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From: Valentin Schneider <valentin.schneider@arm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, peterz@infradead.org,
	vincent.guittot@linaro.org, morten.rasmussen@arm.com,
	Dietmar.Eggemann@arm.com
Subject: [PATCH 3/5] sched/fair: Prune nohz_balancer_kick() comment block
Date: Thu, 17 Jan 2019 15:34:09 +0000	[thread overview]
Message-ID: <20190117153411.2390-4-valentin.schneider@arm.com> (raw)
In-Reply-To: <20190117153411.2390-1-valentin.schneider@arm.com>

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>
---
 kernel/sched/fair.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 62f6aead7e73..7658f9d76a9a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9493,15 +9493,8 @@ 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)
 {
-- 
2.20.1


  parent reply	other threads:[~2019-01-17 15:37 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-17 15:34 [PATCH 0/5] sched/fair: NOHZ cleanups and misfit improvement Valentin Schneider
2019-01-17 15:34 ` [PATCH 1/5] sched/fair: Use for_each_cpu_and for asym-packing nohz kicks Valentin Schneider
2019-02-11 10:50   ` [tip:sched/core] sched/fair: Simplify nohz_balancer_kick() tip-bot for Valentin Schneider
2019-01-17 15:34 ` [PATCH 2/5] sched/fair: Explain LLC nohz kick condition Valentin Schneider
2019-02-11 10:51   ` [tip:sched/core] " tip-bot for Valentin Schneider
2019-01-17 15:34 ` Valentin Schneider [this message]
2019-02-11 10:51   ` [tip:sched/core] sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block tip-bot for Valentin Schneider
2019-01-17 15:34 ` [PATCH 4/5] sched/fair: Tune down misfit nohz kicks Valentin Schneider
2019-02-06 16:04   ` Peter Zijlstra
2019-02-06 17:25     ` Valentin Schneider
2019-02-07  9:57       ` Peter Zijlstra
2019-01-17 15:34 ` [PATCH 5/5] sched/fair: Skip LLC nohz logic for asymmetric systems Valentin Schneider
2019-02-06 16:14   ` Peter Zijlstra
2019-02-06 17:26     ` Valentin Schneider
2019-02-07  9:56       ` Peter Zijlstra
2019-02-07 11:31         ` Valentin Schneider
2019-02-06 14:33 ` [PATCH 0/5] sched/fair: NOHZ cleanups and misfit improvement Valentin Schneider

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