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sched: add avg_overlap decay
Impact: more precise avg_overlap metric - better load-balancing avg_overlap is used to measure the runtime overlap of the waker and wakee. However, when a process changes behaviour, eg a pipe becomes un-congested and we don't need to go to sleep after a wakeup for a while, the avg_overlap value grows stale. When running we use the avg runtime between preemption as a measure for avg_overlap since the amount of runtime can be correlated to cache footprint. The longer we run, the less likely we'll be wanting to be migrated to another CPU. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1236709131.25234.576.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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1 changed files with 23 additions and 1 deletions
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@ -4620,6 +4620,28 @@ static inline void schedule_debug(struct task_struct *prev)
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#endif
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}
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static void put_prev_task(struct rq *rq, struct task_struct *prev)
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{
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if (prev->state == TASK_RUNNING) {
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u64 runtime = prev->se.sum_exec_runtime;
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runtime -= prev->se.prev_sum_exec_runtime;
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runtime = min_t(u64, runtime, 2*sysctl_sched_migration_cost);
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/*
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* In order to avoid avg_overlap growing stale when we are
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* indeed overlapping and hence not getting put to sleep, grow
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* the avg_overlap on preemption.
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*
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* We use the average preemption runtime because that
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* correlates to the amount of cache footprint a task can
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* build up.
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*/
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update_avg(&prev->se.avg_overlap, runtime);
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}
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prev->sched_class->put_prev_task(rq, prev);
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}
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/*
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* Pick up the highest-prio task:
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*/
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@ -4698,7 +4720,7 @@ asmlinkage void __sched schedule(void)
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if (unlikely(!rq->nr_running))
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idle_balance(cpu, rq);
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prev->sched_class->put_prev_task(rq, prev);
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put_prev_task(rq, prev);
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next = pick_next_task(rq);
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if (likely(prev != next)) {
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