sched: revert revert of: fair-group: SMP-nice for group scheduling
Try again..
Initial commit: 18d95a2832c1392a2d63227a7a6d433cb9f2037e
Revert: 6363ca57c76b7b83639ca8c83fc285fa26a7880e
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index f653af6..874b6da 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -403,6 +403,43 @@
*/
struct list_head leaf_cfs_rq_list;
struct task_group *tg; /* group that "owns" this runqueue */
+
+#ifdef CONFIG_SMP
+ unsigned long task_weight;
+ unsigned long shares;
+ /*
+ * We need space to build a sched_domain wide view of the full task
+ * group tree, in order to avoid depending on dynamic memory allocation
+ * during the load balancing we place this in the per cpu task group
+ * hierarchy. This limits the load balancing to one instance per cpu,
+ * but more should not be needed anyway.
+ */
+ struct aggregate_struct {
+ /*
+ * load = weight(cpus) * f(tg)
+ *
+ * Where f(tg) is the recursive weight fraction assigned to
+ * this group.
+ */
+ unsigned long load;
+
+ /*
+ * part of the group weight distributed to this span.
+ */
+ unsigned long shares;
+
+ /*
+ * The sum of all runqueue weights within this span.
+ */
+ unsigned long rq_weight;
+
+ /*
+ * Weight contributed by tasks; this is the part we can
+ * influence by moving tasks around.
+ */
+ unsigned long task_weight;
+ } aggregate;
+#endif
#endif
};
@@ -1484,6 +1521,326 @@
static unsigned long target_load(int cpu, int type);
static unsigned long cpu_avg_load_per_task(int cpu);
static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/*
+ * Group load balancing.
+ *
+ * We calculate a few balance domain wide aggregate numbers; load and weight.
+ * Given the pictures below, and assuming each item has equal weight:
+ *
+ * root 1 - thread
+ * / | \ A - group
+ * A 1 B
+ * /|\ / \
+ * C 2 D 3 4
+ * | |
+ * 5 6
+ *
+ * load:
+ * A and B get 1/3-rd of the total load. C and D get 1/3-rd of A's 1/3-rd,
+ * which equals 1/9-th of the total load.
+ *
+ * shares:
+ * The weight of this group on the selected cpus.
+ *
+ * rq_weight:
+ * Direct sum of all the cpu's their rq weight, e.g. A would get 3 while
+ * B would get 2.
+ *
+ * task_weight:
+ * Part of the rq_weight contributed by tasks; all groups except B would
+ * get 1, B gets 2.
+ */
+
+static inline struct aggregate_struct *
+aggregate(struct task_group *tg, struct sched_domain *sd)
+{
+ return &tg->cfs_rq[sd->first_cpu]->aggregate;
+}
+
+typedef void (*aggregate_func)(struct task_group *, struct sched_domain *);
+
+/*
+ * Iterate the full tree, calling @down when first entering a node and @up when
+ * leaving it for the final time.
+ */
+static
+void aggregate_walk_tree(aggregate_func down, aggregate_func up,
+ struct sched_domain *sd)
+{
+ struct task_group *parent, *child;
+
+ rcu_read_lock();
+ parent = &root_task_group;
+down:
+ (*down)(parent, sd);
+ list_for_each_entry_rcu(child, &parent->children, siblings) {
+ parent = child;
+ goto down;
+
+up:
+ continue;
+ }
+ (*up)(parent, sd);
+
+ child = parent;
+ parent = parent->parent;
+ if (parent)
+ goto up;
+ rcu_read_unlock();
+}
+
+/*
+ * Calculate the aggregate runqueue weight.
+ */
+static
+void aggregate_group_weight(struct task_group *tg, struct sched_domain *sd)
+{
+ unsigned long rq_weight = 0;
+ unsigned long task_weight = 0;
+ int i;
+
+ for_each_cpu_mask(i, sd->span) {
+ rq_weight += tg->cfs_rq[i]->load.weight;
+ task_weight += tg->cfs_rq[i]->task_weight;
+ }
+
+ aggregate(tg, sd)->rq_weight = rq_weight;
+ aggregate(tg, sd)->task_weight = task_weight;
+}
+
+/*
+ * Compute the weight of this group on the given cpus.
+ */
+static
+void aggregate_group_shares(struct task_group *tg, struct sched_domain *sd)
+{
+ unsigned long shares = 0;
+ int i;
+
+ for_each_cpu_mask(i, sd->span)
+ shares += tg->cfs_rq[i]->shares;
+
+ if ((!shares && aggregate(tg, sd)->rq_weight) || shares > tg->shares)
+ shares = tg->shares;
+
+ aggregate(tg, sd)->shares = shares;
+}
+
+/*
+ * Compute the load fraction assigned to this group, relies on the aggregate
+ * weight and this group's parent's load, i.e. top-down.
+ */
+static
+void aggregate_group_load(struct task_group *tg, struct sched_domain *sd)
+{
+ unsigned long load;
+
+ if (!tg->parent) {
+ int i;
+
+ load = 0;
+ for_each_cpu_mask(i, sd->span)
+ load += cpu_rq(i)->load.weight;
+
+ } else {
+ load = aggregate(tg->parent, sd)->load;
+
+ /*
+ * shares is our weight in the parent's rq so
+ * shares/parent->rq_weight gives our fraction of the load
+ */
+ load *= aggregate(tg, sd)->shares;
+ load /= aggregate(tg->parent, sd)->rq_weight + 1;
+ }
+
+ aggregate(tg, sd)->load = load;
+}
+
+static void __set_se_shares(struct sched_entity *se, unsigned long shares);
+
+/*
+ * Calculate and set the cpu's group shares.
+ */
+static void
+__update_group_shares_cpu(struct task_group *tg, struct sched_domain *sd,
+ int tcpu)
+{
+ int boost = 0;
+ unsigned long shares;
+ unsigned long rq_weight;
+
+ if (!tg->se[tcpu])
+ return;
+
+ rq_weight = tg->cfs_rq[tcpu]->load.weight;
+
+ /*
+ * If there are currently no tasks on the cpu pretend there is one of
+ * average load so that when a new task gets to run here it will not
+ * get delayed by group starvation.
+ */
+ if (!rq_weight) {
+ boost = 1;
+ rq_weight = NICE_0_LOAD;
+ }
+
+ /*
+ * \Sum shares * rq_weight
+ * shares = -----------------------
+ * \Sum rq_weight
+ *
+ */
+ shares = aggregate(tg, sd)->shares * rq_weight;
+ shares /= aggregate(tg, sd)->rq_weight + 1;
+
+ /*
+ * record the actual number of shares, not the boosted amount.
+ */
+ tg->cfs_rq[tcpu]->shares = boost ? 0 : shares;
+
+ if (shares < MIN_SHARES)
+ shares = MIN_SHARES;
+ else if (shares > MAX_SHARES)
+ shares = MAX_SHARES;
+
+ __set_se_shares(tg->se[tcpu], shares);
+}
+
+/*
+ * Re-adjust the weights on the cpu the task came from and on the cpu the
+ * task went to.
+ */
+static void
+__move_group_shares(struct task_group *tg, struct sched_domain *sd,
+ int scpu, int dcpu)
+{
+ unsigned long shares;
+
+ shares = tg->cfs_rq[scpu]->shares + tg->cfs_rq[dcpu]->shares;
+
+ __update_group_shares_cpu(tg, sd, scpu);
+ __update_group_shares_cpu(tg, sd, dcpu);
+
+ /*
+ * ensure we never loose shares due to rounding errors in the
+ * above redistribution.
+ */
+ shares -= tg->cfs_rq[scpu]->shares + tg->cfs_rq[dcpu]->shares;
+ if (shares)
+ tg->cfs_rq[dcpu]->shares += shares;
+}
+
+/*
+ * Because changing a group's shares changes the weight of the super-group
+ * we need to walk up the tree and change all shares until we hit the root.
+ */
+static void
+move_group_shares(struct task_group *tg, struct sched_domain *sd,
+ int scpu, int dcpu)
+{
+ while (tg) {
+ __move_group_shares(tg, sd, scpu, dcpu);
+ tg = tg->parent;
+ }
+}
+
+static
+void aggregate_group_set_shares(struct task_group *tg, struct sched_domain *sd)
+{
+ unsigned long shares = aggregate(tg, sd)->shares;
+ int i;
+
+ for_each_cpu_mask(i, sd->span) {
+ struct rq *rq = cpu_rq(i);
+ unsigned long flags;
+
+ spin_lock_irqsave(&rq->lock, flags);
+ __update_group_shares_cpu(tg, sd, i);
+ spin_unlock_irqrestore(&rq->lock, flags);
+ }
+
+ aggregate_group_shares(tg, sd);
+
+ /*
+ * ensure we never loose shares due to rounding errors in the
+ * above redistribution.
+ */
+ shares -= aggregate(tg, sd)->shares;
+ if (shares) {
+ tg->cfs_rq[sd->first_cpu]->shares += shares;
+ aggregate(tg, sd)->shares += shares;
+ }
+}
+
+/*
+ * Calculate the accumulative weight and recursive load of each task group
+ * while walking down the tree.
+ */
+static
+void aggregate_get_down(struct task_group *tg, struct sched_domain *sd)
+{
+ aggregate_group_weight(tg, sd);
+ aggregate_group_shares(tg, sd);
+ aggregate_group_load(tg, sd);
+}
+
+/*
+ * Rebalance the cpu shares while walking back up the tree.
+ */
+static
+void aggregate_get_up(struct task_group *tg, struct sched_domain *sd)
+{
+ aggregate_group_set_shares(tg, sd);
+}
+
+static DEFINE_PER_CPU(spinlock_t, aggregate_lock);
+
+static void __init init_aggregate(void)
+{
+ int i;
+
+ for_each_possible_cpu(i)
+ spin_lock_init(&per_cpu(aggregate_lock, i));
+}
+
+static int get_aggregate(struct sched_domain *sd)
+{
+ if (!spin_trylock(&per_cpu(aggregate_lock, sd->first_cpu)))
+ return 0;
+
+ aggregate_walk_tree(aggregate_get_down, aggregate_get_up, sd);
+ return 1;
+}
+
+static void put_aggregate(struct sched_domain *sd)
+{
+ spin_unlock(&per_cpu(aggregate_lock, sd->first_cpu));
+}
+
+static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
+{
+ cfs_rq->shares = shares;
+}
+
+#else
+
+static inline void init_aggregate(void)
+{
+}
+
+static inline int get_aggregate(struct sched_domain *sd)
+{
+ return 0;
+}
+
+static inline void put_aggregate(struct sched_domain *sd)
+{
+}
+#endif
+
#endif
#include "sched_stats.h"
@@ -1498,26 +1855,14 @@
#define for_each_class(class) \
for (class = sched_class_highest; class; class = class->next)
-static inline void inc_load(struct rq *rq, const struct task_struct *p)
-{
- update_load_add(&rq->load, p->se.load.weight);
-}
-
-static inline void dec_load(struct rq *rq, const struct task_struct *p)
-{
- update_load_sub(&rq->load, p->se.load.weight);
-}
-
-static void inc_nr_running(struct task_struct *p, struct rq *rq)
+static void inc_nr_running(struct rq *rq)
{
rq->nr_running++;
- inc_load(rq, p);
}
-static void dec_nr_running(struct task_struct *p, struct rq *rq)
+static void dec_nr_running(struct rq *rq)
{
rq->nr_running--;
- dec_load(rq, p);
}
static void set_load_weight(struct task_struct *p)
@@ -1609,7 +1954,7 @@
rq->nr_uninterruptible--;
enqueue_task(rq, p, wakeup);
- inc_nr_running(p, rq);
+ inc_nr_running(rq);
}
/*
@@ -1621,7 +1966,7 @@
rq->nr_uninterruptible++;
dequeue_task(rq, p, sleep);
- dec_nr_running(p, rq);
+ dec_nr_running(rq);
}
/**
@@ -2274,7 +2619,7 @@
* management (if any):
*/
p->sched_class->task_new(rq, p);
- inc_nr_running(p, rq);
+ inc_nr_running(rq);
}
check_preempt_curr(rq, p);
#ifdef CONFIG_SMP
@@ -3265,9 +3610,12 @@
unsigned long imbalance;
struct rq *busiest;
unsigned long flags;
+ int unlock_aggregate;
cpus_setall(*cpus);
+ unlock_aggregate = get_aggregate(sd);
+
/*
* When power savings policy is enabled for the parent domain, idle
* sibling can pick up load irrespective of busy siblings. In this case,
@@ -3383,8 +3731,9 @@
if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- return -1;
- return ld_moved;
+ ld_moved = -1;
+
+ goto out;
out_balanced:
schedstat_inc(sd, lb_balanced[idle]);
@@ -3399,8 +3748,13 @@
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
- return -1;
- return 0;
+ ld_moved = -1;
+ else
+ ld_moved = 0;
+out:
+ if (unlock_aggregate)
+ put_aggregate(sd);
+ return ld_moved;
}
/*
@@ -4588,10 +4942,8 @@
goto out_unlock;
}
on_rq = p->se.on_rq;
- if (on_rq) {
+ if (on_rq)
dequeue_task(rq, p, 0);
- dec_load(rq, p);
- }
p->static_prio = NICE_TO_PRIO(nice);
set_load_weight(p);
@@ -4601,7 +4953,6 @@
if (on_rq) {
enqueue_task(rq, p, 0);
- inc_load(rq, p);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
@@ -7016,6 +7367,7 @@
SD_INIT(sd, ALLNODES);
set_domain_attribute(sd, attr);
sd->span = *cpu_map;
+ sd->first_cpu = first_cpu(sd->span);
cpu_to_allnodes_group(i, cpu_map, &sd->groups, tmpmask);
p = sd;
sd_allnodes = 1;
@@ -7026,6 +7378,7 @@
SD_INIT(sd, NODE);
set_domain_attribute(sd, attr);
sched_domain_node_span(cpu_to_node(i), &sd->span);
+ sd->first_cpu = first_cpu(sd->span);
sd->parent = p;
if (p)
p->child = sd;
@@ -7037,6 +7390,7 @@
SD_INIT(sd, CPU);
set_domain_attribute(sd, attr);
sd->span = *nodemask;
+ sd->first_cpu = first_cpu(sd->span);
sd->parent = p;
if (p)
p->child = sd;
@@ -7048,6 +7402,7 @@
SD_INIT(sd, MC);
set_domain_attribute(sd, attr);
sd->span = cpu_coregroup_map(i);
+ sd->first_cpu = first_cpu(sd->span);
cpus_and(sd->span, sd->span, *cpu_map);
sd->parent = p;
p->child = sd;
@@ -7060,6 +7415,7 @@
SD_INIT(sd, SIBLING);
set_domain_attribute(sd, attr);
sd->span = per_cpu(cpu_sibling_map, i);
+ sd->first_cpu = first_cpu(sd->span);
cpus_and(sd->span, sd->span, *cpu_map);
sd->parent = p;
p->child = sd;
@@ -7757,6 +8113,7 @@
}
#ifdef CONFIG_SMP
+ init_aggregate();
init_defrootdomain();
#endif
@@ -8322,14 +8679,11 @@
#endif /* CONFIG_GROUP_SCHED */
#ifdef CONFIG_FAIR_GROUP_SCHED
-static void set_se_shares(struct sched_entity *se, unsigned long shares)
+static void __set_se_shares(struct sched_entity *se, unsigned long shares)
{
struct cfs_rq *cfs_rq = se->cfs_rq;
- struct rq *rq = cfs_rq->rq;
int on_rq;
- spin_lock_irq(&rq->lock);
-
on_rq = se->on_rq;
if (on_rq)
dequeue_entity(cfs_rq, se, 0);
@@ -8339,8 +8693,17 @@
if (on_rq)
enqueue_entity(cfs_rq, se, 0);
+}
- spin_unlock_irq(&rq->lock);
+static void set_se_shares(struct sched_entity *se, unsigned long shares)
+{
+ struct cfs_rq *cfs_rq = se->cfs_rq;
+ struct rq *rq = cfs_rq->rq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&rq->lock, flags);
+ __set_se_shares(se, shares);
+ spin_unlock_irqrestore(&rq->lock, flags);
}
static DEFINE_MUTEX(shares_mutex);
@@ -8379,8 +8742,13 @@
* w/o tripping rebalance_share or load_balance_fair.
*/
tg->shares = shares;
- for_each_possible_cpu(i)
+ for_each_possible_cpu(i) {
+ /*
+ * force a rebalance
+ */
+ cfs_rq_set_shares(tg->cfs_rq[i], 0);
set_se_shares(tg->se[i], shares);
+ }
/*
* Enable load balance activity on this group, by inserting it back on
