Commit a731ebe6 authored Sep 06, 2017 by Peter Zijlstra Committed by Ingo Molnar Sep 07, 2017

sched/fair: Fix wake_affine_llc() balancing rules



Chris Wilson reported that the SMT balance rules got the +1 on the
wrong side, resulting in a bias towards the current LLC; which the
load-balancer would then try and undo.

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 90001d67 ("sched/fair: Fix wake_affine() for !NUMA_BALANCING")
Link: http://lkml.kernel.org/r/20170906105131.gqjmaextmn3u6tj2@hirez.programming.kicks-ass.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 24e700e2

kernel/sched/fair.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5435,7 +5435,7 @@ wake_affine_llc(struct sched_domain sd, struct task_struct p,
		return false;

		/* if this cache has capacity, come here */
		if (this_stats.has_capacity && this_stats.nr_running < prev_stats.nr_running+1)
		if (this_stats.has_capacity && this_stats.nr_running+1 < prev_stats.nr_running)
		return true;

		/*

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