From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753408AbZIRTvm (ORCPT ); Fri, 18 Sep 2009 15:51:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752606AbZIRTvh (ORCPT ); Fri, 18 Sep 2009 15:51:37 -0400 Received: from tx2ehsobe003.messaging.microsoft.com ([65.55.88.13]:47850 "EHLO TX2EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752529AbZIRTvg (ORCPT ); Fri, 18 Sep 2009 15:51:36 -0400 X-SpamScore: 10 X-BigFish: VPS10(z5c5ozzz1202hzzz32i203h6bh43j61h) X-Spam-TCS-SCL: 0:0 X-FB-SS: 5, X-WSS-ID: 0KQ6N5O-02-BNT-02 X-M-MSG: From: Mark Langsdorf To: linux-kernel@vger.kernel.org Subject: [PATCH] Prevent immediate process rescheduling Date: Fri, 18 Sep 2009 14:49:12 -0500 User-Agent: KMail/1.9.10 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-ID: <200909181449.12311.mark.langsdorf@amd.com> X-OriginalArrivalTime: 18 Sep 2009 19:51:28.0549 (UTC) FILETIME=[698D2550:01CA3899] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Prevent the scheduler from immediately rescheduling a process that just yielded if there is another process available. Originally suggested by Mike Galbraith (efault@gmx.de). Signed-off-by: Mark Langsdorf --- kernel/sched_fair.c | 16 +++++++++++++++- 1 files changed, 15 insertions(+), 1 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 652e8bd..4fad08f 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -353,11 +353,25 @@ static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) { struct rb_node *left = cfs_rq->rb_leftmost; + struct sched_entity *se, *curr; if (!left) return NULL; - return rb_entry(left, struct sched_entity, run_node); + se = rb_entry(left, struct sched_entity, run_node); + curr = ¤t->se; + + /* + * Don't select the entity who just tried to schedule away + * if there's another entity available. + */ + if (unlikely(se == curr && cfs_rq->nr_running > 1)) { + struct rb_node *next_node = rb_next(&curr->run_node); + if (next_node) + se = rb_entry(next_node, struct sched_entity, run_node); + } + + return se; } static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) -- 1.6.0.2