| /* |
| * 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> |
| */ |
| |
| /* |
| * Targeted preemption latency for CPU-bound tasks: |
| * (default: 20ms, 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) |
| */ |
| const_debug unsigned int sysctl_sched_latency = 20000000ULL; |
| |
| /* |
| * After fork, child runs first. (default) If set to 0 then |
| * parent will (try to) run first. |
| */ |
| const_debug unsigned int sysctl_sched_child_runs_first = 1; |
| |
| /* |
| * Minimal preemption granularity for CPU-bound tasks: |
| * (default: 2 msec, units: nanoseconds) |
| */ |
| const_debug unsigned int sysctl_sched_nr_latency = 20; |
| |
| /* |
| * sys_sched_yield() compat mode |
| * |
| * This option switches the agressive yield implementation of the |
| * old scheduler back on. |
| */ |
| unsigned int __read_mostly sysctl_sched_compat_yield; |
| |
| /* |
| * SCHED_BATCH wake-up granularity. |
| * (default: 10 msec, 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. |
| */ |
| const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL; |
| |
| /* |
| * SCHED_OTHER wake-up granularity. |
| * (default: 10 msec, 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. |
| */ |
| const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL; |
| |
| const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
| |
| /************************************************************** |
| * 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) |
| |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| 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 |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| return container_of(se, struct task_struct, se); |
| } |
| |
| |
| /************************************************************** |
| * Scheduling class tree data structure manipulation methods: |
| */ |
| |
| static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - min_vruntime); |
| if (delta > 0) |
| min_vruntime = vruntime; |
| |
| return min_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 s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return se->vruntime - cfs_rq->min_vruntime; |
| } |
| |
| /* |
| * 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; |
| s64 key = entity_key(cfs_rq, se); |
| 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 (key < entity_key(cfs_rq, 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) |
| cfs_rq->rb_leftmost = rb_next(&se->run_node); |
| |
| rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->rb_leftmost; |
| } |
| |
| static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node); |
| } |
| |
| static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; |
| struct sched_entity *se = NULL; |
| struct rb_node *parent; |
| |
| while (*link) { |
| parent = *link; |
| se = rb_entry(parent, struct sched_entity, run_node); |
| link = &parent->rb_right; |
| } |
| |
| return se; |
| } |
| |
| /************************************************************** |
| * Scheduling class statistics methods: |
| */ |
| |
| |
| /* |
| * The idea is to set a period in which each task runs once. |
| * |
| * When there are too many tasks (sysctl_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 = sysctl_sched_nr_latency; |
| |
| if (unlikely(nr_running > nr_latency)) { |
| period *= nr_running; |
| do_div(period, nr_latency); |
| } |
| |
| return period; |
| } |
| |
| /* |
| * We calculate the wall-time slice from the period by taking a part |
| * proportional to the weight. |
| * |
| * s = p*w/rw |
| */ |
| static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| u64 slice = __sched_period(cfs_rq->nr_running); |
| |
| slice *= se->load.weight; |
| do_div(slice, cfs_rq->load.weight); |
| |
| return slice; |
| } |
| |
| /* |
| * We calculate the vruntime slice. |
| * |
| * vs = s/w = p/rw |
| */ |
| static u64 __sched_vslice(unsigned long rq_weight, unsigned long nr_running) |
| { |
| u64 vslice = __sched_period(nr_running); |
| |
| do_div(vslice, rq_weight); |
| |
| return vslice; |
| } |
| |
| static u64 sched_vslice(struct cfs_rq *cfs_rq) |
| { |
| return __sched_vslice(cfs_rq->load.weight, cfs_rq->nr_running); |
| } |
| |
| static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return __sched_vslice(cfs_rq->load.weight + se->load.weight, |
| cfs_rq->nr_running + 1); |
| } |
| |
| /* |
| * Update the current task's runtime statistics. Skip current tasks that |
| * are not in our scheduling class. |
| */ |
| static inline void |
| __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, |
| unsigned long delta_exec) |
| { |
| unsigned long delta_exec_weighted; |
| u64 vruntime; |
| |
| schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max)); |
| |
| curr->sum_exec_runtime += delta_exec; |
| schedstat_add(cfs_rq, exec_clock, delta_exec); |
| delta_exec_weighted = delta_exec; |
| if (unlikely(curr->load.weight != NICE_0_LOAD)) { |
| delta_exec_weighted = calc_delta_fair(delta_exec_weighted, |
| &curr->load); |
| } |
| curr->vruntime += delta_exec_weighted; |
| |
| /* |
| * maintain cfs_rq->min_vruntime to be a monotonic increasing |
| * value tracking the leftmost vruntime in the tree. |
| */ |
| if (first_fair(cfs_rq)) { |
| vruntime = min_vruntime(curr->vruntime, |
| __pick_next_entity(cfs_rq)->vruntime); |
| } else |
| vruntime = curr->vruntime; |
| |
| cfs_rq->min_vruntime = |
| max_vruntime(cfs_rq->min_vruntime, vruntime); |
| } |
| |
| static void update_curr(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq->curr; |
| u64 now = rq_of(cfs_rq)->clock; |
| unsigned long delta_exec; |
| |
| if (unlikely(!curr)) |
| return; |
| |
| /* |
| * Get the amount of time the current task was running |
| * since the last time we changed load (this cannot |
| * overflow on 32 bits): |
| */ |
| delta_exec = (unsigned long)(now - curr->exec_start); |
| |
| __update_curr(cfs_rq, curr, delta_exec); |
| curr->exec_start = now; |
| } |
| |
| static inline void |
| update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| schedstat_set(se->wait_start, rq_of(cfs_rq)->clock); |
| } |
| |
| /* |
| * 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->wait_max, max(se->wait_max, |
| rq_of(cfs_rq)->clock - se->wait_start)); |
| schedstat_set(se->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_of(cfs_rq)->clock; |
| } |
| |
| /************************************************** |
| * Scheduling class queueing methods: |
| */ |
| |
| static void |
| account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_add(&cfs_rq->load, se->load.weight); |
| cfs_rq->nr_running++; |
| se->on_rq = 1; |
| } |
| |
| static void |
| account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_sub(&cfs_rq->load, se->load.weight); |
| cfs_rq->nr_running--; |
| se->on_rq = 0; |
| } |
| |
| static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHEDSTATS |
| if (se->sleep_start) { |
| u64 delta = rq_of(cfs_rq)->clock - se->sleep_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->sleep_max)) |
| se->sleep_max = delta; |
| |
| se->sleep_start = 0; |
| se->sum_sleep_runtime += delta; |
| } |
| if (se->block_start) { |
| u64 delta = rq_of(cfs_rq)->clock - se->block_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->block_max)) |
| se->block_max = delta; |
| |
| se->block_start = 0; |
| se->sum_sleep_runtime += 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)) { |
| struct task_struct *tsk = task_of(se); |
| |
| profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk), |
| delta >> 20); |
| } |
| } |
| #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; |
| |
| vruntime = cfs_rq->min_vruntime; |
| |
| if (sched_feat(TREE_AVG)) { |
| struct sched_entity *last = __pick_last_entity(cfs_rq); |
| if (last) { |
| vruntime += last->vruntime; |
| vruntime >>= 1; |
| } |
| } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running) |
| vruntime += sched_vslice(cfs_rq)/2; |
| |
| if (initial && sched_feat(START_DEBIT)) |
| vruntime += sched_vslice_add(cfs_rq, se); |
| |
| if (!initial) { |
| if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se) && |
| task_of(se)->policy != SCHED_BATCH) |
| vruntime -= sysctl_sched_latency; |
| |
| vruntime = max_t(s64, vruntime, se->vruntime); |
| } |
| |
| se->vruntime = vruntime; |
| |
| } |
| |
| static void |
| enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| if (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); |
| account_entity_enqueue(cfs_rq, se); |
| } |
| |
| static void |
| dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| update_stats_dequeue(cfs_rq, se); |
| if (sleep) { |
| se->peer_preempt = 0; |
| #ifdef CONFIG_SCHEDSTATS |
| if (entity_is_task(se)) { |
| struct task_struct *tsk = task_of(se); |
| |
| if (tsk->state & TASK_INTERRUPTIBLE) |
| se->sleep_start = rq_of(cfs_rq)->clock; |
| if (tsk->state & TASK_UNINTERRUPTIBLE) |
| se->block_start = rq_of(cfs_rq)->clock; |
| } |
| #endif |
| } |
| |
| if (se != cfs_rq->curr) |
| __dequeue_entity(cfs_rq, se); |
| account_entity_dequeue(cfs_rq, se); |
| } |
| |
| /* |
| * 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; |
| |
| ideal_runtime = sched_slice(cfs_rq, curr); |
| delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
| if (delta_exec > ideal_runtime || |
| (sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt)) |
| resched_task(rq_of(cfs_rq)->curr); |
| curr->peer_preempt = 0; |
| } |
| |
| 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->slice_max = max(se->slice_max, |
| se->sum_exec_runtime - se->prev_sum_exec_runtime); |
| } |
| #endif |
| se->prev_sum_exec_runtime = se->sum_exec_runtime; |
| } |
| |
| static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *se = NULL; |
| |
| if (first_fair(cfs_rq)) { |
| se = __pick_next_entity(cfs_rq); |
| set_next_entity(cfs_rq, se); |
| } |
| |
| return se; |
| } |
| |
| 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); |
| |
| 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); |
| } |
| cfs_rq->curr = NULL; |
| } |
| |
| static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT)) |
| check_preempt_tick(cfs_rq, curr); |
| } |
| |
| /************************************************** |
| * CFS operations on tasks: |
| */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| /* 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; |
| } |
| |
| /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on |
| * another cpu ('this_cpu') |
| */ |
| static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) |
| { |
| return cfs_rq->tg->cfs_rq[this_cpu]; |
| } |
| |
| /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| list_for_each_entry(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; |
| } |
| |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| #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 struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) |
| { |
| return &cpu_rq(this_cpu)->cfs; |
| } |
| |
| #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; |
| } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| /* |
| * 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 wakeup) |
| { |
| 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, wakeup); |
| wakeup = 1; |
| } |
| } |
| |
| /* |
| * 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 sleep) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| dequeue_entity(cfs_rq, se, sleep); |
| /* Don't dequeue parent if it has other entities besides us */ |
| if (cfs_rq->load.weight) |
| break; |
| sleep = 1; |
| } |
| } |
| |
| /* |
| * sched_yield() support is very simple - we dequeue and enqueue. |
| * |
| * If compat_yield is turned on then we requeue to the end of the tree. |
| */ |
| static void yield_task_fair(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(rq->curr); |
| struct sched_entity *rightmost, *se = &rq->curr->se; |
| |
| /* |
| * Are we the only task in the tree? |
| */ |
| if (unlikely(cfs_rq->nr_running == 1)) |
| return; |
| |
| if (likely(!sysctl_sched_compat_yield)) { |
| __update_rq_clock(rq); |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| return; |
| } |
| /* |
| * Find the rightmost entry in the rbtree: |
| */ |
| rightmost = __pick_last_entity(cfs_rq); |
| /* |
| * Already in the rightmost position? |
| */ |
| if (unlikely(rightmost->vruntime < se->vruntime)) |
| return; |
| |
| /* |
| * Minimally necessary key value to be last in the tree: |
| * Upon rescheduling, sched_class::put_prev_task() will place |
| * 'current' within the tree based on its new key value. |
| */ |
| se->vruntime = rightmost->vruntime + 1; |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) |
| { |
| struct task_struct *curr = rq->curr; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| struct sched_entity *se = &curr->se, *pse = &p->se; |
| s64 delta, gran; |
| |
| if (unlikely(rt_prio(p->prio))) { |
| update_rq_clock(rq); |
| update_curr(cfs_rq); |
| resched_task(curr); |
| return; |
| } |
| /* |
| * Batch tasks do not preempt (their preemption is driven by |
| * the tick): |
| */ |
| if (unlikely(p->policy == SCHED_BATCH)) |
| return; |
| |
| if (sched_feat(WAKEUP_PREEMPT)) { |
| while (!is_same_group(se, pse)) { |
| se = parent_entity(se); |
| pse = parent_entity(pse); |
| } |
| |
| delta = se->vruntime - pse->vruntime; |
| gran = sysctl_sched_wakeup_granularity; |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| gran = calc_delta_fair(gran, &se->load); |
| |
| if (delta > gran) { |
| int now = !sched_feat(PREEMPT_RESTRICT); |
| |
| if (now || p->prio < curr->prio || !se->peer_preempt++) |
| resched_task(curr); |
| } |
| } |
| } |
| |
| static struct task_struct *pick_next_task_fair(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq = &rq->cfs; |
| struct sched_entity *se; |
| |
| if (unlikely(!cfs_rq->nr_running)) |
| return NULL; |
| |
| do { |
| se = pick_next_entity(cfs_rq); |
| cfs_rq = group_cfs_rq(se); |
| } while (cfs_rq); |
| |
| return task_of(se); |
| } |
| |
| /* |
| * 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); |
| } |
| } |
| |
| /************************************************** |
| * Fair scheduling class load-balancing methods: |
| */ |
| |
| /* |
| * Load-balancing iterator. Note: while the runqueue stays locked |
| * during the whole iteration, the current task might be |
| * dequeued so the iterator has to be dequeue-safe. Here we |
| * achieve that by always pre-iterating before returning |
| * the current task: |
| */ |
| static struct task_struct * |
| __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr) |
| { |
| struct task_struct *p; |
| |
| if (!curr) |
| return NULL; |
| |
| p = rb_entry(curr, struct task_struct, se.run_node); |
| cfs_rq->rb_load_balance_curr = rb_next(curr); |
| |
| return p; |
| } |
| |
| static struct task_struct *load_balance_start_fair(void *arg) |
| { |
| struct cfs_rq *cfs_rq = arg; |
| |
| return __load_balance_iterator(cfs_rq, first_fair(cfs_rq)); |
| } |
| |
| static struct task_struct *load_balance_next_fair(void *arg) |
| { |
| struct cfs_rq *cfs_rq = arg; |
| |
| return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr); |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static int cfs_rq_best_prio(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr; |
| struct task_struct *p; |
| |
| if (!cfs_rq->nr_running) |
| return MAX_PRIO; |
| |
| curr = cfs_rq->curr; |
| if (!curr) |
| curr = __pick_next_entity(cfs_rq); |
| |
| p = task_of(curr); |
| |
| return p->prio; |
| } |
| #endif |
| |
| static unsigned long |
| load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, |
| unsigned long max_load_move, |
| struct sched_domain *sd, enum cpu_idle_type idle, |
| int *all_pinned, int *this_best_prio) |
| { |
| struct cfs_rq *busy_cfs_rq; |
| long rem_load_move = max_load_move; |
| struct rq_iterator cfs_rq_iterator; |
| |
| cfs_rq_iterator.start = load_balance_start_fair; |
| cfs_rq_iterator.next = load_balance_next_fair; |
| |
| for_each_leaf_cfs_rq(busiest, busy_cfs_rq) { |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| struct cfs_rq *this_cfs_rq; |
| long imbalance; |
| unsigned long maxload; |
| |
| this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu); |
| |
| imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight; |
| /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */ |
| if (imbalance <= 0) |
| continue; |
| |
| /* Don't pull more than imbalance/2 */ |
| imbalance /= 2; |
| maxload = min(rem_load_move, imbalance); |
| |
| *this_best_prio = cfs_rq_best_prio(this_cfs_rq); |
| #else |
| # define maxload rem_load_move |
| #endif |
| /* |
| * pass busy_cfs_rq argument into |
| * load_balance_[start|next]_fair iterators |
| */ |
| cfs_rq_iterator.arg = busy_cfs_rq; |
| rem_load_move -= balance_tasks(this_rq, this_cpu, busiest, |
| maxload, sd, idle, all_pinned, |
| this_best_prio, |
| &cfs_rq_iterator); |
| |
| if (rem_load_move <= 0) |
| break; |
| } |
| |
| return max_load_move - rem_load_move; |
| } |
| |
| static int |
| move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, |
| struct sched_domain *sd, enum cpu_idle_type idle) |
| { |
| struct cfs_rq *busy_cfs_rq; |
| struct rq_iterator cfs_rq_iterator; |
| |
| cfs_rq_iterator.start = load_balance_start_fair; |
| cfs_rq_iterator.next = load_balance_next_fair; |
| |
| for_each_leaf_cfs_rq(busiest, busy_cfs_rq) { |
| /* |
| * pass busy_cfs_rq argument into |
| * load_balance_[start|next]_fair iterators |
| */ |
| cfs_rq_iterator.arg = busy_cfs_rq; |
| if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle, |
| &cfs_rq_iterator)) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * scheduler tick hitting a task of our scheduling class: |
| */ |
| static void task_tick_fair(struct rq *rq, struct task_struct *curr) |
| { |
| 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); |
| } |
| } |
| |
| #define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0) |
| |
| /* |
| * Share the fairness runtime between parent and child, thus the |
| * total amount of pressure for CPU stays equal - new tasks |
| * get a chance to run but frequent forkers are not allowed to |
| * monopolize the CPU. Note: the parent runqueue is locked, |
| * the child is not running yet. |
| */ |
| static void task_new_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(p); |
| struct sched_entity *se = &p->se, *curr = cfs_rq->curr; |
| int this_cpu = smp_processor_id(); |
| |
| sched_info_queued(p); |
| |
| update_curr(cfs_rq); |
| place_entity(cfs_rq, se, 1); |
| |
| if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) && |
| curr->vruntime < se->vruntime) { |
| /* |
| * Upon rescheduling, sched_class::put_prev_task() will place |
| * 'current' within the tree based on its new key value. |
| */ |
| swap(curr->vruntime, se->vruntime); |
| } |
| |
| se->peer_preempt = 0; |
| enqueue_task_fair(rq, p, 0); |
| resched_task(rq->curr); |
| } |
| |
| /* 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) |
| set_next_entity(cfs_rq_of(se), se); |
| } |
| |
| /* |
| * All the scheduling class methods: |
| */ |
| static 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, |
| |
| .check_preempt_curr = check_preempt_wakeup, |
| |
| .pick_next_task = pick_next_task_fair, |
| .put_prev_task = put_prev_task_fair, |
| |
| .load_balance = load_balance_fair, |
| .move_one_task = move_one_task_fair, |
| |
| .set_curr_task = set_curr_task_fair, |
| .task_tick = task_tick_fair, |
| .task_new = task_new_fair, |
| }; |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| static void print_cfs_stats(struct seq_file *m, int cpu) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| print_cfs_rq(m, cpu, &cpu_rq(cpu)->cfs); |
| #endif |
| for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
| print_cfs_rq(m, cpu, cfs_rq); |
| } |
| #endif |