linux-kernel - [PATCH 2/7] sched/fair: Fix comment in calculate

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Date:	Fri, 29 Apr 2016 20:32:39 +0100
From:	Dietmar Eggemann <dietmar.eggemann@....com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org,
	Morten Rasmussen <morten.rasmussen@....com>
Subject: [PATCH 2/7] sched/fair: Fix comment in calculate_imbalance()

The comment survived from commit 2dd73a4f09be ("[PATCH] sched:
implement smpnice") in which the selection of busiest and
busiest->avg_load (max_load) was based on if(avg_load > max_load
&& sum_nr_running > group->cpu_power / SCHED_LOAD_SCALE).

Commit b18855500fc4 ("sched/balancing: Fix 'local->avg_load >
sds->avg_load' case in calculate_imbalance()") added the second
operand of the or operator.

Update this comment accordingly and also use the current variable
names.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 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 c77e01b55ec2..bc19fee94f39 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6998,9 +6998,10 @@ 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) {
-- 
1.9.1