sched: stop wake_affine from causing serious imbalance
Prevent short-running wakers of short-running threads from overloading a single cpu via wakeup affinity, and wire up disconnected debug option. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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1 changed files with 19 additions and 16 deletions
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@ -996,24 +996,11 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
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struct task_struct *curr = this_rq->curr;
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unsigned long tl = this_load;
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unsigned long tl_per_task;
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int balanced;
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if (!(this_sd->flags & SD_WAKE_AFFINE))
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if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
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return 0;
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/*
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* If the currently running task will sleep within
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* a reasonable amount of time then attract this newly
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* woken task:
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*/
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if (sync && curr->sched_class == &fair_sched_class) {
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if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
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p->se.avg_overlap < sysctl_sched_migration_cost)
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return 1;
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}
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schedstat_inc(p, se.nr_wakeups_affine_attempts);
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tl_per_task = cpu_avg_load_per_task(this_cpu);
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/*
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* If sync wakeup then subtract the (maximum possible)
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* effect of the currently running task from the load
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@ -1022,8 +1009,24 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
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if (sync)
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tl -= current->se.load.weight;
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balanced = 100*(tl + p->se.load.weight) <= imbalance*load;
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/*
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* If the currently running task will sleep within
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* a reasonable amount of time then attract this newly
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* woken task:
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*/
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if (sync && balanced && curr->sched_class == &fair_sched_class) {
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if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
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p->se.avg_overlap < sysctl_sched_migration_cost)
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return 1;
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}
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schedstat_inc(p, se.nr_wakeups_affine_attempts);
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tl_per_task = cpu_avg_load_per_task(this_cpu);
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if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
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100*(tl + p->se.load.weight) <= imbalance*load) {
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balanced) {
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/*
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* This domain has SD_WAKE_AFFINE and
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* p is cache cold in this domain, and
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