linux-kernel - [tip:sched/core] sched/fair: Fix comment in calculate

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Date:	Thu, 5 May 2016 02:42:55 -0700
From:	tip-bot for Dietmar Eggemann <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	dietmar.eggemann@....com, linux-kernel@...r.kernel.org,
	morten.rasmussen@....com, torvalds@...ux-foundation.org,
	hpa@...or.com, tglx@...utronix.de, peterz@...radead.org,
	efault@....de, mingo@...nel.org
Subject: [tip:sched/core] sched/fair: Fix comment in calculate_imbalance()

Commit-ID:  885e542ce827f5f102fe9628d63c6430c8b7ab2c
Gitweb:     http://git.kernel.org/tip/885e542ce827f5f102fe9628d63c6430c8b7ab2c
Author:     Dietmar Eggemann <dietmar.eggemann@....com>
AuthorDate: Fri, 29 Apr 2016 20:32:39 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 5 May 2016 09:41:10 +0200

sched/fair: Fix comment in calculate_imbalance()

The comment in calculate_imbalance() was introduced in commit:

 2dd73a4f09be ("[PATCH] sched: implement smpnice")

which described the logic as it was then, but a later commit:

  b18855500fc4 ("sched/balancing: Fix 'local->avg_load > sds->avg_load' case in calculate_imbalance()")

.. complicated this logic some more so that the comment does not match anymore.

Update the comment to match the code.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Morten Rasmussen <morten.rasmussen@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1461958364-675-3-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 537d71e..51f7a4b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7000,9 +7000,10 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
 	}
 
 	/*
-	 * In the presence of smp nice balancing, certain scenarios can have
-	 * max load less than avg load(as we skip the groups at or below
-	 * its cpu_capacity, while calculating max_load..)
+	 * Avg load of busiest sg can be less and avg load of local sg can
+	 * be greater than avg load across all sgs of sd because avg load
+	 * factors in sg capacity and sgs with smaller group_type are
+	 * skipped when updating the busiest sg:
 	 */
 	if (busiest->avg_load <= sds->avg_load ||
 	    local->avg_load >= sds->avg_load) {