sched/fair: Simplify wake_affine() for the single socket case (7d894e6e) · Commits · 戴 / test

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:

Rik 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:

Ingo Molnar <mingo@kernel.org>

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);

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