From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752581AbcHJSEv (ORCPT ); Wed, 10 Aug 2016 14:04:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56058 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932638AbcHJSEd (ORCPT ); Wed, 10 Aug 2016 14:04:33 -0400 Date: Wed, 10 Aug 2016 11:03:57 -0700 From: tip-bot for Morten Rasmussen Message-ID: Cc: tglx@linutronix.de, hpa@zytor.com, efault@gmx.de, torvalds@linux-foundation.org, peterz@infradead.org, morten.rasmussen@arm.com, mingo@kernel.org, linux-kernel@vger.kernel.org Reply-To: efault@gmx.de, hpa@zytor.com, tglx@linutronix.de, peterz@infradead.org, morten.rasmussen@arm.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org In-Reply-To: <1466615004-3503-4-git-send-email-morten.rasmussen@arm.com> References: <1466615004-3503-4-git-send-email-morten.rasmussen@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/fair: Optimize find_idlest_cpu() when there is no choice Git-Commit-ID: eaecf41f5abf80b63c8e025fcb9ee4aa203c3038 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: eaecf41f5abf80b63c8e025fcb9ee4aa203c3038 Gitweb: http://git.kernel.org/tip/eaecf41f5abf80b63c8e025fcb9ee4aa203c3038 Author: Morten Rasmussen AuthorDate: Wed, 22 Jun 2016 18:03:14 +0100 Committer: Ingo Molnar CommitDate: Wed, 10 Aug 2016 14:03:32 +0200 sched/fair: Optimize find_idlest_cpu() when there is no choice In the current find_idlest_group()/find_idlest_cpu() search we end up calling find_idlest_cpu() in a sched_group containing only one CPU in the end. Checking idle-states becomes pointless when there is no alternative, so bail out instead. Signed-off-by: Morten Rasmussen Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dietmar.eggemann@arm.com Cc: linux-kernel@vger.kernel.org Cc: mgalbraith@suse.de Cc: vincent.guittot@linaro.org Cc: yuyang.du@intel.com Link: http://lkml.kernel.org/r/1466615004-3503-4-git-send-email-morten.rasmussen@arm.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d819da6..acdc351 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5239,6 +5239,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) int shallowest_idle_cpu = -1; int i; + /* Check if we have any choice: */ + if (group->group_weight == 1) + return cpumask_first(sched_group_cpus(group)); + /* Traverse only the allowed CPUs */ for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { if (idle_cpu(i)) {