[tip:sched/core] sched/fair: Fix comment in calculate_imbalance()

From: tip-bot for Dietmar Eggemann
Date: Thu May 05 2016 - 05:43:39 EST

Commit-ID: 885e542ce827f5f102fe9628d63c6430c8b7ab2c
Gitweb: http://git.kernel.org/tip/885e542ce827f5f102fe9628d63c6430c8b7ab2c
Author: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
AuthorDate: Fri, 29 Apr 2016 20:32:39 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Morten Rasmussen <morten.rasmussen@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1461958364-675-3-git-send-email-dietmar.eggemann@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
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) {