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sched/nohz: Optimize nohz_idle_balance() 

Avoid calling update_blocked_averages() when it does not in fact have
any by re-using/extending update_nohz_stats().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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 2018-02-13 16:54:17 +01:00 committed by Ingo Molnar
parent 1936c53ce8
commit 63928384fa
1 changed files with 4 additions and 5 deletions
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9
kernel/sched/fair.c
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@ -7898,7 +7898,7 @@ group_type group_classify(struct sched_group *group,
return group_other;
}
static bool update_nohz_stats(struct rq *rq)
static bool update_nohz_stats(struct rq *rq, bool force)
{
#ifdef CONFIG_NO_HZ_COMMON
unsigned int cpu = rq->cpu;
@ -7909,7 +7909,7 @@ static bool update_nohz_stats(struct rq *rq)
if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
return false;
if (!time_after(jiffies, rq->last_blocked_load_update_tick))
if (!force && !time_after(jiffies, rq->last_blocked_load_update_tick))
return true;
update_blocked_averages(cpu);
@ -7942,7 +7942,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
for_each_cpu_and(i, sched_group_span(group), env->cpus) {
struct rq *rq = cpu_rq(i);
if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq))
if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq, false))
env->flags |= LBF_NOHZ_AGAIN;
/* Bias balancing toward CPUs of our domain: */
@ -9552,8 +9552,7 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
rq = cpu_rq(balance_cpu);
update_blocked_averages(rq->cpu);
has_blocked_load |= rq->has_blocked_load;
has_blocked_load |= update_nohz_stats(rq, true);
/*
* If time for next balance is due,