Commit e25a7a94 authored Feb 11, 2019 by Valentin Schneider Committed by Ingo Molnar Mar 19, 2019

sched/fair: Comment some nohz_balancer_kick() kick conditions



We now have a comment explaining the first sched_domain based NOHZ kick,
so might as well comment them all.

While at it, unwrap a line that fits under 80 characters.

Co-authored-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-2-valentin.schneider@arm.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 4c47acd8

kernel/sched/fair.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -9612,8 +9612,12 @@ static void nohz_balancer_kick(struct rq *rq)

		sd = rcu_dereference(rq->sd);
		if (sd) {
		if ((rq->cfs.h_nr_running >= 1) &&
		check_cpu_capacity(rq, sd)) {
		/*
		* If there's a CFS task and the current CPU has reduced
		* capacity; kick the ILB to see if there's a better CPU to run
		* on.
		*/
		if (rq->cfs.h_nr_running >= 1 && check_cpu_capacity(rq, sd)) {
		flags = NOHZ_KICK_MASK;
		goto unlock;
		}
		@@ -9621,6 +9625,11 @@ static void nohz_balancer_kick(struct rq *rq)

		sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
		if (sd) {
		/*
		* When ASYM_PACKING; see if there's a more preferred CPU
		* currently idle; in which case, kick the ILB to move tasks
		* around.
		*/
		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
		if (sched_asym_prefer(i, cpu)) {
		flags = NOHZ_KICK_MASK;