires) |
| { |
| struct cfs_rq *cfs_rq; |
| u64 runtime = remaining; |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, |
| throttled_list) { |
| struct rq *rq = rq_of(cfs_rq); |
| |
| raw_spin_lock(&rq->lock); |
| if (!cfs_rq_throttled(cfs_rq)) |
| goto next; |
| |
| runtime = -cfs_rq->runtime_remaining + 1; |
| if (runtime > remaining) |
| runtime = remaining; |
| remaining -= runtime; |
| |
| cfs_rq->runtime_remaining += runtime; |
| cfs_rq->runtime_expires = expires; |
| |
| /* we check whether we're throttled above */ |
| if (cfs_rq->runtime_remaining > 0) |
| unthrottle_cfs_rq(cfs_rq); |
| |
| next: |
| raw_spin_unlock(&rq->lock); |
| |
| if (!remaining) |
| break; |
| } |
| rcu_read_unlock(); |
| |
| return remaining; |
| } |
| |
| /* |
| * Responsible for refilling a task_group's bandwidth and unthrottling its |
| * cfs_rqs as appropriate. If there has been no activity within the last |
| * period the timer is deactivated until scheduling resumes; cfs_b->idle is |
| * used to track this state. |
| */ |
| static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) |
| { |
| u64 runtime, runtime_expires; |
| int idle = 1, throttled; |
| |
| raw_spin_lock(&cfs_b->lock); |
| /* no need to continue the timer with no bandwidth constraint */ |
| if (cfs_b->quota == RUNTIME_INF) |
| goto out_unlock; |
| |
| throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
| /* idle depends on !throttled (for the case of a large deficit) */ |
| idle = cfs_b->idle && !throttled; |
| cfs_b->nr_periods += overrun; |
| |
| /* if we're going inactive then everything else can be deferred */ |
| if (idle) |
| goto out_unlock; |
| |
| /* |
| * if we have relooped after returning idle once, we need to update our |
| * status as actually running, so that other cpus doing |
| * __start_cfs_bandwidth will stop trying to cancel us. |
| */ |
| cfs_b->timer_active = 1; |
| |
| __refill_cfs_bandwidth_runtime(cfs_b); |
| |
| if (!throttled) { |
| /* mark as potentially idle for the upcoming period */ |
| cfs_b->idle = 1; |
| goto out_unlock; |
| } |
| |
| /* account preceding periods in which throttling occurred */ |
| cfs_b->nr_throttled += overrun; |
| |
| /* |
| * There are throttled entities so we must first use the new bandwidth |
| * to unthrottle them before making it generally available. This |
| * ensures that all existing debts will be paid before a new cfs_rq is |
| * allowed to run. |
| */ |
| runtime = cfs_b->runtime; |
| runtime_expires = cfs_b->runtime_expires; |
| cfs_b->runtime = 0; |
| |
| /* |
| * This check is repeated as we are holding onto the new bandwidth |
| * while we unthrottle. This can potentially race with an unthrottled |
| * group trying to acquire new bandwidth from the global pool. |
| */ |
| while (throttled && runtime > 0) { |
| raw_spin_unlock(&cfs_b->lock); |
| /* we can't nest cfs_b->lock while distributing bandwidth */ |
| runtime = distribute_cfs_runtime(cfs_b, runtime, |
| runtime_expires); |
| raw_spin_lock(&cfs_b->lock); |
| |
| throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
| } |
| |
| /* return (any) remaining runtime */ |
| cfs_b->runtime = runtime; |
| /* |
| * While we are ensured activity in the period following an |
| * unthrottle, this also covers the case in which the new bandwidth is |
| * insufficient to cover the existing bandwidth deficit. (Forcing the |
| * timer to remain active while there are any throttled entities.) |
| */ |
| cfs_b->idle = 0; |
| out_unlock: |
| if (idle) |
| cfs_b->timer_active = 0; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| return idle; |
| } |
| |
| /* a cfs_rq won't donate quota below this amount */ |
| static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; |
| /* minimum remaining period time to redistribute slack quota */ |
| static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; |
| /* how long we wait to gather additional slack before distributing */ |
| static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; |
| |
| /* |
| * Are we near the end of the current quota period? |
| * |
| * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the |
| * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of |
| * migrate_hrtimers, base is never cleared, so we are fine. |
| */ |
| static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
| { |
| struct hrtimer *refresh_timer = &cfs_b->period_timer; |
| u64 remaining; |
| |
| /* if the call-back is running a quota refresh is already occurring */ |
| if (hrtimer_callback_running(refresh_timer)) |
| return 1; |
| |
| /* is a quota refresh about to occur? */ |
| remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); |
| if (remaining < min_expire) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; |
| |
| /* if there's a quota refresh soon don't bother with slack */ |
| if (runtime_refresh_within(cfs_b, min_left)) |
| return; |
| |
| start_bandwidth_timer(&cfs_b->slack_timer, |
| ns_to_ktime(cfs_bandwidth_slack_period)); |
| } |
| |
| /* we know any runtime found here is valid as update_curr() precedes return */ |
| static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; |
| |
| if (slack_runtime <= 0) |
| return; |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (cfs_b->quota != RUNTIME_INF && |
| cfs_rq->runtime_expires == cfs_b->runtime_expires) { |
| cfs_b->runtime += slack_runtime; |
| |
| /* we are under rq->lock, defer unthrottling using a timer */ |
| if (cfs_b->runtime > sched_cfs_bandwidth_slice() && |
| !list_empty(&cfs_b->throttled_cfs_rq)) |
| start_cfs_slack_bandwidth(cfs_b); |
| } |
| raw_spin_unlock(&cfs_b->lock); |
| |
| /* even if it's not valid for return we don't want to try again */ |
| cfs_rq->runtime_remaining -= slack_runtime; |
| } |
| |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
| return; |
| |
| __return_cfs_rq_runtime(cfs_rq); |
| } |
| |
| /* |
| * This is done with a timer (instead of inline with bandwidth return) since |
| * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. |
| */ |
| static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) |
| { |
| u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); |
| u64 expires; |
| |
| /* confirm we're still not at a refresh boundary */ |
| raw_spin_lock(&cfs_b->lock); |
| if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { |
| raw_spin_unlock(&cfs_b->lock); |
| return; |
| } |
| |
| if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) { |
| runtime = cfs_b->runtime; |
| cfs_b->runtime = 0; |
| } |
| expires = cfs_b->runtime_expires; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| if (!runtime) |
| return; |
| |
| runtime = distribute_cfs_runtime(cfs_b, runtime, expires); |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (expires == cfs_b->runtime_expires) |
| cfs_b->runtime = runtime; |
| raw_spin_unlock(&cfs_b->lock); |
| } |
| |
| /* |
| * When a group wakes up we want to make sure that its quota is not already |
| * expired/exceeded, otherwise it may be allowed to steal additional ticks of |
| * runtime as update_curr() throttling can not not trigger until it's on-rq. |
| */ |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| /* an active group must be handled by the update_curr()->put() path */ |
| if (!cfs_rq->runtime_enabled || cfs_rq->curr) |
| return; |
| |
| /* ensure the group is not already throttled */ |
| if (cfs_rq_throttled(cfs_rq)) |
| return; |
| |
| /* update runtime allocation */ |
| account_cfs_rq_runtime(cfs_rq, 0); |
| if (cfs_rq->runtime_remaining <= 0) |
| throttle_cfs_rq(cfs_rq); |
| } |
| |
| /* conditionally throttle active cfs_rq's from put_prev_entity() */ |
| static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
| return; |
| |
| /* |
| * it's possible for a throttled entity to be forced into a running |
| * state (e.g. set_curr_task), in this case we're finished. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| return; |
| |
| throttle_cfs_rq(cfs_rq); |
| } |
| |
| static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
| { |
| struct cfs_bandwidth *cfs_b = |
| container_of(timer, struct cfs_bandwidth, slack_timer); |
| do_sched_cfs_slack_timer(cfs_b); |
| |
| return HRTIMER_NORESTART; |
| } |
| |
| static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) |
| { |
| struct cfs_bandwidth *cfs_b = |
| container_of(timer, struct cfs_bandwidth, period_timer); |
| ktime_t now; |
| int overrun; |
| int idle = 0; |
| |
| for (;;) { |
| now = hrtimer_cb_get_time(timer); |
| overrun = hrtimer_forward(timer, now, cfs_b->period); |
| |
| if (!overrun) |
| break; |
| |
| idle = do_sched_cfs_period_timer(cfs_b, overrun); |
| } |
| |
| return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; |
| } |
| |
| void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| raw_spin_lock_init(&cfs_b->lock); |
| cfs_b->runtime = 0; |
| cfs_b->quota = RUNTIME_INF; |
| cfs_b->period = ns_to_ktime(default_cfs_period()); |
| |
| INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); |
| hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| cfs_b->period_timer.function = sched_cfs_period_timer; |
| hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| cfs_b->slack_timer.function = sched_cfs_slack_timer; |
| } |
| |
| static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| cfs_rq->runtime_enabled = 0; |
| INIT_LIST_HEAD(&cfs_rq->throttled_list); |
| } |
| |
| /* requires cfs_b->lock, may release to reprogram timer */ |
| void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| /* |
| * The timer may be active because we're trying to set a new bandwidth |
| * period or because we're racing with the tear-down path |
| * (timer_active==0 becomes visible before the hrtimer call-back |
| * terminates). In either case we ensure that it's re-programmed |
| */ |
| while (unlikely(hrtimer_active(&cfs_b->period_timer)) && |
| hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) { |
| /* bounce the lock to allow do_sched_cfs_period_timer to run */ |
| raw_spin_unlock(&cfs_b->lock); |
| cpu_relax(); |
| raw_spin_lock(&cfs_b->lock); |
| /* if someone else restarted the timer then we're done */ |
| if (cfs_b->timer_active) |
| return; |
| } |
| |
| cfs_b->timer_active = 1; |
| start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period); |
| } |
| |
| static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| hrtimer_cancel(&cfs_b->period_timer); |
| hrtimer_cancel(&cfs_b->slack_timer); |
| } |
| |
| static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| for_each_leaf_cfs_rq(rq, cfs_rq) { |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| |
| if (!cfs_rq->runtime_enabled) |
| continue; |
| |
| /* |
| * clock_task is not advancing so we just need to make sure |
| * there's some valid quota amount |
| */ |
| cfs_rq->runtime_remaining = cfs_b->quota; |
| if (cfs_rq_throttled(cfs_rq)) |
| unthrottle_cfs_rq(cfs_rq); |
| } |
| } |
| |
| #else /* CONFIG_CFS_BANDWIDTH */ |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
| { |
| return rq_clock_task(rq_of(cfs_rq)); |
| } |
| |
| static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
| static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
| |
| static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
| { |
| return 0; |
| } |
| |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) |
| { |
| return 0; |
| } |
| |
| static inline int throttled_lb_pair(struct task_group *tg, |
| int src_cpu, int dest_cpu) |
| { |
| return 0; |
| } |
| |
| void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
| #endif |
| |
| static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
| { |
| return NULL; |
| } |
| static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} |
| static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
| |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| /************************************************** |
| * CFS operations on tasks: |
| */ |
| |
| #ifdef CONFIG_SCHED_HRTICK |
| static void hrtick_start_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| WARN_ON(task_rq(p) != rq); |
| |
| if (cfs_rq->nr_running > 1) { |
| u64 slice = sched_slice(cfs_rq, se); |
| u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; |
| s64 delta = slice - ran; |
| |
| if (delta < 0) { |
| if (rq->curr == p) |
| resched_task(p); |
| return; |
| } |
| |
| /* |
| * Don't schedule slices shorter than 10000ns, that just |
| * doesn't make sense. Rely on vruntime for fairness. |
| */ |
| if (rq->curr != p) |
| delta = max_t(s64, 10000LL, delta); |
| |
| hrtick_start(rq, delta); |
| } |
| } |
| |
| /* |
| * called from enqueue/dequeue and updates the hrtick when the |
| * current task is from our class and nr_running is low enough |
| * to matter. |
| */ |
| static void hrtick_update(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| |
| if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
| return; |
| |
| if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) |
| hrtick_start_fair(rq, curr); |
| } |
| #else /* !CONFIG_SCHED_HRTICK */ |
| static inline void |
| hrtick_start_fair(struct rq *rq, struct task_struct *p) |
| { |
| } |
| |
| static inline void hrtick_update(struct rq *rq) |
| { |
| } |
| #endif |
| |
| /* |
| * The enqueue_task method is called before nr_running is |
| * increased. Here we update the fair scheduling stats and |
| * then put the task into the rbtree: |
| */ |
| static void |
| enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| |
| for_each_sched_entity(se) { |
| if (se->on_rq) |
| break; |
| cfs_rq = cfs_rq_of(se); |
| enqueue_entity(cfs_rq, se, flags); |
| |
| /* |
| * end evaluation on encountering a throttled cfs_rq |
| * |
| * note: in the case of encountering a throttled cfs_rq we will |
| * post the final h_nr_running increment below. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| cfs_rq->h_nr_running++; |
| |
| flags = ENQUEUE_WAKEUP; |
| } |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_nr_running++; |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| |
| update_cfs_shares(cfs_rq); |
| update_entity_load_avg(se, 1); |
| } |
| |
| if (!se) { |
| update_rq_runnable_avg(rq, rq->nr_running); |
| inc_nr_running(rq); |
| } |
| hrtick_update(rq); |
| } |
| |
| static void set_next_buddy(struct sched_entity *se); |
| |
| /* |
| * The dequeue_task method is called before nr_running is |
| * decreased. We remove the task from the rbtree and |
| * update the fair scheduling stats: |
| */ |
| static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| int task_sleep = flags & DEQUEUE_SLEEP; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| dequeue_entity(cfs_rq, se, flags); |
| |
| /* |
| * end evaluation on encountering a throttled cfs_rq |
| * |
| * note: in the case of encountering a throttled cfs_rq we will |
| * post the final h_nr_running decrement below. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| cfs_rq->h_nr_running--; |
| |
| /* Don't dequeue parent if it has other entities besides us */ |
| if (cfs_rq->load.weight) { |
| /* |
| * Bias pick_next to pick a task from this cfs_rq, as |
| * p is sleeping when it is within its sched_slice. |
| */ |
| if (task_sleep && parent_entity(se)) |
| set_next_buddy(parent_entity(se)); |
| |
| /* avoid re-evaluating load for this entity */ |
| se = parent_entity(se); |
| break; |
| } |
| flags |= DEQUEUE_SLEEP; |
| } |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_nr_running--; |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| |
| update_cfs_shares(cfs_rq); |
| update_entity_load_avg(se, 1); |
| } |
| |
| if (!se) { |
| dec_nr_running(rq); |
| update_rq_runnable_avg(rq, 1); |
| } |
| hrtick_update(rq); |
| } |
| |
| #ifdef CONFIG_SMP |
| /* Used instead of source_load when we know the type == 0 */ |
| static unsigned long weighted_cpuload(const int cpu) |
| { |
| return cpu_rq(cpu)->cfs.runnable_load_avg; |
| } |
| |
| /* |
| * Return a low guess at the load of a migration-source cpu weighted |
| * according to the scheduling class and "nice" value. |
| * |
| * We want to under-estimate the load of migration sources, to |
| * balance conservatively. |
| */ |
| static unsigned long source_load(int cpu, int type) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long total = weighted_cpuload(cpu); |
| |
| if (type == 0 || !sched_feat(LB_BIAS)) |
| return total; |
| |
| return min(rq->cpu_load[type-1], total); |
| } |
| |
| /* |
| * Return a high guess at the load of a migration-target cpu weighted |
| * according to the scheduling class and "nice" value. |
| */ |
| static unsigned long target_load(int cpu, int type) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long total = weighted_cpuload(cpu); |
| |
| if (type == 0 || !sched_feat(LB_BIAS)) |
| return total; |
| |
| return max(rq->cpu_load[type-1], total); |
| } |
| |
| static unsigned long power_of(int cpu) |
| { |
| return cpu_rq(cpu)->cpu_power; |
| } |
| |
| static unsigned long cpu_avg_load_per_task(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long nr_running = ACCESS_ONCE(rq->nr_running); |
| unsigned long load_avg = rq->cfs.runnable_load_avg; |
| |
| if (nr_running) |
| return load_avg / nr_running; |
| |
| return 0; |
| } |
| |
| static void record_wakee(struct task_struct *p) |
| { |
| /* |
| * Rough decay (wiping) for cost saving, don't worry |
| * about the boundary, really active task won't care |
| * about the loss. |
| */ |
| if (jiffies > current->wakee_flip_decay_ts + HZ) { |
| current->wakee_flips = 0; |
| current->wakee_flip_decay_ts = jiffies; |
| } |
| |
| if (current->last_wakee != p) { |
| current->last_wakee = p; |
| current->wakee_flips++; |
| } |
| } |
| |
| static void task_waking_fair(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 min_vruntime; |
| |
| #ifndef CONFIG_64BIT |
| u64 min_vruntime_copy; |
| |
| do { |
| min_vruntime_copy = cfs_rq->min_vruntime_copy; |
| smp_rmb(); |
| min_vruntime = cfs_rq->min_vruntime; |
| } while (min_vruntime != min_vruntime_copy); |
| #else |
| min_vruntime = cfs_rq->min_vruntime; |
| #endif |
| |
| se->vruntime -= min_vruntime; |
| record_wakee(p); |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /* |
| * effective_load() calculates the load change as seen from the root_task_group |
| * |
| * Adding load to a group doesn't make a group heavier, but can cause movement |
| * of group shares between cpus. Assuming the shares were perfectly aligned one |
| * can calculate the shift in shares. |
| * |
| * Calculate the effective load difference if @wl is added (subtracted) to @tg |
| * on this @cpu and results in a total addition (subtraction) of @wg to the |
| * total group weight. |
| * |
| * Given a runqueue weight distribution (rw_i) we can compute a shares |
| * distribution (s_i) using: |
| * |
| * s_i = rw_i / \Sum rw_j (1) |
| * |
| * Suppose we have 4 CPUs and our @tg is a direct child of the root group and |
| * has 7 equal weight tasks, distributed as below (rw_i), with the resulting |
| * shares distribution (s_i): |
| * |
| * rw_i = { 2, 4, 1, 0 } |
| * s_i = { 2/7, 4/7, 1/7, 0 } |
| * |
| * As per wake_affine() we're interested in the load of two CPUs (the CPU the |
| * task used to run on and the CPU the waker is running on), we need to |
| * compute the effect of waking a task on either CPU and, in case of a sync |
| * wakeup, compute the effect of the current task going to sleep. |
| * |
| * So for a change of @wl to the local @cpu with an overall group weight change |
| * of @wl we can compute the new shares distribution (s'_i) using: |
| * |
| * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) |
| * |
| * Suppose we're interested in CPUs 0 and 1, and want to compute the load |
| * differences in waking a task to CPU 0. The additional task changes the |
| * weight and shares distributions like: |
| * |
| * rw'_i = { 3, 4, 1, 0 } |
| * s'_i = { 3/8, 4/8, 1/8, 0 } |
| * |
| * We can then compute the difference in effective weight by using: |
| * |
| * dw_i = S * (s'_i - s_i) (3) |
| * |
| * Where 'S' is the group weight as seen by its parent. |
| * |
| * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) |
| * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - |
| * 4/7) times the weight of the group. |
| */ |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
| { |
| struct sched_entity *se = tg->se[cpu]; |
| |
| if (!tg->parent || !wl) /* the trivial, non-cgroup case */ |
| return wl; |
| |
| for_each_sched_entity(se) { |
| long w, W; |
| |
| tg = se->my_q->tg; |
| |
| /* |
| * W = @wg + \Sum rw_j |
| */ |
| W = wg + calc_tg_weight(tg, se->my_q); |
| |
| /* |
| * w = rw_i + @wl |
| */ |
| w = se->my_q->load.weight + wl; |
| |
| /* |
| * wl = S * s'_i; see (2) |
| */ |
| if (W > 0 && w < W) |
| wl = (w * tg->shares) / W; |
| else |
| wl = tg->shares; |
| |
| /* |
| * Per the above, wl is the new se->load.weight value; since |
| * those are clipped to [MIN_SHARES, ...) do so now. See |
| * calc_cfs_shares(). |
| */ |
| if (wl < MIN_SHARES) |
| wl = MIN_SHARES; |
| |
| /* |
| * wl = dw_i = S * (s'_i - s_i); see (3) |
| */ |
| wl -= se->load.weight; |
| |
| /* |
| * Recursively apply this logic to all parent groups to compute |
| * the final effective load change on the root group. Since |
| * only the @tg group gets extra weight, all parent groups can |
| * only redistribute existing shares. @wl is the shift in shares |
| * resulting from this level per the above. |
| */ |
| wg = 0; |
| } |
| |
| return wl; |
| } |
| #else |
| |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
| { |
| return wl; |
| } |
| |
| #endif |
| |
| static int wake_wide(struct task_struct *p) |
| { |
| int factor = this_cpu_read(sd_llc_size); |
| |
| /* |
| * Yeah, it's the switching-frequency, could means many wakee or |
| * rapidly switch, use factor here will just help to automatically |
| * adjust the loose-degree, so bigger node will lead to more pull. |
| */ |
| if (p->wakee_flips > factor) { |
| /* |
| * wakee is somewhat hot, it needs certain amount of cpu |
| * resource, so if waker is far more hot, prefer to leave |
| * it alone. |
| */ |
| if (current->wakee_flips > (factor * p->wakee_flips)) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) |
| { |
| s64 this_load, load; |
| int idx, this_cpu, prev_cpu; |
| unsigned long tl_per_task; |
| struct task_group *tg; |
| unsigned long weight; |
| int balanced; |
| |
| /* |
| * If we wake multiple tasks be careful to not bounce |
| * ourselves around too much. |
| */ |
| if (wake_wide(p)) |
| return 0; |
| |
| idx = sd->wake_idx; |
| this_cpu = smp_processor_id(); |
| prev_cpu = task_cpu(p); |
| load = source_load(prev_cpu, idx); |
| this_load = target_load(this_cpu, idx); |
| |
| /* |
| * If sync wakeup then subtract the (maximum possible) |
| * effect of the currently running task from the load |
| * of the current CPU: |
| */ |
| if (sync) { |
| tg = task_group(current); |
| weight = current->se.load.weight; |
| |
| this_load += effective_load(tg, this_cpu, -weight, -weight); |
| load += effective_load(tg, prev_cpu, 0, -weight); |
| } |
| |
| tg = task_group(p); |
| weight = p->se.load.weight; |
| |
| /* |
| * In low-load situations, where prev_cpu is idle and this_cpu is idle |
| * due to the sync cause above having dropped this_load to 0, we'll |
| * always have an imbalance, but there's really nothing you can do |
| * about that, so that's good too. |
| * |
| * Otherwise check if either cpus are near enough in load to allow this |
| * task to be woken on this_cpu. |
| */ |
| if (this_load > 0) { |
| s64 this_eff_load, prev_eff_load; |
| |
| this_eff_load = 100; |
| this_eff_load *= power_of(prev_cpu); |
| this_eff_load *= this_load + |
| effective_load(tg, this_cpu, weight, weight); |
| |
| prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; |
| prev_eff_load *= power_of(this_cpu); |
| prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); |
| |
| balanced = this_eff_load <= prev_eff_load; |
| } else |
| balanced = true; |
| |
| /* |
| * If the currently running task will sleep within |
| * a reasonable amount of time then attract this newly |
| * woken task: |
| */ |
| if (sync && balanced) |
| return 1; |
| |
| schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts); |
| tl_per_task = cpu_avg_load_per_task(this_cpu); |
| |
| if (balanced || |
| (this_load <= load && |
| this_load + target_load(prev_cpu, idx) <= tl_per_task)) { |
| /* |
| * This domain has SD_WAKE_AFFINE and |
| * p is cache cold in this domain, and |
| * there is no bad imbalance. |
| */ |
| schedstat_inc(sd, ttwu_move_affine); |
| schedstat_inc(p, se.statistics.nr_wakeups_affine); |
| |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * find_idlest_group finds and returns the least busy CPU group within the |
| * domain. |
| */ |
| static struct sched_group * |
| find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
| int this_cpu, int sd_flag) |
| { |
| struct sched_group *idlest = NULL, *group = sd->groups; |
| unsigned long min_load = ULONG_MAX, this_load = 0; |
| int load_idx = sd->forkexec_idx; |
| int imbalance = 100 + (sd->imbalance_pct-100)/2; |
| |
| if (sd_flag & SD_BALANCE_WAKE) |
| load_idx = sd->wake_idx; |
| |
| do { |
| unsigned long load, avg_load; |
| int local_group; |
| int i; |
| |
| /* Skip over this group if it has no CPUs allowed */ |
| if (!cpumask_intersects(sched_group_cpus(group), |
| tsk_cpus_allowed(p))) |
| continue; |
| |
| local_group = cpumask_test_cpu(this_cpu, |
| sched_group_cpus(group)); |
| |
| /* Tally up the load of all CPUs in the group */ |
| avg_load = 0; |
| |
| for_each_cpu(i, sched_group_cpus(group)) { |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = source_load(i, load_idx); |
| else |
| load = target_load(i, load_idx); |
| |
| avg_load += load; |
| } |
| |
| /* Adjust by relative CPU power of the group */ |
| avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power; |
| |
| if (local_group) { |
| this_load = avg_load; |
| } else if (avg_load < min_load) { |
| min_load = avg_load; |
| idlest = group; |
| } |
| } while (group = group->next, group != sd->groups); |
| |
| if (!idlest || 100*this_load < imbalance*min_load) |
| return NULL; |
| return idlest; |
| } |
| |
| /* |
| * find_idlest_cpu - find the idlest cpu among the cpus in group. |
| */ |
| static int |
| find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) |
| { |
| unsigned long load, min_load = ULONG_MAX; |
| int idlest = -1; |
| int i; |
| |
| /* Traverse only the allowed CPUs */ |
| for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { |
| load = weighted_cpuload(i); |
| |
| if (load < min_load || (load == min_load && i == this_cpu)) { |
| min_load = load; |
| idlest = i; |
| } |
| } |
| |
| return idlest; |
| } |
| |
| /* |
| * Try and locate an idle CPU in the sched_domain. |
| */ |
| static int select_idle_sibling(struct task_struct *p, int target) |
| { |
| struct sched_domain *sd; |
| struct sched_group *sg; |
| int i = task_cpu(p); |
| |
| if (idle_cpu(target)) |
| return target; |
| |
| /* |
| * If the prevous cpu is cache affine and idle, don't be stupid. |
| */ |
| if (i != target && cpus_share_cache(i, target) && idle_cpu(i)) |
| return i; |
| |
| /* |
| * Otherwise, iterate the domains and find an elegible idle cpu. |
| */ |
| sd = rcu_dereference(per_cpu(sd_llc, target)); |
| for_each_lower_domain(sd) { |
| sg = sd->groups; |
| do { |
| if (!cpumask_intersects(sched_group_cpus(sg), |
| tsk_cpus_allowed(p))) |
| goto next; |
| |
| for_each_cpu(i, sched_group_cpus(sg)) { |
| if (i == target || !idle_cpu(i)) |
| goto next; |
| } |
| |
| target = cpumask_first_and(sched_group_cpus(sg), |
| tsk_cpus_allowed(p)); |
| goto done; |
| next: |
| sg = sg->next; |
| } while (sg != sd->groups); |
| } |
| done: |
| return target; |
| } |
| |
| /* |
| * sched_balance_self: balance the current task (running on cpu) in domains |
| * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and |
| * SD_BALANCE_EXEC. |
| * |
| * Balance, ie. select the least loaded group. |
| * |
| * Returns the target CPU number, or the same CPU if no balancing is needed. |
| * |
| * preempt must be disabled. |
| */ |
| static int |
| select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
| { |
| struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
| int cpu = smp_processor_id(); |
| int new_cpu = cpu; |
| int want_affine = 0; |
| int sync = wake_flags & WF_SYNC; |
| |
| if (p->nr_cpus_allowed == 1) |
| return prev_cpu; |
| |
| if (sd_flag & SD_BALANCE_WAKE) { |
| if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
| want_affine = 1; |
| new_cpu = prev_cpu; |
| } |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, tmp) { |
| if (!(tmp->flags & SD_LOAD_BALANCE)) |
| continue; |
| |
| /* |
| * If both cpu and prev_cpu are part of this domain, |
| * cpu is a valid SD_WAKE_AFFINE target. |
| */ |
| if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
| cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { |
| affine_sd = tmp; |
| break; |
| } |
| |
| if (tmp->flags & sd_flag) |
| sd = tmp; |
| } |
| |
| if (affine_sd) { |
| if (cpu != prev_cpu && wake_affine(affine_sd, p, sync)) |
| prev_cpu = cpu; |
| |
| new_cpu = select_idle_sibling(p, prev_cpu); |
| goto unlock; |
| } |
| |
| while (sd) { |
| struct sched_group *group; |
| int weight; |
| |
| if (!(sd->flags & sd_flag)) { |
| sd = sd->child; |
| continue; |
| } |
| |
| group = find_idlest_group(sd, p, cpu, sd_flag); |
| if (!group) { |
| sd = sd->child; |
| continue; |
| } |
| |
| new_cpu = find_idlest_cpu(group, p, cpu); |
| if (new_cpu == -1 || new_cpu == cpu) { |
| /* Now try balancing at a lower domain level of cpu */ |
| sd = sd->child; |
| continue; |
| } |
| |
| /* Now try balancing at a lower domain level of new_cpu */ |
| cpu = new_cpu; |
| weight = sd->span_weight; |
| sd = NULL; |
| for_each_domain(cpu, tmp) { |
| if (weight <= tmp->span_weight) |
| break; |
| if (tmp->flags & sd_flag) |
| sd = tmp; |
| } |
| /* while loop will break here if sd == NULL */ |
| } |
| unlock: |
| rcu_read_unlock(); |
| |
| return new_cpu; |
| } |
| |
| /* |
| * Called immediately before a task is migrated to a new cpu; task_cpu(p) and |
| * cfs_rq_of(p) references at time of call are still valid and identify the |
| * previous cpu. However, the caller only guarantees p->pi_lock is held; no |
| * other assumptions, including the state of rq->lock, should be made. |
| */ |
| static void |
| migrate_task_rq_fair(struct task_struct *p, int next_cpu) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| /* |
| * Load tracking: accumulate removed load so that it can be processed |
| * when we next update owning cfs_rq under rq->lock. Tasks contribute |
| * to blocked load iff they have a positive decay-count. It can never |
| * be negative here since on-rq tasks have decay-count == 0. |
| */ |
| if (se->avg.decay_count) { |
| se->avg.decay_count = -__synchronize_entity_decay(se); |
| atomic_long_add(se->avg.load_avg_contrib, |
| &cfs_rq->removed_load); |
| } |
| } |
| #endif /* CONFIG_SMP */ |
| |
| static unsigned long |
| wakeup_gran(struct sched_entity *curr, struct sched_entity *se) |
| { |
| unsigned long gran = sysctl_sched_wakeup_granularity; |
| |
| /* |
| * Since its curr running now, convert the gran from real-time |
| * to virtual-time in his units. |
| * |
| * By using 'se' instead of 'curr' we penalize light tasks, so |
| * they get preempted easier. That is, if 'se' < 'curr' then |
| * the resulting gran will be larger, therefore penalizing the |
| * lighter, if otoh 'se' > 'curr' then the resulting gran will |
| * be smaller, again penalizing the lighter task. |
| * |
| * This is especially important for buddies when the leftmost |
| * task is higher priority than the buddy. |
| */ |
| return calc_delta_fair(gran, se); |
| } |
| |
| /* |
| * Should 'se' preempt 'curr'. |
| * |
| * |s1 |
| * |s2 |
| * |s3 |
| * g |
| * |<--->|c |
| * |
| * w(c, s1) = -1 |
| * w(c, s2) = 0 |
| * w(c, s3) = 1 |
| * |
| */ |
| static int |
| wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) |
| { |
| s64 gran, vdiff = curr->vruntime - se->vruntime; |
| |
| if (vdiff <= 0) |
| return -1; |
| |
| gran = wakeup_gran(curr, se); |
| if (vdiff > gran) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void set_last_buddy(struct sched_entity *se) |
| { |
| if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
| return; |
| |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->last = se; |
| } |
| |
| static void set_next_buddy(struct sched_entity *se) |
| { |
| if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
| return; |
| |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->next = se; |
| } |
| |
| static void set_skip_buddy(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->skip = se; |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
| { |
| struct task_struct *curr = rq->curr; |
| struct sched_entity *se = &curr->se, *pse = &p->se; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| int scale = cfs_rq->nr_running >= sched_nr_latency; |
| int next_buddy_marked = 0; |
| |
| if (unlikely(se == pse)) |
| return; |
| |
| /* |
| * This is possible from callers such as move_task(), in which we |
| * unconditionally check_prempt_curr() after an enqueue (which may have |
| * lead to a throttle). This both saves work and prevents false |
| * next-buddy nomination below. |
| */ |
| if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) |
| return; |
| |
| if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
| set_next_buddy(pse); |
| next_buddy_marked = 1; |
| } |
| |
| /* |
| * We can come here with TIF_NEED_RESCHED already set from new task |
| * wake up path. |
| * |
| * Note: this also catches the edge-case of curr being in a throttled |
| * group (e.g. via set_curr_task), since update_curr() (in the |
| * enqueue of curr) will have resulted in resched being set. This |
| * prevents us from potentially nominating it as a false LAST_BUDDY |
| * below. |
| */ |
| if (test_tsk_need_resched(curr)) |
| return; |
| |
| /* Idle tasks are by definition preempted by non-idle tasks. */ |
| if (unlikely(curr->policy == SCHED_IDLE) && |
| likely(p->policy != SCHED_IDLE)) |
| goto preempt; |
| |
| /* |
| * Batch and idle tasks do not preempt non-idle tasks (their preemption |
| * is driven by the tick): |
| */ |
| if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
| return; |
| |
| find_matching_se(&se, &pse); |
| update_curr(cfs_rq_of(se)); |
| BUG_ON(!pse); |
| if (wakeup_preempt_entity(se, pse) == 1) { |
| /* |
| * Bias pick_next to pick the sched entity that is |
| * triggering this preemption. |
| */ |
| if (!next_buddy_marked) |
| set_next_buddy(pse); |
| goto preempt; |
| } |
| |
| return; |
| |
| preempt: |
| resched_task(curr); |
| /* |
| * Only set the backward buddy when the current task is still |
| * on the rq. This can happen when a wakeup gets interleaved |
| * with schedule on the ->pre_schedule() or idle_balance() |
| * point, either of which can * drop the rq lock. |
| * |
| * Also, during early boot the idle thread is in the fair class, |
| * for obvious reasons its a bad idea to schedule back to it. |
| */ |
| if (unlikely(!se->on_rq || curr == rq->idle)) |
| return; |
| |
| if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) |
| set_last_buddy(se); |
| } |
| |
| static struct task_struct *pick_next_task_fair(struct rq *rq) |
| { |
| struct task_struct *p; |
| struct cfs_rq *cfs_rq = &rq->cfs; |
| struct sched_entity *se; |
| |
| if (!cfs_rq->nr_running) |
| return NULL; |
| |
| do { |
| se = pick_next_entity(cfs_rq); |
| set_next_entity(cfs_rq, se); |
| cfs_rq = group_cfs_rq(se); |
| } while (cfs_rq); |
| |
| p = task_of(se); |
| if (hrtick_enabled(rq)) |
| hrtick_start_fair(rq, p); |
| |
| return p; |
| } |
| |
| /* |
| * Account for a descheduled task: |
| */ |
| static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
| { |
| struct sched_entity *se = &prev->se; |
| struct cfs_rq *cfs_rq; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| put_prev_entity(cfs_rq, se); |
| } |
| } |
| |
| /* |
| * sched_yield() is very simple |
| * |
| * The magic of dealing with the ->skip buddy is in pick_next_entity. |
| */ |
| static void yield_task_fair(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| struct sched_entity *se = &curr->se; |
| |
| /* |
| * Are we the only task in the tree? |
| */ |
| if (unlikely(rq->nr_running == 1)) |
| return; |
| |
| clear_buddies(cfs_rq, se); |
| |
| if (curr->policy != SCHED_BATCH) { |
| update_rq_clock(rq); |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| /* |
| * Tell update_rq_clock() that we've just updated, |
| * so we don't do microscopic update in schedule() |
| * and double the fastpath cost. |
| */ |
| rq->skip_clock_update = 1; |
| } |
| |
| set_skip_buddy(se); |
| } |
| |
| static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
| { |
| struct sched_entity *se = &p->se; |
| |
| /* throttled hierarchies are not runnable */ |
| if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) |
| return false; |
| |
| /* Tell the scheduler that we'd really like pse to run next. */ |
| set_next_buddy(se); |
| |
| yield_task_fair(rq); |
| |
| return true; |
| } |
| |
| #ifdef CONFIG_SMP |
| /************************************************** |
| * Fair scheduling class load-balancing methods. |
| * |
| * BASICS |
| * |
| * The purpose of load-balancing is to achieve the same basic fairness the |
| * per-cpu scheduler provides, namely provide a proportional amount of compute |
| * time to each task. This is expressed in the following equation: |
| * |
| * W_i,n/P_i == W_j,n/P_j for all i,j (1) |
| * |
| * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight |
| * W_i,0 is defined as: |
| * |
| * W_i,0 = \Sum_j w_i,j (2) |
| * |
| * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight |
| * is derived from the nice value as per prio_to_weight[]. |
| * |
| * The weight average is an exponential decay average of the instantaneous |
| * weight: |
| * |
| * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) |
| * |
| * P_i is the cpu power (or compute capacity) of cpu i, typically it is the |
| * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
| * can also include other factors [XXX]. |
| * |
| * To achieve this balance we define a measure of imbalance which follows |
| * directly from (1): |
| * |
| * imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j } (4) |
| * |
| * We them move tasks around to minimize the imbalance. In the continuous |
| * function space it is obvious this converges, in the discrete case we get |
| * a few fun cases generally called infeasible weight scenarios. |
| * |
| * [XXX expand on: |
| * - infeasible weights; |
| * - local vs global optima in the discrete case. ] |
| * |
| * |
| * SCHED DOMAINS |
| * |
| * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) |
| * for all i,j solution, we create a tree of cpus that follows the hardware |
| * topology where each level pairs two lower groups (or better). This results |
| * in O(log n) layers. Furthermore we reduce the number of cpus going up the |
| * tree to only the first of the previous level and we decrease the frequency |
| * of load-balance at each level inv. proportional to the number of cpus in |
| * the groups. |
| * |
| * This yields: |
| * |
| * log_2 n 1 n |
| * \Sum { --- * --- * 2^i } = O(n) (5) |
| * i = 0 2^i 2^i |
| * `- size of each group |
| * | | `- number of cpus doing load-balance |
| * | `- freq |
| * `- sum over all levels |
| * |
| * Coupled with a limit on how many tasks we can migrate every balance pass, |
| * this makes (5) the runtime complexity of the balancer. |
| * |
| * An important property here is that each CPU is still (indirectly) connected |
| * to every other cpu in at most O(log n) steps: |
| * |
| * The adjacency matrix of the resulting graph is given by: |
| * |
| * log_2 n |
| * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) |
| * k = 0 |
| * |
| * And you'll find that: |
| * |
| * A^(log_2 n)_i,j != 0 for all i,j (7) |
| * |
| * Showing there's indeed a path between every cpu in at most O(log n) steps. |
| * The task movement gives a factor of O(m), giving a convergence complexity |
| * of: |
| * |
| * O(nm log n), n := nr_cpus, m := nr_tasks (8) |
| * |
| * |
| * WORK CONSERVING |
| * |
| * In order to avoid CPUs going idle while there's still work to do, new idle |
| * balancing is more aggressive and has the newly idle cpu iterate up the domain |
| * tree itself instead of relying on other CPUs to bring it work. |
| * |
| * This adds some complexity to both (5) and (8) but it reduces the total idle |
| * time. |
| * |
| * [XXX more?] |
| * |
| * |
| * CGROUPS |
| * |
| * Cgroups make a horror show out of (2), instead of a simple sum we get: |
| * |
| * s_k,i |
| * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) |
| * S_k |
| * |
| * Where |
| * |
| * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) |
| * |
| * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. |
| * |
| * The big problem is S_k, its a global sum needed to compute a local (W_i) |
| * property. |
| * |
| * [XXX write more on how we solve this.. _after_ merging pjt's patches that |
| * rewrite all of this once again.] |
| */ |
| |
| static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
| |
| enum fbq_type { regular, remote, all }; |
| |
| #define LBF_ALL_PINNED 0x01 |
| #define LBF_NEED_BREAK 0x02 |
| #define LBF_DST_PINNED 0x04 |
| #define LBF_SOME_PINNED 0x08 |
| |
| struct lb_env { |
| struct sched_domain *sd; |
| |
| struct rq *src_rq; |
| int src_cpu; |
| |
| int dst_cpu; |
| struct rq *dst_rq; |
| |
| struct cpumask *dst_grpmask; |
| int new_dst_cpu; |
| enum cpu_idle_type idle; |
| long imbalance; |
| /* The set of CPUs under consideration for load-balancing */ |
| struct cpumask *cpus; |
| |
| unsigned int flags; |
| |
| unsigned int loop; |
| unsigned int loop_break; |
| unsigned int loop_max; |
| |
| enum fbq_type fbq_type; |
| }; |
| |
| /* |
| * move_task - move a task from one runqueue to another runqueue. |
| * Both runqueues must be locked. |
| */ |
| static void move_task(struct task_struct *p, struct lb_env *env) |
| { |
| deactivate_task(env->src_rq, p, 0); |
| set_task_cpu(p, env->dst_cpu); |
| activate_task(env->dst_rq, p, 0); |
| check_preempt_curr(env->dst_rq, p, 0); |
| } |
| |
| /* |
| * Is this task likely cache-hot: |
| */ |
| static int |
| task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) |
| { |
| s64 delta; |
| |
| if (p->sched_class != &fair_sched_class) |
| return 0; |
| |
| if (unlikely(p->policy == SCHED_IDLE)) |
| return 0; |
| |
| /* |
| * Buddy candidates are cache hot: |
| */ |
| if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running && |
| (&p->se == cfs_rq_of(&p->se)->next || |
| &p->se == cfs_rq_of(&p->se)->last)) |
| return 1; |
| |
| if (sysctl_sched_migration_cost == -1) |
| return 1; |
| if (sysctl_sched_migration_cost == 0) |
| return 0; |
| |
| delta = now - p->se.exec_start; |
| |
| return delta < (s64)sysctl_sched_migration_cost; |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| /* Returns true if the destination node has incurred more faults */ |
| static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) |
| { |
| int src_nid, dst_nid; |
| |
| if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults || |
| !(env->sd->flags & SD_NUMA)) { |
| return false; |
| } |
| |
| src_nid = cpu_to_node(env->src_cpu); |
| dst_nid = cpu_to_node(env->dst_cpu); |
| |
| if (src_nid == dst_nid) |
| return false; |
| |
| /* Always encourage migration to the preferred node. */ |
| if (dst_nid == p->numa_preferred_nid) |
| return true; |
| |
| /* If both task and group weight improve, this move is a winner. */ |
| if (task_weight(p, dst_nid) > task_weight(p, src_nid) && |
| group_weight(p, dst_nid) > group_weight(p, src_nid)) |
| return true; |
| |
| return false; |
| } |
| |
| |
| static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) |
| { |
| int src_nid, dst_nid; |
| |
| if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER)) |
| return false; |
| |
| if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) |
| return false; |
| |
| src_nid = cpu_to_node(env->src_cpu); |
| dst_nid = cpu_to_node(env->dst_cpu); |
| |
| if (src_nid == dst_nid) |
| return false; |
| |
| /* Migrating away from the preferred node is always bad. */ |
| if (src_nid == p->numa_preferred_nid) |
| return true; |
| |
| /* If either task or group weight get worse, don't do it. */ |
| if (task_weight(p, dst_nid) < task_weight(p, src_nid) || |
| group_weight(p, dst_nid) < group_weight(p, src_nid)) |
| return true; |
| |
| return false; |
| } |
| |
| #else |
| static inline bool migrate_improves_locality(struct task_struct *p, |
| struct lb_env *env) |
| { |
| return false; |
| } |
| |
| static inline bool migrate_degrades_locality(struct task_struct *p, |
| struct lb_env *env) |
| { |
| return false; |
| } |
| #endif |
| |
| /* |
| * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? |
| */ |
| static |
| int can_migrate_task(struct task_struct *p, struct lb_env *env) |
| { |
| int tsk_cache_hot = 0; |
| /* |
| * We do not migrate tasks that are: |
| * 1) throttled_lb_pair, or |
| * 2) cannot be migrated to this CPU due to cpus_allowed, or |
| * 3) running (obviously), or |
| * 4) are cache-hot on their current CPU. |
| */ |
| if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
| return 0; |
| |
| if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { |
| int cpu; |
| |
| schedstat_inc(p, se.statistics.nr_failed_migrations_affine); |
| |
| env->flags |= LBF_SOME_PINNED; |
| |
| /* |
| * Remember if this task can be migrated to any other cpu in |
| * our sched_group. We may want to revisit it if we couldn't |
| * meet load balance goals by pulling other tasks on src_cpu. |
| * |
| * Also avoid computing new_dst_cpu if we have already computed |
| * one in current iteration. |
| */ |
| if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) |
| return 0; |
| |
| /* Prevent to re-select dst_cpu via env's cpus */ |
| for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { |
| if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { |
| env->flags |= LBF_DST_PINNED; |
| env->new_dst_cpu = cpu; |
| break; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* Record that we found atleast one task that could run on dst_cpu */ |
| env->flags &= ~LBF_ALL_PINNED; |
| |
| if (task_running(env->src_rq, p)) { |
| schedstat_inc(p, se.statistics.nr_failed_migrations_running); |
| return 0; |
| } |
| |
| /* |
| * Aggressive migration if: |
| * 1) destination numa is preferred |
| * 2) task is cache cold, or |
| * 3) too many balance attempts have failed. |
| */ |
| tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd); |
| if (!tsk_cache_hot) |
| tsk_cache_hot = migrate_degrades_locality(p, env); |
| |
| if (migrate_improves_locality(p, env)) { |
| #ifdef CONFIG_SCHEDSTATS |
| if (tsk_cache_hot) { |
| schedstat_inc(env->sd, lb_hot_gained[env->idle]); |
| schedstat_inc(p, se.statistics.nr_forced_migrations); |
| } |
| #endif |
| return 1; |
| } |
| |
| if (!tsk_cache_hot || |
| env->sd->nr_balance_failed > env->sd->cache_nice_tries) { |
| |
| if (tsk_cache_hot) { |
| schedstat_inc(env->sd, lb_hot_gained[env->idle]); |
| schedstat_inc(p, se.statistics.nr_forced_migrations); |
| } |
| |
| return 1; |
| } |
| |
| schedstat_inc(p, se.statistics.nr_failed_migrations_hot); |
| return 0; |
| } |
| |
| /* |
| * move_one_task tries to move exactly one task from busiest to this_rq, as |
| * part of active balancing operations within "domain". |
| * Returns 1 if successful and 0 otherwise. |
| * |
| * Called with both runqueues locked. |
| */ |
| static int move_one_task(struct lb_env *env) |
| { |
| struct task_struct *p, *n; |
| |
| list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { |
| if (!can_migrate_task(p, env)) |
| continue; |
| |
| move_task(p, env); |
| /* |
| * Right now, this is only the second place move_task() |
| * is called, so we can safely collect move_task() |
| * stats here rather than inside move_task(). |
| */ |
| schedstat_inc(env->sd, lb_gained[env->idle]); |
| return 1; |
| } |
| return 0; |
| } |
| |
| static const unsigned int sched_nr_migrate_break = 32; |
| |
| /* |
| * move_tasks tries to move up to imbalance weighted load from busiest to |
| * this_rq, as part of a balancing operation within domain "sd". |
| * Returns 1 if successful and 0 otherwise. |
| * |
| * Called with both runqueues locked. |
| */ |
| static int move_tasks(struct lb_env *env) |
| { |
| struct list_head *tasks = &env->src_rq->cfs_tasks; |
| struct task_struct *p; |
| unsigned long load; |
| int pulled = 0; |
| |
| if (env->imbalance <= 0) |
| return 0; |
| |
| while (!list_empty(tasks)) { |
| p = list_first_entry(tasks, struct task_struct, se.group_node); |
| |
| env->loop++; |
| /* We've more or less seen every task there is, call it quits */ |
| if (env->loop > env->loop_max) |
| break; |
| |
| /* take a breather every nr_migrate tasks */ |
| if (env->loop > env->loop_break) { |
| env->loop_break += sched_nr_migrate_break; |
| env->flags |= LBF_NEED_BREAK; |
| break; |
| } |
| |
| if (!can_migrate_task(p, env)) |
| goto next; |
| |
| load = task_h_load(p); |
| |
| if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
| goto next; |
| |
| if ((load / 2) > env->imbalance) |
| goto next; |
| |
| move_task(p, env); |
| pulled++; |
| env->imbalance -= load; |
| |
| #ifdef CONFIG_PREEMPT |
| /* |
| * NEWIDLE balancing is a source of latency, so preemptible |
| * kernels will stop after the first task is pulled to minimize |
| * the critical section. |
| */ |
| if (env->idle == CPU_NEWLY_IDLE) |
| break; |
| #endif |
| |
| /* |
| * We only want to steal up to the prescribed amount of |
| * weighted load. |
| */ |
| if (env->imbalance <= 0) |
| break; |
| |
| continue; |
| next: |
| list_move_tail(&p->se.group_node, tasks); |
| } |
| |
| /* |
| * Right now, this is one of only two places move_task() is called, |
| * so we can safely collect move_task() stats here rather than |
| * inside move_task(). |
| */ |
| schedstat_add(env->sd, lb_gained[env->idle], pulled); |
| |
| return pulled; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /* |
| * update tg->load_weight by folding this cpu's load_avg |
| */ |
| static void __update_blocked_averages_cpu(struct task_group *tg, int cpu) |
| { |
| struct sched_entity *se = tg->se[cpu]; |
| struct cfs_rq *cfs_rq = tg->cfs_rq[cpu]; |
| |
| /* throttled entities do not contribute to load */ |
| if (throttled_hierarchy(cfs_rq)) |
| return; |
| |
| update_cfs_rq_blocked_load(cfs_rq, 1); |
| |
| if (se) { |
| update_entity_load_avg(se, 1); |
| /* |
| * We pivot on our runnable average having decayed to zero for |
| * list removal. This generally implies that all our children |
| * have also been removed (modulo rounding error or bandwidth |
| * control); however, such cases are rare and we can fix these |
| * at enqueue. |
| * |
| * TODO: fix up out-of-order children on enqueue. |
| */ |
| if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running) |
| list_del_leaf_cfs_rq(cfs_rq); |
| } else { |
| struct rq *rq = rq_of(cfs_rq); |
| update_rq_runnable_avg(rq, rq->nr_running); |
| } |
| } |
| |
| static void update_blocked_averages(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct cfs_rq *cfs_rq; |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| update_rq_clock(rq); |
| /* |
| * Iterates the task_group tree in a bottom up fashion, see |
| * list_add_leaf_cfs_rq() for details. |
| */ |
| for_each_leaf_cfs_rq(rq, cfs_rq) { |
| /* |
| * Note: We may want to consider periodically releasing |
| * rq->lock about these updates so that creating many task |
| * groups does not result in continually extending hold time. |
| */ |
| __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); |
| } |
| |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| /* |
| * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
| * This needs to be done in a top-down fashion because the load of a child |
| * group is a fraction of its parents load. |
| */ |
| static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; |
| unsigned long now = jiffies; |
| unsigned long load; |
| |
| if (cfs_rq->last_h_load_update == now) |
| return; |
| |
| cfs_rq->h_load_next = NULL; |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_load_next = se; |
| if (cfs_rq->last_h_load_update == now) |
| break; |
| } |
| |
| if (!se) { |
| cfs_rq->h_load = cfs_rq->runnable_load_avg; |
| cfs_rq->last_h_load_update = now; |
| } |
| |
| while ((se = cfs_rq->h_load_next) != NULL) { |
| load = cfs_rq->h_load; |
| load = div64_ul(load * se->avg.load_avg_contrib, |
| cfs_rq->runnable_load_avg + 1); |
| cfs_rq = group_cfs_rq(se); |
| cfs_rq->h_load = load; |
| cfs_rq->last_h_load_update = now; |
| } |
| } |
| |
| static unsigned long task_h_load(struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(p); |
| |
| update_cfs_rq_h_load(cfs_rq); |
| return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load, |
| cfs_rq->runnable_load_avg + 1); |
| } |
| #else |
| static inline void update_blocked_averages(int cpu) |
| { |
| } |
| |
| static unsigned long task_h_load(struct task_struct *p) |
| { |
| return p->se.avg.load_avg_contrib; |
| } |
| #endif |
| |
| /********** Helpers for find_busiest_group ************************/ |
| /* |
| * sg_lb_stats - stats of a sched_group required for load_balancing |
| */ |
| struct sg_lb_stats { |
| unsigned long avg_load; /*Avg load across the CPUs of the group */ |
| unsigned long group_load; /* Total load over the CPUs of the group */ |
| unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
| unsigned long load_per_task; |
| unsigned long group_power; |
| unsigned int sum_nr_running; /* Nr tasks running in the group */ |
| unsigned int group_capacity; |
| unsigned int idle_cpus; |
| unsigned int group_weight; |
| int group_imb; /* Is there an imbalance in the group ? */ |
| int group_has_capacity; /* Is there extra capacity in the group? */ |
| #ifdef CONFIG_NUMA_BALANCING |
| unsigned int nr_numa_running; |
| unsigned int nr_preferred_running; |
| #endif |
| }; |
| |
| /* |
| * sd_lb_stats - Structure to store the statistics of a sched_domain |
| * during load balancing. |
| */ |
| struct sd_lb_stats { |
| struct sched_group *busiest; /* Busiest group in this sd */ |
| struct sched_group *local; /* Local group in this sd */ |
| unsigned long total_load; /* Total load of all groups in sd */ |
| unsigned long total_pwr; /* Total power of all groups in sd */ |
| unsigned long avg_load; /* Average load across all groups in sd */ |
| |
| struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
| struct sg_lb_stats local_stat; /* Statistics of the local group */ |
| }; |
| |
| static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
| { |
| /* |
| * Skimp on the clearing to avoid duplicate work. We can avoid clearing |
| * local_stat because update_sg_lb_stats() does a full clear/assignment. |
| * We must however clear busiest_stat::avg_load because |
| * update_sd_pick_busiest() reads this before assignment. |
| */ |
| *sds = (struct sd_lb_stats){ |
| .busiest = NULL, |
| .local = NULL, |
| .total_load = 0UL, |
| .total_pwr = 0UL, |
| .busiest_stat = { |
| .avg_load = 0UL, |
| }, |
| }; |
| } |
| |
| /** |
| * get_sd_load_idx - Obtain the load index for a given sched domain. |
| * @sd: The sched_domain whose load_idx is to be obtained. |
| * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
| * |
| * Return: The load index. |
| */ |
| static inline int get_sd_load_idx(struct sched_domain *sd, |
| enum cpu_idle_type idle) |
| { |
| int load_idx; |
| |
| switch (idle) { |
| case CPU_NOT_IDLE: |
| load_idx = sd->busy_idx; |
| break; |
| |
| case CPU_NEWLY_IDLE: |
| load_idx = sd->newidle_idx; |
| break; |
| default: |
| load_idx = sd->idle_idx; |
| break; |
| } |
| |
| return load_idx; |
| } |
| |
| static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu) |
| { |
| return SCHED_POWER_SCALE; |
| } |
| |
| unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu) |
| { |
| return default_scale_freq_power(sd, cpu); |
| } |
| |
| static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu) |
| { |
| unsigned long weight = sd->span_weight; |
| unsigned long smt_gain = sd->smt_gain; |
| |
| smt_gain /= weight; |
| |
| return smt_gain; |
| } |
| |
| unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu) |
| { |
| return default_scale_smt_power(sd, cpu); |
| } |
| |
| static unsigned long scale_rt_power(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| u64 total, available, age_stamp, avg; |
| |
| /* |
| * Since we're reading these variables without serialization make sure |
| * we read them once before doing sanity checks on them. |
| */ |
| age_stamp = ACCESS_ONCE(rq->age_stamp); |
| avg = ACCESS_ONCE(rq->rt_avg); |
| |
| total = sched_avg_period() + (rq_clock(rq) - age_stamp); |
| |
| if (unlikely(total < avg)) { |
| /* Ensures that power won't end up being negative */ |
| available = 0; |
| } else { |
| available = total - avg; |
| } |
| |
| if (unlikely((s64)total < SCHED_POWER_SCALE)) |
| total = SCHED_POWER_SCALE; |
| |
| total >>= SCHED_POWER_SHIFT; |
| |
| return div_u64(available, total); |
| } |
| |
| static void update_cpu_power(struct sched_domain *sd, int cpu) |
| { |
| unsigned long weight = sd->span_weight; |
| unsigned long power = SCHED_POWER_SCALE; |
| struct sched_group *sdg = sd->groups; |
| |
| if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) { |
| if (sched_feat(ARCH_POWER)) |
| power *= arch_scale_smt_power(sd, cpu); |
| else |
| power *= default_scale_smt_power(sd, cpu); |
| |
| power >>= SCHED_POWER_SHIFT; |
| } |
| |
| sdg->sgp->power_orig = power; |
| |
| if (sched_feat(ARCH_POWER)) |
| power *= arch_scale_freq_power(sd, cpu); |
| else |
| power *= default_scale_freq_power(sd, cpu); |
| |
| power >>= SCHED_POWER_SHIFT; |
| |
| power *= scale_rt_power(cpu); |
| power >>= SCHED_POWER_SHIFT; |
| |
| if (!power) |
| power = 1; |
| |
| cpu_rq(cpu)->cpu_power = power; |
| sdg->sgp->power = power; |
| } |
| |
| void update_group_power(struct sched_domain *sd, int cpu) |
| { |
| struct sched_domain *child = sd->child; |
| struct sched_group *group, *sdg = sd->groups; |
| unsigned long power, power_orig; |
| unsigned long interval; |
| |
| interval = msecs_to_jiffies(sd->balance_interval); |
| interval = clamp(interval, 1UL, max_load_balance_interval); |
| sdg->sgp->next_update = jiffies + interval; |
| |
| if (!child) { |
| update_cpu_power(sd, cpu); |
| return; |
| } |
| |
| power_orig = power = 0; |
| |
| if (child->flags & SD_OVERLAP) { |
| /* |
| * SD_OVERLAP domains cannot assume that child groups |
| * span the current group. |
| */ |
| |
| for_each_cpu(cpu, sched_group_cpus(sdg)) { |
| struct sched_group_power *sgp; |
| struct rq *rq = cpu_rq(cpu); |
| |
| /* |
| * build_sched_domains() -> init_sched_groups_power() |
| * gets here before we've attached the domains to the |
| * runqueues. |
| * |
| * Use power_of(), which is set irrespective of domains |
| * in update_cpu_power(). |
| * |
| * This avoids power/power_orig from being 0 and |
| * causing divide-by-zero issues on boot. |
| * |
| * Runtime updates will correct power_orig. |
| */ |
| if (unlikely(!rq->sd)) { |
| power_orig += power_of(cpu); |
| power += power_of(cpu); |
| continue; |
| } |
| |
| sgp = rq->sd->groups->sgp; |
| power_orig += sgp->power_orig; |
| power += sgp->power; |
| } |
| } else { |
| /* |
| * !SD_OVERLAP domains can assume that child groups |
| * span the current group. |
| */ |
| |
| group = child->groups; |
| do { |
| power_orig += group->sgp->power_orig; |
| power += group->sgp->power; |
| group = group->next; |
| } while (group != child->groups); |
| } |
| |
| sdg->sgp->power_orig = power_orig; |
| sdg->sgp->power = power; |
| } |
| |
| /* |
| * Try and fix up capacity for tiny siblings, this is needed when |
| * things like SD_ASYM_PACKING need f_b_g to select another sibling |
| * which on its own isn't powerful enough. |
| * |
| * See update_sd_pick_busiest() and check_asym_packing(). |
| */ |
| static inline int |
| fix_small_capacity(struct sched_domain *sd, struct sched_group *group) |
| { |
| /* |
| * Only siblings can have significantly less than SCHED_POWER_SCALE |
| */ |
| if (!(sd->flags & SD_SHARE_CPUPOWER)) |
| return 0; |
| |
| /* |
| * If ~90% of the cpu_power is still there, we're good. |
| */ |
| if (group->sgp->power * 32 > group->sgp->power_orig * 29) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* |
| * Group imbalance indicates (and tries to solve) the problem where balancing |
| * groups is inadequate due to tsk_cpus_allowed() constraints. |
| * |
| * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a |
| * cpumask covering 1 cpu of the first group and 3 cpus of the second group. |
| * Something like: |
| * |
| * { 0 1 2 3 } { 4 5 6 7 } |
| * * * * * |
| * |
| * If we were to balance group-wise we'd place two tasks in the first group and |
| * two tasks in the second group. Clearly this is undesired as it will overload |
| * cpu 3 and leave one of the cpus in the second group unused. |
| * |
| * The current solution to this issue is detecting the skew in the first group |
| * by noticing the lower domain failed to reach balance and had difficulty |
| * moving tasks due to affinity constraints. |
| * |
| * When this is so detected; this group becomes a candidate for busiest; see |
| * update_sd_pick_busiest(). And calculate_imbalance() and |
| * find_busiest_group() avoid some of the usual balance conditions to allow it |
| * to create an effective group imbalance. |
| * |
| * This is a somewhat tricky proposition since the next run might not find the |
| * group imbalance and decide the groups need to be balanced again. A most |
| * subtle and fragile situation. |
| */ |
| |
| static inline int sg_imbalanced(struct sched_group *group) |
| { |
| return group->sgp->imbalance; |
| } |
| |
| /* |
| * Compute the group capacity. |
| * |
| * Avoid the issue where N*frac(smt_power) >= 1 creates 'phantom' cores by |
| * first dividing out the smt factor and computing the actual number of cores |
| * and limit power unit capacity with that. |
| */ |
| static inline int sg_capacity(struct lb_env *env, struct sched_group *group) |
| { |
| unsigned int capacity, smt, cpus; |
| unsigned int power, power_orig; |
| |
| power = group->sgp->power; |
| power_orig = group->sgp->power_orig; |
| cpus = group->group_weight; |
| |
| /* smt := ceil(cpus / power), assumes: 1 < smt_power < 2 */ |
| smt = DIV_ROUND_UP(SCHED_POWER_SCALE * cpus, power_orig); |
| capacity = cpus / smt; /* cores */ |
| |
| capacity = min_t(unsigned, capacity, DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE)); |
| if (!capacity) |
| capacity = fix_small_capacity(env->sd, group); |
| |
| return capacity; |
| } |
| |
| /** |
| * update_sg_lb_stats - Update sched_group's statistics for load balancing. |
| * @env: The load balancing environment. |
| * @group: sched_group whose statistics are to be updated. |
| * @load_idx: Load index of sched_domain of this_cpu for load calc. |
| * @local_group: Does group contain this_cpu. |
| * @sgs: variable to hold the statistics for this group. |
| */ |
| static inline void update_sg_lb_stats(struct lb_env *env, |
| struct sched_group *group, int load_idx, |
| int local_group, struct sg_lb_stats *sgs) |
| { |
| unsigned long load; |
| int i; |
| |
| memset(sgs, 0, sizeof(*sgs)); |
| |
| for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
| struct rq *rq = cpu_rq(i); |
| |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = target_load(i, load_idx); |
| else |
| load = source_load(i, load_idx); |
| |
| sgs->group_load += load; |
| sgs->sum_nr_running += rq->nr_running; |
| #ifdef CONFIG_NUMA_BALANCING |
| sgs->nr_numa_running += rq->nr_numa_running; |
| sgs->nr_preferred_running += rq->nr_preferred_running; |
| #endif |
| sgs->sum_weighted_load += weighted_cpuload(i); |
| if (idle_cpu(i)) |
| sgs->idle_cpus++; |
| } |
| |
| /* Adjust by relative CPU power of the group */ |
| sgs->group_power = group->sgp->power; |
| sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_power; |
| |
| if (sgs->sum_nr_running) |
| sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
| |
| sgs->group_weight = group->group_weight; |
| |
| sgs->group_imb = sg_imbalanced(group); |
| sgs->group_capacity = sg_capacity(env, group); |
| |
| if (sgs->group_capacity > sgs->sum_nr_running) |
| sgs->group_has_capacity = 1; |
| } |
| |
| /** |
| * update_sd_pick_busiest - return 1 on busiest group |
| * @env: The load balancing environment. |
| * @sds: sched_domain statistics |
| * @sg: sched_group candidate to be checked for being the busiest |
| * @sgs: sched_group statistics |
| * |
| * Determine if @sg is a busier group than the previously selected |
| * busiest group. |
| * |
| * Return: %true if @sg is a busier group than the previously selected |
| * busiest group. %false otherwise. |
| */ |
| static bool update_sd_pick_busiest(struct lb_env *env, |
| struct sd_lb_stats *sds, |
| struct sched_group *sg, |
| struct sg_lb_stats *sgs) |
| { |
| if (sgs->avg_load <= sds->busiest_stat.avg_load) |
| return false; |
| |
| if (sgs->sum_nr_running > sgs->group_capacity) |
| return true; |
| |
| if (sgs->group_imb) |
| return true; |
| |
| /* |
| * ASYM_PACKING needs to move all the work to the lowest |
| * numbered CPUs in the group, therefore mark all groups |
| * higher than ourself as busy. |
| */ |
| if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running && |
| env->dst_cpu < group_first_cpu(sg)) { |
| if (!sds->busiest) |
| return true; |
| |
| if (group_first_cpu(sds->busiest) > group_first_cpu(sg)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) |
| { |
| if (sgs->sum_nr_running > sgs->nr_numa_running) |
| return regular; |
| if (sgs->sum_nr_running > sgs->nr_preferred_running) |
| return remote; |
| return all; |
| } |
| |
| static inline enum fbq_type fbq_classify_rq(struct rq *rq) |
| { |
| if (rq->nr_running > rq->nr_numa_running) |
| return regular; |
| if (rq->nr_running > rq->nr_preferred_running) |
| return remote; |
| return all; |
| } |
| #else |
| static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) |
| { |
| return all; |
| } |
| |
| static inline enum fbq_type fbq_classify_rq(struct rq *rq) |
| { |
| return regular; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| /** |
| * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
| * @env: The load balancing environment. |
| * @sds: variable to hold the statistics for this sched_domain. |
| */ |
| static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| struct sched_domain *child = env->sd->child; |
| struct sched_group *sg = env->sd->groups; |
| struct sg_lb_stats tmp_sgs; |
| int load_idx, prefer_sibling = 0; |
| |
| if (child && child->flags & SD_PREFER_SIBLING) |
| prefer_sibling = 1; |
| |
| load_idx = get_sd_load_idx(env->sd, env->idle); |
| |
| do { |
| struct sg_lb_stats *sgs = &tmp_sgs; |
| int local_group; |
| |
| local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); |
| if (local_group) { |
| sds->local = sg; |
| sgs = &sds->local_stat; |
| |
| if (env->idle != CPU_NEWLY_IDLE || |
| time_after_eq(jiffies, sg->sgp->next_update)) |
| update_group_power(env->sd, env->dst_cpu); |
| } |
| |
| update_sg_lb_stats(env, sg, load_idx, local_group, sgs); |
| |
| if (local_group) |
| goto next_group; |
| |
| /* |
| * In case the child domain prefers tasks go to siblings |
| * first, lower the sg capacity to one so that we'll try |
| * and move all the excess tasks away. We lower the capacity |
| * of a group only if the local group has the capacity to fit |
| * these excess tasks, i.e. nr_running < group_capacity. The |
| * extra check prevents the case where you always pull from the |
| * heaviest group when it is already under-utilized (possible |
| * with a large weight task outweighs the tasks on the system). |
| */ |
| if (prefer_sibling && sds->local && |
| sds->local_stat.group_has_capacity) |
| sgs->group_capacity = min(sgs->group_capacity, 1U); |
| |
| if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
| sds->busiest = sg; |
| sds->busiest_stat = *sgs; |
| } |
| |
| next_group: |
| /* Now, start updating sd_lb_stats */ |
| sds->total_load += sgs->group_load; |
| sds->total_pwr += sgs->group_power; |
| |
| sg = sg->next; |
| } while (sg != env->sd->groups); |
| |
| if (env->sd->flags & SD_NUMA) |
| env->fbq_type = fbq_classify_group(&sds->busiest_stat); |
| } |
| |
| /** |
| * check_asym_packing - Check to see if the group is packed into the |
| * sched doman. |
| * |
| * This is primarily intended to used at the sibling level. Some |
| * cores like POWER7 prefer to use lower numbered SMT threads. In the |
| * case of POWER7, it can move to lower SMT modes only when higher |
| * threads are idle. When in lower SMT modes, the threads will |
| * perform better since they share less core resources. Hence when we |
| * have idle threads, we want them to be the higher ones. |
| * |
| * This packing function is run on idle threads. It checks to see if |
| * the busiest CPU in this domain (core in the P7 case) has a higher |
| * CPU number than the packing function is being run on. Here we are |
| * assuming lower CPU number will be equivalent to lower a SMT thread |
| * number. |
| * |
| * Return: 1 when packing is required and a task should be moved to |
| * this CPU. The amount of the imbalance is returned in *imbalance. |
| * |
| * @env: The load balancing environment. |
| * @sds: Statistics of the sched_domain which is to be packed |
| */ |
| static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| int busiest_cpu; |
| |
| if (!(env->sd->flags & SD_ASYM_PACKING)) |
| return 0; |
| |
| if (!sds->busiest) |
| return 0; |
| |
| busiest_cpu = group_first_cpu(sds->busiest); |
| if (env->dst_cpu > busiest_cpu) |
| return 0; |
| |
| env->imbalance = DIV_ROUND_CLOSEST( |
| sds->busiest_stat.avg_load * sds->busiest_stat.group_power, |
| SCHED_POWER_SCALE); |
| |
| return 1; |
| } |
| |
| /** |
| * fix_small_imbalance - Calculate the minor imbalance that exists |
| * amongst the groups of a sched_domain, during |
| * load balancing. |
| * @env: The load balancing environment. |
| * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
| */ |
| static inline |
| void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| unsigned long tmp, pwr_now = 0, pwr_move = 0; |
| unsigned int imbn = 2; |
| unsigned long scaled_busy_load_per_task; |
| struct sg_lb_stats *local, *busiest; |
| |
| local = &sds->local_stat; |
| busiest = &sds->busiest_stat; |
| |
| if (!local->sum_nr_running) |
| local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); |
| else if (busiest->load_per_task > local->load_per_task) |
| imbn = 1; |
| |
| scaled_busy_load_per_task = |
| (busiest->load_per_task * SCHED_POWER_SCALE) / |
| busiest->group_power; |
| |
| if (busiest->avg_load + scaled_busy_load_per_task >= |
| local->avg_load + (scaled_busy_load_per_task * imbn)) { |
| env->imbalance = busiest->load_per_task; |
| return; |
| } |
| |
| /* |
| * OK, we don't have enough imbalance to justify moving tasks, |
| * however we may be able to increase total CPU power used by |
| * moving them. |
| */ |
| |
| pwr_now += busiest->group_power * |
| min(busiest->load_per_task, busiest->avg_load); |
| pwr_now += local->group_power * |
| min(local->load_per_task, local->avg_load); |
| pwr_now /= SCHED_POWER_SCALE; |
| |
| /* Amount of load we'd subtract */ |
| tmp = (busiest->load_per_task * SCHED_POWER_SCALE) / |
| busiest->group_power; |
| if (busiest->avg_load > tmp) { |
| pwr_move += busiest->group_power * |
| min(busiest->load_per_task, |
| busiest->avg_load - tmp); |
| } |
| |
| /* Amount of load we'd add */ |
| if (busiest->avg_load * busiest->group_power < |
| busiest->load_per_task * SCHED_POWER_SCALE) { |
| tmp = (busiest->avg_load * busiest->group_power) / |
| local->group_power; |
| } else { |
| tmp = (busiest->load_per_task * SCHED_POWER_SCALE) / |
| local->group_power; |
| } |
| pwr_move += local->group_power * |
| min(local->load_per_task, local->avg_load + tmp); |
| pwr_move /= SCHED_POWER_SCALE; |
| |
| /* Move if we gain throughput */ |
| if (pwr_move > pwr_now) |
| env->imbalance = busiest->load_per_task; |
| } |
| |
| /** |
| * calculate_imbalance - Calculate the amount of imbalance present within the |
| * groups of a given sched_domain during load balance. |
| * @env: load balance environment |
| * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
| */ |
| static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| unsigned long max_pull, load_above_capacity = ~0UL; |
| struct sg_lb_stats *local, *busiest; |
| |
| local = &sds->local_stat; |
| busiest = &sds->busiest_stat; |
| |
| if (busiest->group_imb) { |
| /* |
| * In the group_imb case we cannot rely on group-wide averages |
| * to ensure cpu-load equilibrium, look at wider averages. XXX |
| */ |
| busiest->load_per_task = |
| min(busiest->load_per_task, sds->avg_load); |
| } |
| |
| /* |
| * In the presence of smp nice balancing, certain scenarios can have |
| * max load less than avg load(as we skip the groups at or below |
| * its cpu_power, while calculating max_load..) |
| */ |
| if (busiest->avg_load <= sds->avg_load || |
| local->avg_load >= sds->avg_load) { |
| env->imbalance = 0; |
| return fix_small_imbalance(env, sds); |
| } |
| |
| if (!busiest->group_imb) { |
| /* |
| * Don't want to pull so many tasks that a group would go idle. |
| * Except of course for the group_imb case, since then we might |
| * have to drop below capacity to reach cpu-load equilibrium. |
| */ |
| load_above_capacity = |
| (busiest->sum_nr_running - busiest->group_capacity); |
| |
| load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE); |
| load_above_capacity /= busiest->group_power; |
| } |
| |
| /* |
| * We're trying to get all the cpus to the average_load, so we don't |
| * want to push ourselves above the average load, nor do we wish to |
| * reduce the max loaded cpu below the average load. At the same time, |
| * we also don't want to reduce the group load below the group capacity |
| * (so that we can implement power-savings policies etc). Thus we look |
| * for the minimum possible imbalance. |
| */ |
| max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
| |
| /* How much load to actually move to equalise the imbalance */ |
| env->imbalance = min( |
| max_pull * busiest->group_power, |
| (sds->avg_load - local->avg_load) * local->group_power |
| ) / SCHED_POWER_SCALE; |
| |
| /* |
| * if *imbalance is less than the average load per runnable task |
| * there is no guarantee that any tasks will be moved so we'll have |
| * a think about bumping its value to force at least one task to be |
| * moved |
| */ |
| if (env->imbalance < busiest->load_per_task) |
| return fix_small_imbalance(env, sds); |
| } |
| |
| /******* find_busiest_group() helpers end here *********************/ |
| |
| /** |
| * find_busiest_group - Returns the busiest group within the sched_domain |
| * if there is an imbalance. If there isn't an imbalance, and |
| * the user has opted for power-savings, it returns a group whose |
| * CPUs can be put to idle by rebalancing those tasks elsewhere, if |
| * such a group exists. |
| * |
| * Also calculates the amount of weighted load which should be moved |
| * to restore balance. |
| * |
| * @env: The load balancing environment. |
| * |
| * Return: - The busiest group if imbalance exists. |
| * - If no imbalance and user has opted for power-savings balance, |
| * return the least loaded group whose CPUs can be |
| * put to idle by rebalancing its tasks onto our group. |
| */ |
| static struct sched_group *find_busiest_group(struct lb_env *env) |
| { |
| struct sg_lb_stats *local, *busiest; |
| struct sd_lb_stats sds; |
| |
| init_sd_lb_stats(&sds); |
| |
| /* |
| * Compute the various statistics relavent for load balancing at |
| * this level. |
| */ |
| update_sd_lb_stats(env, &sds); |
| local = &sds.local_stat; |
| busiest = &sds.busiest_stat; |
| |
| if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) && |
| check_asym_packing(env, &sds)) |
| return sds.busiest; |
| |
| /* There is no busy sibling group to pull tasks from */ |
| if (!sds.busiest || busiest->sum_nr_running == 0) |
| goto out_balanced; |
| |
| sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr; |
| |
| /* |
| * If the busiest group is imbalanced the below checks don't |
| * work because they assume all things are equal, which typically |
| * isn't true due to cpus_allowed constraints and the like. |
| */ |
| if (busiest->group_imb) |
| goto force_balance; |
| |
| /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ |
| if (env->idle == CPU_NEWLY_IDLE && local->group_has_capacity && |
| !busiest->group_has_capacity) |
| goto force_balance; |
| |
| /* |
| * If the local group is more busy than the selected busiest group |
| * don't try and pull any tasks. |
| */ |
| if (local->avg_load >= busiest->avg_load) |
| goto out_balanced; |
| |
| /* |
| * Don't pull any tasks if this group is already above the domain |
| * average load. |
| */ |
| if (local->avg_load >= sds.avg_load) |
| goto out_balanced; |
| |
| if (env->idle == CPU_IDLE) { |
| /* |
| * This cpu is idle. If the busiest group load doesn't |
| * have more tasks than the number of available cpu's and |
| * there is no imbalance between this and busiest group |
| * wrt to idle cpu's, it is balanced. |
| */ |
| if ((local->idle_cpus < busiest->idle_cpus) && |
| busiest->sum_nr_running <= busiest->group_weight) |
| goto out_balanced; |
| } else { |
| /* |
| * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use |
| * imbalance_pct to be conservative. |
| */ |
| if (100 * busiest->avg_load <= |
| env->sd->imbalance_pct * local->avg_load) |
| goto out_balanced; |
| } |
| |
| force_balance: |
| /* Looks like there is an imbalance. Compute it */ |
| calculate_imbalance(env, &sds); |
| return sds.busiest; |
| |
| out_balanced: |
| env->imbalance = 0; |
| return NULL; |
| } |
| |
| /* |
| * find_busiest_queue - find the busiest runqueue among the cpus in group. |
| */ |
| static struct rq *find_busiest_queue(struct lb_env *env, |
| struct sched_group *group) |
| { |
| struct rq *busiest = NULL, *rq; |
| unsigned long busiest_load = 0, busiest_power = 1; |
| int i; |
| |
| for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
| unsigned long power, capacity, wl; |
| enum fbq_type rt; |
| |
| rq = cpu_rq(i); |
| rt = fbq_classify_rq(rq); |
| |
| /* |
| * We classify groups/runqueues into three groups: |
| * - regular: there are !numa tasks |
| * - remote: there are numa tasks that run on the 'wrong' node |
| * - all: there is no distinction |
| * |
| * In order to avoid migrating ideally placed numa tasks, |
| * ignore those when there's better options. |
| * |
| * If we ignore the actual busiest queue to migrate another |
| * task, the next balance pass can still reduce the busiest |
| * queue by moving tasks around inside the node. |
| * |
| * If we cannot move enough load due to this classification |
| * the next pass will adjust the group classification and |
| * allow migration of more tasks. |
| * |
| * Both cases only affect the total convergence complexity. |
| */ |
| if (rt > env->fbq_type) |
| continue; |
| |
| power = power_of(i); |
| capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE); |
| if (!capacity) |
| capacity = fix_small_capacity(env->sd, group); |
| |
| wl = weighted_cpuload(i); |
| |
| /* |
| * When comparing with imbalance, use weighted_cpuload() |
| * which is not scaled with the cpu power. |
| */ |
| if (capacity && rq->nr_running == 1 && wl > env->imbalance) |
| continue; |
| |
| /* |
| * For the load comparisons with the other cpu's, consider |
| * the weighted_cpuload() scaled with the cpu power, so that |
| * the load can be moved away from the cpu that is potentially |
| * running at a lower capacity. |
| * |
| * Thus we're looking for max(wl_i / power_i), crosswise |
| * multiplication to rid ourselves of the division works out |
| * to: wl_i * power_j > wl_j * power_i; where j is our |
| * previous maximum. |
| */ |
| if (wl * busiest_power > busiest_load * power) { |
| busiest_load = wl; |
| busiest_power = power; |
| busiest = rq; |
| } |
| } |
| |
| return busiest; |
| } |
| |
| /* |
| * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but |
| * so long as it is large enough. |
| */ |
| #define MAX_PINNED_INTERVAL 512 |
| |
| /* Working cpumask for load_balance and load_balance_newidle. */ |
| DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); |
| |
| static int need_active_balance(struct lb_env *env) |
| { |
| struct sched_domain *sd = env->sd; |
| |
| if (env->idle == CPU_NEWLY_IDLE) { |
| |
| /* |
| * ASYM_PACKING needs to force migrate tasks from busy but |
| * higher numbered CPUs in order to pack all tasks in the |
| * lowest numbered CPUs. |
| */ |
| if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) |
| return 1; |
| } |
| |
| return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); |
| } |
| |
| static int active_load_balance_cpu_stop(void *data); |
| |
| static int should_we_balance(struct lb_env *env) |
| { |
| struct sched_group *sg = env->sd->groups; |
| struct cpumask *sg_cpus, *sg_mask; |
| int cpu, balance_cpu = -1; |
| |
| /* |
| * In the newly idle case, we will allow all the cpu's |
| * to do the newly idle load balance. |
| */ |
| if (env->idle == CPU_NEWLY_IDLE) |
| return 1; |
| |
| sg_cpus = sched_group_cpus(sg); |
| sg_mask = sched_group_mask(sg); |
| /* Try to find first idle cpu */ |
| for_each_cpu_and(cpu, sg_cpus, env->cpus) { |
| if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) |
| continue; |
| |
| balance_cpu = cpu; |
| break; |
| } |
| |
| if (balance_cpu == -1) |
| balance_cpu = group_balance_cpu(sg); |
| |
| /* |
| * First idle cpu or the first cpu(busiest) in this sched group |
| * is eligible for doing load balancing at this and above domains. |
| */ |
| return balance_cpu == env->dst_cpu; |
| } |
| |
| /* |
| * Check this_cpu to ensure it is balanced within domain. Attempt to move |
| * tasks if there is an imbalance. |
| */ |
| static int load_balance(int this_cpu, struct rq *this_rq, |
| struct sched_domain *sd, enum cpu_idle_type idle, |
| int *continue_balancing) |
| { |
| int ld_moved, cur_ld_moved, active_balance = 0; |
| struct sched_domain *sd_parent = sd->parent; |
| struct sched_group *group; |
| struct rq *busiest; |
| unsigned long flags; |
| struct cpumask *cpus = __get_cpu_var(load_balance_mask); |
| |
| struct lb_env env = { |
| .sd = sd, |
| .dst_cpu = this_cpu, |
| .dst_rq = this_rq, |
| .dst_grpmask = sched_group_cpus(sd->groups), |
| .idle = idle, |
| .loop_break = sched_nr_migrate_break, |
| .cpus = cpus, |
| .fbq_type = all, |
| }; |
| |
| /* |
| * For NEWLY_IDLE load_balancing, we don't need to consider |
| * other cpus in our group |
| */ |
| if (idle == CPU_NEWLY_IDLE) |
| env.dst_grpmask = NULL; |
| |
| cpumask_copy(cpus, cpu_active_mask); |
| |
| schedstat_inc(sd, lb_count[idle]); |
| |
| redo: |
| if (!should_we_balance(&env)) { |
| *continue_balancing = 0; |
| goto out_balanced; |
| } |
| |
| group = find_busiest_group(&env); |
| if (!group) { |
| schedstat_inc(sd, lb_nobusyg[idle]); |
| goto out_balanced; |
| } |
| |
| busiest = find_busiest_queue(&env, group); |
| if (!busiest) { |
| schedstat_inc(sd, lb_nobusyq[idle]); |
| goto out_balanced; |
| } |
| |
| BUG_ON(busiest == env.dst_rq); |
| |
| schedstat_add(sd, lb_imbalance[idle], env.imbalance); |
| |
| ld_moved = 0; |
| if (busiest->nr_running > 1) { |
| /* |
| * Attempt to move tasks. If find_busiest_group has found |
| * an imbalance but busiest->nr_running <= 1, the group is |
| * still unbalanced. ld_moved simply stays zero, so it is |
| * correctly treated as an imbalance. |
| */ |
| env.flags |= LBF_ALL_PINNED; |
| env.src_cpu = busiest->cpu; |
| env.src_rq = busiest; |
| env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); |
| |
| more_balance: |
| local_irq_save(flags); |
| double_rq_lock(env.dst_rq, busiest); |
| |
| /* |
| * cur_ld_moved - load moved in current iteration |
| * ld_moved - cumulative load moved across iterations |
| */ |
| cur_ld_moved = move_tasks(&env); |
| ld_moved += cur_ld_moved; |
| double_rq_unlock(env.dst_rq, busiest); |
| local_irq_restore(flags); |
| |
| /* |
| * some other cpu did the load balance for us. |
| */ |
| if (cur_ld_moved && env.dst_cpu != smp_processor_id()) |
| resched_cpu(env.dst_cpu); |
| |
| if (env.flags & LBF_NEED_BREAK) { |
| env.flags &= ~LBF_NEED_BREAK; |
| goto more_balance; |
| } |
| |
| /* |
| * Revisit (affine) tasks on src_cpu that couldn't be moved to |
| * us and move them to an alternate dst_cpu in our sched_group |
| * where they can run. The upper limit on how many times we |
| * iterate on same src_cpu is dependent on number of cpus in our |
| * sched_group. |
| * |
| * This changes load balance semantics a bit on who can move |
| * load to a given_cpu. In addition to the given_cpu itself |
| * (or a ilb_cpu acting on its behalf where given_cpu is |
| * nohz-idle), we now have balance_cpu in a position to move |
| * load to given_cpu. In rare situations, this may cause |
| * conflicts (balance_cpu and given_cpu/ilb_cpu deciding |
| * _independently_ and at _same_ time to move some load to |
| * given_cpu) causing exceess load to be moved to given_cpu. |
| * This however should not happen so much in practice and |
| * moreover subsequent load balance cycles should correct the |
| * excess load moved. |
| */ |
| if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
| |
| /* Prevent to re-select dst_cpu via env's cpus */ |
| cpumask_clear_cpu(env.dst_cpu, env.cpus); |
| |
| env.dst_rq = cpu_rq(env.new_dst_cpu); |
| env.dst_cpu = env.new_dst_cpu; |
| env.flags &= ~LBF_DST_PINNED; |
| env.loop = 0; |
| env.loop_break = sched_nr_migrate_break; |
| |
| /* |
| * Go back to "more_balance" rather than "redo" since we |
| * need to continue with same src_cpu. |
| */ |
| goto more_balance; |
| } |
| |
| /* |
| * We failed to reach balance because of affinity. |
| */ |
| if (sd_parent) { |
| int *group_imbalance = &sd_parent->groups->sgp->imbalance; |
| |
| if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) { |
| *group_imbalance = 1; |
| } else if (*group_imbalance) |
| *group_imbalance = 0; |
| } |
| |
| /* All tasks on this runqueue were pinned by CPU affinity */ |
| if (unlikely(env.flags & LBF_ALL_PINNED)) { |
| cpumask_clear_cpu(cpu_of(busiest), cpus); |
| if (!cpumask_empty(cpus)) { |
| env.loop = 0; |
| env.loop_break = sched_nr_migrate_break; |
| goto redo; |
| } |
| goto out_balanced; |
| } |
| } |
| |
| if (!ld_moved) { |
| schedstat_inc(sd, lb_failed[idle]); |
| /* |
| * Increment the failure counter only on periodic balance. |
| * We do not want newidle balance, which can be very |
| * frequent, pollute the failure counter causing |
| * excessive cache_hot migrations and active balances. |
| */ |
| if (idle != CPU_NEWLY_IDLE) |
| sd->nr_balance_failed++; |
| |
| if (need_active_balance(&env)) { |
| raw_spin_lock_irqsave(&busiest->lock, flags); |
| |
| /* don't kick the active_load_balance_cpu_stop, |
| * if the curr task on busiest cpu can't be |
| * moved to this_cpu |
| */ |
| if (!cpumask_test_cpu(this_cpu, |
| tsk_cpus_allowed(busiest->curr))) { |
| raw_spin_unlock_irqrestore(&busiest->lock, |
| flags); |
| env.flags |= LBF_ALL_PINNED; |
| goto out_one_pinned; |
| } |
| |
| /* |
| * ->active_balance synchronizes accesses to |
| * ->active_balance_work. Once set, it's cleared |
| * only after active load balance is finished. |
| */ |
| if (!busiest->active_balance) { |
| busiest->active_balance = 1; |
| busiest->push_cpu = this_cpu; |
| active_balance = 1; |
| } |
| raw_spin_unlock_irqrestore(&busiest->lock, flags); |
| |
| if (active_balance) { |
| stop_one_cpu_nowait(cpu_of(busiest), |
| active_load_balance_cpu_stop, busiest, |
| &busiest->active_balance_work); |
| } |
| |
| /* |
| * We've kicked active balancing, reset the failure |
| * counter. |
| */ |
| sd->nr_balance_failed = sd->cache_nice_tries+1; |
| } |
| } else |
| sd->nr_balance_failed = 0; |
| |
| if (likely(!active_balance)) { |
| /* We were unbalanced, so reset the balancing interval */ |
| sd->balance_interval = sd->min_interval; |
| } else { |
| /* |
| * If we've begun active balancing, start to back off. This |
| * case may not be covered by the all_pinned logic if there |
| * is only 1 task on the busy runqueue (because we don't call |
| * move_tasks). |
| */ |
| if (sd->balance_interval < sd->max_interval) |
| sd->balance_interval *= 2; |
| } |
| |
| goto out; |
| |
| out_balanced: |
| schedstat_inc(sd, lb_balanced[idle]); |
| |
| sd->nr_balance_failed = 0; |
| |
| out_one_pinned: |
| /* tune up the balancing interval */ |
| if (((env.flags & LBF_ALL_PINNED) && |
| sd->balance_interval < MAX_PINNED_INTERVAL) || |
| (sd->balance_interval < sd->max_interval)) |
| sd->balance_interval *= 2; |
| |
| ld_moved = 0; |
| out: |
| return ld_moved; |
| } |
| |
| /* |
| * idle_balance is called by schedule() if this_cpu is about to become |
| * idle. Attempts to pull tasks from other CPUs. |
| */ |
| void idle_balance(int this_cpu, struct rq *this_rq) |
| { |
| struct sched_domain *sd; |
| int pulled_task = 0; |
| unsigned long next_balance = jiffies + HZ; |
| u64 curr_cost = 0; |
| |
| this_rq->idle_stamp = rq_clock(this_rq); |
| |
| if (this_rq->avg_idle < sysctl_sched_migration_cost) |
| return; |
| |
| /* |
| * Drop the rq->lock, but keep IRQ/preempt disabled. |
| */ |
| raw_spin_unlock(&this_rq->lock); |
| |
| update_blocked_averages(this_cpu); |
| rcu_read_lock(); |
| for_each_domain(this_cpu, sd) { |
| unsigned long interval; |
| int continue_balancing = 1; |
| u64 t0, domain_cost; |
| |
| if (!(sd->flags & SD_LOAD_BALANCE)) |
| continue; |
| |
| if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) |
| break; |
| |
| if (sd->flags & SD_BALANCE_NEWIDLE) { |
| t0 = sched_clock_cpu(this_cpu); |
| |
| /* If we've pulled tasks over stop searching: */ |
| pulled_task = load_balance(this_cpu, this_rq, |
| sd, CPU_NEWLY_IDLE, |
| &continue_balancing); |
| |
| domain_cost = sched_clock_cpu(this_cpu) - t0; |
| if (domain_cost > sd->max_newidle_lb_cost) |
| sd->max_newidle_lb_cost = domain_cost; |
| |
| curr_cost += domain_cost; |
| } |
| |
| interval = msecs_to_jiffies(sd->balance_interval); |
| if (time_after(next_balance, sd->last_balance + interval)) |
| next_balance = sd->last_balance + interval; |
| if (pulled_task) { |
| this_rq->idle_stamp = 0; |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| |
| raw_spin_lock(&this_rq->lock); |
| |
| if (pulled_task || time_after(jiffies, this_rq->next_balance)) { |
| /* |
| * We are going idle. next_balance may be set based on |
| * a busy processor. So reset next_balance. |
| */ |
| this_rq->next_balance = next_balance; |
| } |
| |
| if (curr_cost > this_rq->max_idle_balance_cost) |
| this_rq->max_idle_balance_cost = curr_cost; |
| } |
| |
| /* |
| * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
| * running tasks off the busiest CPU onto idle CPUs. It requires at |
| * least 1 task to be running on each physical CPU where possible, and |
| * avoids physical / logical imbalances. |
| */ |
| static int active_load_balance_cpu_stop(void *data) |
| { |
| struct rq *busiest_rq = data; |
| int busiest_cpu = cpu_of(busiest_rq); |
| int target_cpu = busiest_rq->push_cpu; |
| struct rq *target_rq = cpu_rq(target_cpu); |
| struct sched_domain *sd; |
| |
| raw_spin_lock_irq(&busiest_rq->lock); |
| |
| /* make sure the requested cpu hasn't gone down in the meantime */ |
| if (unlikely(busiest_cpu != smp_processor_id() || |
| !busiest_rq->active_balance)) |
| goto out_unlock; |
| |
| /* Is there any task to move? */ |
| if (busiest_rq->nr_running <= 1) |
| goto out_unlock; |
| |
| /* |
| * This condition is "impossible", if it occurs |
| * we need to fix it. Originally reported by |
| * Bjorn Helgaas on a 128-cpu setup. |
| */ |
| BUG_ON(busiest_rq == target_rq); |
| |
| /* move a task from busiest_rq to target_rq */ |
| double_lock_balance(busiest_rq, target_rq); |
| |
| /* Search for an sd spanning us and the target CPU. */ |
| rcu_read_lock(); |
| for_each_domain(target_cpu, sd) { |
| if ((sd->flags & SD_LOAD_BALANCE) && |
| cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) |
| break; |
| } |
| |
| if (likely(sd)) { |
| struct lb_env env = { |
| .sd = sd, |
| .dst_cpu = target_cpu, |
| .dst_rq = target_rq, |
| .src_cpu = busiest_rq->cpu, |
| .src_rq = busiest_rq, |
| .idle = CPU_IDLE, |
| }; |
| |
| schedstat_inc(sd, alb_count); |
| |
| if (move_one_task(&env)) |
| schedstat_inc(sd, alb_pushed); |
| else |
| schedstat_inc(sd, alb_failed); |
| } |
| rcu_read_unlock(); |
| double_unlock_balance(busiest_rq, target_rq); |
| out_unlock: |
| busiest_rq->active_balance = 0; |
| raw_spin_unlock_irq(&busiest_rq->lock); |
| return 0; |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * idle load balancing details |
| * - When one of the busy CPUs notice that there may be an idle rebalancing |
| * needed, they will kick the idle load balancer, which then does idle |
| * load balancing for all the idle CPUs. |
| */ |
| static struct { |
| cpumask_var_t idle_cpus_mask; |
| atomic_t nr_cpus; |
| unsigned long next_balance; /* in jiffy units */ |
| } nohz ____cacheline_aligned; |
| |
| static inline int find_new_ilb(int call_cpu) |
| { |
| int ilb = cpumask_first(nohz.idle_cpus_mask); |
| |
| if (ilb < nr_cpu_ids && idle_cpu(ilb)) |
| return ilb; |
| |
| return nr_cpu_ids; |
| } |
| |
| /* |
| * Kick a CPU to do the nohz balancing, if it is time for it. We pick the |
| * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle |
| * CPU (if there is one). |
| */ |
| static void nohz_balancer_kick(int cpu) |
| { |
| int ilb_cpu; |
| |
| nohz.next_balance++; |
| |
| ilb_cpu = find_new_ilb(cpu); |
| |
| if (ilb_cpu >= nr_cpu_ids) |
| return; |
| |
| if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
| return; |
| /* |
| * Use smp_send_reschedule() instead of resched_cpu(). |
| * This way we generate a sched IPI on the target cpu which |
| * is idle. And the softirq performing nohz idle load balance |
| * will be run before returning from the IPI. |
| */ |
| smp_send_reschedule(ilb_cpu); |
| return; |
| } |
| |
| static inline void nohz_balance_exit_idle(int cpu) |
| { |
| if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { |
| cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); |
| atomic_dec(&nohz.nr_cpus); |
| clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
| } |
| } |
| |
| static inline void set_cpu_sd_state_busy(void) |
| { |
| struct sched_domain *sd; |
| int cpu = smp_processor_id(); |
| |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
| |
| if (!sd || !sd->nohz_idle) |
| goto unlock; |
| sd->nohz_idle = 0; |
| |
| atomic_inc(&sd->groups->sgp->nr_busy_cpus); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| void set_cpu_sd_state_idle(void) |
| { |
| struct sched_domain *sd; |
| int cpu = smp_processor_id(); |
| |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
| |
| if (!sd || sd->nohz_idle) |
| goto unlock; |
| sd->nohz_idle = 1; |
| |
| atomic_dec(&sd->groups->sgp->nr_busy_cpus); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * This routine will record that the cpu is going idle with tick stopped. |
| * This info will be used in performing idle load balancing in the future. |
| */ |
| void nohz_balance_enter_idle(int cpu) |
| { |
| /* |
| * If this cpu is going down, then nothing needs to be done. |
| */ |
| if (!cpu_active(cpu)) |
| return; |
| |
| if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
| return; |
| |
| cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
| atomic_inc(&nohz.nr_cpus); |
| set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
| } |
| |
| static int sched_ilb_notifier(struct notifier_block *nfb, |
| unsigned long action, void *hcpu) |
| { |
| switch (action & ~CPU_TASKS_FROZEN) { |
| case CPU_DYING: |
| nohz_balance_exit_idle(smp_processor_id()); |
| return NOTIFY_OK; |
| default: |
| return NOTIFY_DONE; |
| } |
| } |
| #endif |
| |
| static DEFINE_SPINLOCK(balancing); |
| |
| /* |
| * Scale the max load_balance interval with the number of CPUs in the system. |
| * This trades load-balance latency on larger machines for less cross talk. |
| */ |
| void update_max_interval(void) |
| { |
| max_load_balance_interval = HZ*num_online_cpus()/10; |
| } |
| |
| /* |
| * It checks each scheduling domain to see if it is due to be balanced, |
| * and initiates a balancing operation if so. |
| * |
| * Balancing parameters are set up in init_sched_domains. |
| */ |
| static void rebalance_domains(int cpu, enum cpu_idle_type idle) |
| { |
| int continue_balancing = 1; |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long interval; |
| struct sched_domain *sd; |
| /* Earliest time when we have to do rebalance again */ |
| unsigned long next_balance = jiffies + 60*HZ; |
| int update_next_balance = 0; |
| int need_serialize, need_decay = 0; |
| u64 max_cost = 0; |
| |
| update_blocked_averages(cpu); |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, sd) { |
| /* |
| * Decay the newidle max times here because this is a regular |
| * visit to all the domains. Decay ~1% per second. |
| */ |
| if (time_after(jiffies, sd->next_decay_max_lb_cost)) { |
| sd->max_newidle_lb_cost = |
| (sd->max_newidle_lb_cost * 253) / 256; |
| sd->next_decay_max_lb_cost = jiffies + HZ; |
| need_decay = 1; |
| } |
| max_cost += sd->max_newidle_lb_cost; |
| |
| if (!(sd->flags & SD_LOAD_BALANCE)) |
| continue; |
| |
| /* |
| * Stop the load balance at this level. There is another |
| * CPU in our sched group which is doing load balancing more |
| * actively. |
| */ |
| if (!continue_balancing) { |
| if (need_decay) |
| continue; |
| break; |
| } |
| |
| interval = sd->balance_interval; |
| if (idle != CPU_IDLE) |
| interval *= sd->busy_factor; |
| |
| /* scale ms to jiffies */ |
| interval = msecs_to_jiffies(interval); |
| interval = clamp(interval, 1UL, max_load_balance_interval); |
| |
| need_serialize = sd->flags & SD_SERIALIZE; |
| |
| if (need_serialize) { |
| if (!spin_trylock(&balancing)) |
| goto out; |
| } |
| |
| if (time_after_eq(jiffies, sd->last_balance + interval)) { |
| if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
| /* |
| * The LBF_DST_PINNED logic could have changed |
| * env->dst_cpu, so we can't know our idle |
| * state even if we migrated tasks. Update it. |
| */ |
| idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
| } |
| sd->last_balance = jiffies; |
| } |
| if (need_serialize) |
| spin_unlock(&balancing); |
| out: |
| if (time_after(next_balance, sd->last_balance + interval)) { |
| next_balance = sd->last_balance + interval; |
| update_next_balance = 1; |
| } |
| } |
| if (need_decay) { |
| /* |
| * Ensure the rq-wide value also decays but keep it at a |
| * reasonable floor to avoid funnies with rq->avg_idle. |
| */ |
| rq->max_idle_balance_cost = |
| max((u64)sysctl_sched_migration_cost, max_cost); |
| } |
| rcu_read_unlock(); |
| |
| /* |
| * next_balance will be updated only when there is a need. |
| * When the cpu is attached to null domain for ex, it will not be |
| * updated. |
| */ |
| if (likely(update_next_balance)) |
| rq->next_balance = next_balance; |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
| * rebalancing for all the cpus for whom scheduler ticks are stopped. |
| */ |
| static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) |
| { |
| struct rq *this_rq = cpu_rq(this_cpu); |
| struct rq *rq; |
| int balance_cpu; |
| |
| if (idle != CPU_IDLE || |
| !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) |
| goto end; |
| |
| for_each_cpu(balance_cpu, nohz.idle_cpus_mask) { |
| if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
| continue; |
| |
| /* |
| * If this cpu gets work to do, stop the load balancing |
| * work being done for other cpus. Next load |
| * balancing owner will pick it up. |
| */ |
| if (need_resched()) |
| break; |
| |
| rq = cpu_rq(balance_cpu); |
| |
| raw_spin_lock_irq(&rq->lock); |
| update_rq_clock(rq); |
| update_idle_cpu_load(rq); |
| raw_spin_unlock_irq(&rq->lock); |
| |
| rebalance_domains(balance_cpu, CPU_IDLE); |
| |
| if (time_after(this_rq->next_balance, rq->next_balance)) |
| this_rq->next_balance = rq->next_balance; |
| } |
| nohz.next_balance = this_rq->next_balance; |
| end: |
| clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); |
| } |
| |
| /* |
| * Current heuristic for kicking the idle load balancer in the presence |
| * of an idle cpu is the system. |
| * - This rq has more than one task. |
| * - At any scheduler domain level, this cpu's scheduler group has multiple |
| * busy cpu's exceeding the group's power. |
| * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
| * domain span are idle. |
| */ |
| static inline int nohz_kick_needed(struct rq *rq, int cpu) |
| { |
| unsigned long now = jiffies; |
| struct sched_domain *sd; |
| struct sched_group_power *sgp; |
| int nr_busy; |
| |
| if (unlikely(idle_cpu(cpu))) |
| return 0; |
| |
| /* |
| * We may be recently in ticked or tickless idle mode. At the first |
| * busy tick after returning from idle, we will update the busy stats. |
| */ |
| set_cpu_sd_state_busy(); |
| nohz_balance_exit_idle(cpu); |
| |
| /* |
| * None are in tickless mode and hence no need for NOHZ idle load |
| * balancing. |
| */ |
| if (likely(!atomic_read(&nohz.nr_cpus))) |
| return 0; |
| |
| if (time_before(now, nohz.next_balance)) |
| return 0; |
| |
| if (rq->nr_running >= 2) |
| goto need_kick; |
| |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_busy, cpu)); |
| |
| if (sd) { |
| sgp = sd->groups->sgp; |
| nr_busy = atomic_read(&sgp->nr_busy_cpus); |
| |
| if (nr_busy > 1) |
| goto need_kick_unlock; |
| } |
| |
| sd = rcu_dereference(per_cpu(sd_asym, cpu)); |
| |
| if (sd && (cpumask_first_and(nohz.idle_cpus_mask, |
| sched_domain_span(sd)) < cpu)) |
| goto need_kick_unlock; |
| |
| rcu_read_unlock(); |
| return 0; |
| |
| need_kick_unlock: |
| rcu_read_unlock(); |
| need_kick: |
| return 1; |
| } |
| #else |
| static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { } |
| #endif |
| |
| /* |
| * run_rebalance_domains is triggered when needed from the scheduler tick. |
| * Also triggered for nohz idle balancing (with nohz_balancing_kick set). |
| */ |
| static void run_rebalance_domains(struct softirq_action *h) |
| { |
| int this_cpu = smp_processor_id(); |
| struct rq *this_rq = cpu_rq(this_cpu); |
| enum cpu_idle_type idle = this_rq->idle_balance ? |
| CPU_IDLE : CPU_NOT_IDLE; |
| |
| rebalance_domains(this_cpu, idle); |
| |
| /* |
| * If this cpu has a pending nohz_balance_kick, then do the |
| * balancing on behalf of the other idle cpus whose ticks are |
| * stopped. |
| */ |
| nohz_idle_balance(this_cpu, idle); |
| } |
| |
| static inline int on_null_domain(int cpu) |
| { |
| return !rcu_dereference_sched(cpu_rq(cpu)->sd); |
| } |
| |
| /* |
| * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. |
| */ |
| void trigger_load_balance(struct rq *rq, int cpu) |
| { |
| /* Don't need to rebalance while attached to NULL domain */ |
| if (time_after_eq(jiffies, rq->next_balance) && |
| likely(!on_null_domain(cpu))) |
| raise_softirq(SCHED_SOFTIRQ); |
| #ifdef CONFIG_NO_HZ_COMMON |
| if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu))) |
| nohz_balancer_kick(cpu); |
| #endif |
| } |
| |
| static void rq_online_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| } |
| |
| static void rq_offline_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| |
| /* Ensure any throttled groups are reachable by pick_next_task */ |
| unthrottle_offline_cfs_rqs(rq); |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * scheduler tick hitting a task of our scheduling class: |
| */ |
| static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &curr->se; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| entity_tick(cfs_rq, se, queued); |
| } |
| |
| if (numabalancing_enabled) |
| task_tick_numa(rq, curr); |
| |
| update_rq_runnable_avg(rq, 1); |
| } |
| |
| /* |
| * called on fork with the child task as argument from the parent's context |
| * - child not yet on the tasklist |
| * - preemption disabled |
| */ |
| static void task_fork_fair(struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se, *curr; |
| int this_cpu = smp_processor_id(); |
| struct rq *rq = this_rq(); |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| |
| update_rq_clock(rq); |
| |
| cfs_rq = task_cfs_rq(current); |
| curr = cfs_rq->curr; |
| |
| /* |
| * Not only the cpu but also the task_group of the parent might have |
| * been changed after parent->se.parent,cfs_rq were copied to |
| * child->se.parent,cfs_rq. So call __set_task_cpu() to make those |
| * of child point to valid ones. |
| */ |
| rcu_read_lock(); |
| __set_task_cpu(p, this_cpu); |
| rcu_read_unlock(); |
| |
| update_curr(cfs_rq); |
| |
| if (curr) |
| se->vruntime = curr->vruntime; |
| place_entity(cfs_rq, se, 1); |
| |
| if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
| /* |
| * Upon rescheduling, sched_class::put_prev_task() will place |
| * 'current' within the tree based on its new key value. |
| */ |
| swap(curr->vruntime, se->vruntime); |
| resched_task(rq->curr); |
| } |
| |
| se->vruntime -= cfs_rq->min_vruntime; |
| |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| /* |
| * Priority of the task has changed. Check to see if we preempt |
| * the current task. |
| */ |
| static void |
| prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) |
| { |
| if (!p->se.on_rq) |
| return; |
| |
| /* |
| * Reschedule if we are currently running on this runqueue and |
| * our priority decreased, or if we are not currently running on |
| * this runqueue and our priority is higher than the current's |
| */ |
| if (rq->curr == p) { |
| if (p->prio > oldprio) |
| resched_task(rq->curr); |
| } else |
| check_preempt_curr(rq, p, 0); |
| } |
| |
| static void switched_from_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| /* |
| * Ensure the task's vruntime is normalized, so that when its |
| * switched back to the fair class the enqueue_entity(.flags=0) will |
| * do the right thing. |
| * |
| * If it was on_rq, then the dequeue_entity(.flags=0) will already |
| * have normalized the vruntime, if it was !on_rq, then only when |
| * the task is sleeping will it still have non-normalized vruntime. |
| */ |
| if (!se->on_rq && p->state != TASK_RUNNING) { |
| /* |
| * Fix up our vruntime so that the current sleep doesn't |
| * cause 'unlimited' sleep bonus. |
| */ |
| place_entity(cfs_rq, se, 0); |
| se->vruntime -= cfs_rq->min_vruntime; |
| } |
| |
| #ifdef CONFIG_SMP |
| /* |
| * Remove our load from contribution when we leave sched_fair |
| * and ensure we don't carry in an old decay_count if we |
| * switch back. |
| */ |
| if (se->avg.decay_count) { |
| __synchronize_entity_decay(se); |
| subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); |
| } |
| #endif |
| } |
| |
| /* |
| * We switched to the sched_fair class. |
| */ |
| static void switched_to_fair(struct rq *rq, struct task_struct *p) |
| { |
| if (!p->se.on_rq) |
| return; |
| |
| /* |
| * We were most likely switched from sched_rt, so |
| * kick off the schedule if running, otherwise just see |
| * if we can still preempt the current task. |
| */ |
| if (rq->curr == p) |
| resched_task(rq->curr); |
| else |
| check_preempt_curr(rq, p, 0); |
| } |
| |
| /* Account for a task changing its policy or group. |
| * |
| * This routine is mostly called to set cfs_rq->curr field when a task |
| * migrates between groups/classes. |
| */ |
| static void set_curr_task_fair(struct rq *rq) |
| { |
| struct sched_entity *se = &rq->curr->se; |
| |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| set_next_entity(cfs_rq, se); |
| /* ensure bandwidth has been allocated on our new cfs_rq */ |
| account_cfs_rq_runtime(cfs_rq, 0); |
| } |
| } |
| |
| void init_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| cfs_rq->tasks_timeline = RB_ROOT; |
| cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
| #ifndef CONFIG_64BIT |
| cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; |
| #endif |
| #ifdef CONFIG_SMP |
| atomic64_set(&cfs_rq->decay_counter, 1); |
| atomic_long_set(&cfs_rq->removed_load, 0); |
| #endif |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static void task_move_group_fair(struct task_struct *p, int on_rq) |
| { |
| struct cfs_rq *cfs_rq; |
| /* |
| * If the task was not on the rq at the time of this cgroup movement |
| * it must have been asleep, sleeping tasks keep their ->vruntime |
| * absolute on their old rq until wakeup (needed for the fair sleeper |
| * bonus in place_entity()). |
| * |
| * If it was on the rq, we've just 'preempted' it, which does convert |
| * ->vruntime to a relative base. |
| * |
| * Make sure both cases convert their relative position when migrating |
| * to another cgroup's rq. This does somewhat interfere with the |
| * fair sleeper stuff for the first placement, but who cares. |
| */ |
| /* |
| * When !on_rq, vruntime of the task has usually NOT been normalized. |
| * But there are some cases where it has already been normalized: |
| * |
| * - Moving a forked child which is waiting for being woken up by |
| * wake_up_new_task(). |
| * - Moving a task which has been woken up by try_to_wake_up() and |
| * waiting for actually being woken up by sched_ttwu_pending(). |
| * |
| * To prevent boost or penalty in the new cfs_rq caused by delta |
| * min_vruntime between the two cfs_rqs, we skip vruntime adjustment. |
| */ |
| if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING)) |
| on_rq = 1; |
| |
| if (!on_rq) |
| p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime; |
| set_task_rq(p, task_cpu(p)); |
| if (!on_rq) { |
| cfs_rq = cfs_rq_of(&p->se); |
| p->se.vruntime += cfs_rq->min_vruntime; |
| #ifdef CONFIG_SMP |
| /* |
| * migrate_task_rq_fair() will have removed our previous |
| * contribution, but we must synchronize for ongoing future |
| * decay. |
| */ |
| p->se.avg.decay_count = atomic64_read(&cfs_rq->decay_counter); |
| cfs_rq->blocked_load_avg += p->se.avg.load_avg_contrib; |
| #endif |
| } |
| } |
| |
| void free_fair_sched_group(struct task_group *tg) |
| { |
| int i; |
| |
| destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); |
| |
| for_each_possible_cpu(i) { |
| if (tg->cfs_rq) |
| kfree(tg->cfs_rq[i]); |
| if (tg->se) |
| kfree(tg->se[i]); |
| } |
| |
| kfree(tg->cfs_rq); |
| kfree(tg->se); |
| } |
| |
| int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se; |
| int i; |
| |
| tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); |
| if (!tg->cfs_rq) |
| goto err; |
| tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); |
| if (!tg->se) |
| goto err; |
| |
| tg->shares = NICE_0_LOAD; |
| |
| init_cfs_bandwidth(tg_cfs_bandwidth(tg)); |
| |
| for_each_possible_cpu(i) { |
| cfs_rq = kzalloc_node(sizeof(struct cfs_rq), |
| GFP_KERNEL, cpu_to_node(i)); |
| if (!cfs_rq) |
| goto err; |
| |
| se = kzalloc_node(sizeof(struct sched_entity), |
| GFP_KERNEL, cpu_to_node(i)); |
| if (!se) |
| goto err_free_rq; |
| |
| init_cfs_rq(cfs_rq); |
| init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); |
| } |
| |
| return 1; |
| |
| err_free_rq: |
| kfree(cfs_rq); |
| err: |
| return 0; |
| } |
| |
| void unregister_fair_sched_group(struct task_group *tg, int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long flags; |
| |
| /* |
| * Only empty task groups can be destroyed; so we can speculatively |
| * check on_list without danger of it being re-added. |
| */ |
| if (!tg->cfs_rq[cpu]->on_list) |
| return; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, |
| struct sched_entity *se, int cpu, |
| struct sched_entity *parent) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| cfs_rq->tg = tg; |
| cfs_rq->rq = rq; |
| init_cfs_rq_runtime(cfs_rq); |
| |
| tg->cfs_rq[cpu] = cfs_rq; |
| tg->se[cpu] = se; |
| |
| /* se could be NULL for root_task_group */ |
| if (!se) |
| return; |
| |
| if (!parent) |
| se->cfs_rq = &rq->cfs; |
| else |
| se->cfs_rq = parent->my_q; |
| |
| se->my_q = cfs_rq; |
| /* guarantee group entities always have weight */ |
| update_load_set(&se->load, NICE_0_LOAD); |
| se->parent = parent; |
| } |
| |
| static DEFINE_MUTEX(shares_mutex); |
| |
| int sched_group_set_shares(struct task_group *tg, unsigned long shares) |
| { |
| int i; |
| unsigned long flags; |
| |
| /* |
| * We can't change the weight of the root cgroup. |
| */ |
| if (!tg->se[0]) |
| return -EINVAL; |
| |
| shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); |
| |
| mutex_lock(&shares_mutex); |
| if (tg->shares == shares) |
| goto done; |
| |
| tg->shares = shares; |
| for_each_possible_cpu(i) { |
| struct rq *rq = cpu_rq(i); |
| struct sched_entity *se; |
| |
| se = tg->se[i]; |
| /* Propagate contribution to hierarchy */ |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| |
| /* Possible calls to update_curr() need rq clock */ |
| update_rq_clock(rq); |
| for_each_sched_entity(se) |
| update_cfs_shares(group_cfs_rq(se)); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| done: |
| mutex_unlock(&shares_mutex); |
| return 0; |
| } |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| void free_fair_sched_group(struct task_group *tg) { } |
| |
| int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) |
| { |
| return 1; |
| } |
| |
| void unregister_fair_sched_group(struct task_group *tg, int cpu) { } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| |
| static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
| { |
| struct sched_entity *se = &task->se; |
| unsigned int rr_interval = 0; |
| |
| /* |
| * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise |
| * idle runqueue: |
| */ |
| if (rq->cfs.load.weight) |
| rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
| |
| return rr_interval; |
| } |
| |
| /* |
| * All the scheduling class methods: |
| */ |
| const struct sched_class fair_sched_class = { |
| .next = &idle_sched_class, |
| .enqueue_task = enqueue_task_fair, |
| .dequeue_task = dequeue_task_fair, |
| .yield_task = yield_task_fair, |
| .yield_to_task = yield_to_task_fair, |
| |
| .check_preempt_curr = check_preempt_wakeup, |
| |
| .pick_next_task = pick_next_task_fair, |
| .put_prev_task = put_prev_task_fair, |
| |
| #ifdef CONFIG_SMP |
| .select_task_rq = select_task_rq_fair, |
| .migrate_task_rq = migrate_task_rq_fair, |
| |
| .rq_online = rq_online_fair, |
| .rq_offline = rq_offline_fair, |
| |
| .task_waking = task_waking_fair, |
| #endif |
| |
| .set_curr_task = set_curr_task_fair, |
| .task_tick = task_tick_fair, |
| .task_fork = task_fork_fair, |
| |
| .prio_changed = prio_changed_fair, |
| .switched_from = switched_from_fair, |
| .switched_to = switched_to_fair, |
| |
| .get_rr_interval = get_rr_interval_fair, |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| .task_move_group = task_move_group_fair, |
| #endif |
| }; |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| void print_cfs_stats(struct seq_file *m, int cpu) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| rcu_read_lock(); |
| for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
| print_cfs_rq(m, cpu, cfs_rq); |
| rcu_read_unlock(); |
| } |
| #endif |
| |
| __init void init_sched_fair_class(void) |
| { |
| #ifdef CONFIG_SMP |
| open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| nohz.next_balance = jiffies; |
| zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
| cpu_notifier(sched_ilb_notifier, 0); |
| #endif |
| #endif /* SMP */ |
| |
| } |