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Commit 7d894e6e authored by Rik van Riel's avatar Rik van Riel Committed by Ingo Molnar
Browse files

sched/fair: Simplify wake_affine() for the single socket case 



Then 'this_cpu' and 'prev_cpu' are in the same socket, select_idle_sibling()
will do its thing regardless of the return value of wake_affine().

Just return true and don't look at all the other things.

Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jhladky@redhat.com
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20170623165530.22514-3-riel@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 739294fb

kernel/sched/fair.c

+12 −1
Original line number Diff line number Diff line
@@ -5419,6 +5419,13 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, 
	load	  = source_load(prev_cpu, idx);

	this_load = target_load(this_cpu, idx);



	/*

	 * Common case: CPUs are in the same socket, and select_idle_sibling()

	 * will do its thing regardless of what we return:

	 */

	if (cpus_share_cache(prev_cpu, this_cpu))

		return true;



	/*

	 * If sync wakeup then subtract the (maximum possible)

	 * effect of the currently running task from the load
@@ -6007,11 +6014,15 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 


	if (affine_sd) {

		sd = NULL; /* Prefer wake_affine over balance flags */

		if (cpu != prev_cpu && wake_affine(affine_sd, p, prev_cpu, sync))

		if (cpu == prev_cpu)

			goto pick_cpu;



		if (wake_affine(affine_sd, p, prev_cpu, sync))

			new_cpu = cpu;

	}



	if (!sd) {

 pick_cpu:

		if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */

			new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);