Commit-ID: 66856ff8e727e7da7da44a634f314b236510f419 Gitweb: https://git.kernel.org/tip/66856ff8e727e7da7da44a634f314b236510f419 Author: Valentin Schneider <[email protected]> AuthorDate: Mon, 11 Feb 2019 17:59:44 +0000 Committer: Ingo Molnar <[email protected]> CommitDate: Sat, 9 Mar 2019 14:03:52 +0100
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 <[email protected]> Signed-off-by: Valentin Schneider <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: [email protected] Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/fair.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8213ff6e365d..e6f7d39d4d45 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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;
