Commit 111688ca authored Mar 26, 2020 by Aubrey Li Committed by Ingo Molnar Apr 08, 2020

sched/fair: Fix negative imbalance in imbalance calculation



A negative imbalance value was observed after imbalance calculation,
this happens when the local sched group type is group_fully_busy,
and the average load of local group is greater than the selected
busiest group. Fix this problem by comparing the average load of the
local and busiest group before imbalance calculation formula.

Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/1585201349-70192-1-git-send-email-aubrey.li@intel.com

parent 26a8b127

kernel/sched/fair.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -9036,6 +9036,14 @@ static inline void calculate_imbalance(struct lb_env env, struct sd_lb_stats s

		sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
		sds->total_capacity;
		/*
		* If the local group is more loaded than the selected
		* busiest group don't try to pull any tasks.
		*/
		if (local->avg_load >= busiest->avg_load) {
		env->imbalance = 0;
		return;
		}
		}

		/*

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