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sched/core: Optimize ttwu_stat()

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The whole of ttwu_stat() is guarded by a single schedstat_enabled(),
there is absolutely no point in then issuing another static_branch for
every single schedstat_inc() in there.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2018-01-16 20:51:06 +01:00 committed by Ingo Molnar
parent 460e8c3340
commit b85c8b71bf
2 changed files with 10 additions and 8 deletions
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16
kernel/sched/core.c
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@ -1630,16 +1630,16 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
#ifdef CONFIG_SMP
if (cpu == rq->cpu) {
schedstat_inc(rq->ttwu_local);
schedstat_inc(p->se.statistics.nr_wakeups_local);
__schedstat_inc(rq->ttwu_local);
__schedstat_inc(p->se.statistics.nr_wakeups_local);
} else {
struct sched_domain *sd;
schedstat_inc(p->se.statistics.nr_wakeups_remote);
__schedstat_inc(p->se.statistics.nr_wakeups_remote);
rcu_read_lock();
for_each_domain(rq->cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
schedstat_inc(sd->ttwu_wake_remote);
__schedstat_inc(sd->ttwu_wake_remote);
break;
}
}
@ -1647,14 +1647,14 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
}
if (wake_flags & WF_MIGRATED)
schedstat_inc(p->se.statistics.nr_wakeups_migrate);
__schedstat_inc(p->se.statistics.nr_wakeups_migrate);
#endif /* CONFIG_SMP */
schedstat_inc(rq->ttwu_count);
schedstat_inc(p->se.statistics.nr_wakeups);
__schedstat_inc(rq->ttwu_count);
__schedstat_inc(p->se.statistics.nr_wakeups);
if (wake_flags & WF_SYNC)
schedstat_inc(p->se.statistics.nr_wakeups_sync);
__schedstat_inc(p->se.statistics.nr_wakeups_sync);
}
static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)

2
kernel/sched/stats.h
View File

@ -31,6 +31,7 @@ rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
rq->rq_sched_info.run_delay += delta;
}
#define schedstat_enabled() static_branch_unlikely(&sched_schedstats)
#define __schedstat_inc(var) do { var++; } while (0)
#define schedstat_inc(var) do { if (schedstat_enabled()) { var++; } } while (0)
#define schedstat_add(var, amt) do { if (schedstat_enabled()) { var += (amt); } } while (0)
#define schedstat_set(var, val) do { if (schedstat_enabled()) { var = (val); } } while (0)
@ -48,6 +49,7 @@ static inline void
rq_sched_info_depart(struct rq *rq, unsigned long long delta)
{}
#define schedstat_enabled() 0
#define __schedstat_inc(var) do { } while (0)
#define schedstat_inc(var) do { } while (0)
#define schedstat_add(var, amt) do { } while (0)
#define schedstat_set(var, val) do { } while (0)