lkml.org 
[lkml]   [2019]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:sched/urgent] sched/fair: Comment some nohz_balancer_kick() kick conditions
Commit-ID:  66856ff8e727e7da7da44a634f314b236510f419
Gitweb: https://git.kernel.org/tip/66856ff8e727e7da7da44a634f314b236510f419
Author: Valentin Schneider <valentin.schneider@arm.com>
AuthorDate: Mon, 11 Feb 2019 17:59:44 +0000
Committer: Ingo Molnar <mingo@kernel.org>
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 <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>
---
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;
\
 
 \ /
  Last update: 2019-03-09 15:38    [W:0.074 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site