sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block

The comment block for that function lists the heuristics for
triggering a nohz kick, but the most recent ones (blocked load
updates, misfit) aren't included, and some of them (LLC nohz logic,
asym packing) are no longer in sync with the code.

The conditions are either simple enough or properly commented, so get
rid of that list instead of letting it grow.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190117153411.2390-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ac6b52d8c79e72596eb5eaab4f1b4623bf96e31f..f44da9b491ffcdd7197eb4a9b1b851b388b2652b 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9551,15 +9551,8 @@ static void kick_ilb(unsigned int flags)
 }
 
 /*
- * Current heuristic for kicking the idle load balancer in the presence
- * of an idle cpu in the system.
- *   - This rq has more than one task.
- *   - This rq has at least one CFS task and the capacity of the CPU is
- *     significantly reduced because of RT tasks or IRQs.
- *   - At parent of LLC scheduler domain level, this cpu's scheduler group has
- *     multiple busy cpu.
- *   - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
- *     domain span are idle.
+ * Current decision point for kicking the idle load balancer in the presence
+ * of idle CPUs in the system.
  */
 static void nohz_balancer_kick(struct rq *rq)
 {