From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753982Ab3BRNCM (ORCPT ); Mon, 18 Feb 2013 08:02:12 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:42093 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753522Ab3BRNCI (ORCPT ); Mon, 18 Feb 2013 08:02:08 -0500 Date: Mon, 18 Feb 2013 18:31:46 +0530 From: Srikar Dronamraju To: Ingo Molnar , Peter Zijlstra , LKML Cc: Mike Galbraith Subject: [PATCH] sched: Skip looking at skip if next or last is set Message-ID: <20130218130146.GA7472@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021813-5806-0000-0000-00001FC693B8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pick_next_entity() prefers next, then last. However code checks if the left entity can be skipped even if next / last is set. Check if left entity should be skipped only if next/last is not set. Signed-off-by: Srikar Dronamraju --- kernel/sched/fair.c | 31 +++++++++++++++---------------- 1 files changed, 15 insertions(+), 16 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index fdee793..cc97b12 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1900,27 +1900,26 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) struct sched_entity *left = se; /* - * Avoid running the skip buddy, if running something else can - * be done without getting too unfair. + * Someone really wants next to run. If it's not unfair, run it. */ - if (cfs_rq->skip == se) { - struct sched_entity *second = __pick_next_entity(se); + if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) { + se = cfs_rq->next; + } else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) { + /* + * Prefer last buddy, try to return the CPU to a preempted + * task. + */ + se = cfs_rq->last; + } else if (cfs_rq->skip == left) { + /* + * Avoid running the skip buddy, if running something else + * can be done without getting too unfair. + */ + struct sched_entity *second = __pick_next_entity(left); if (second && wakeup_preempt_entity(second, left) < 1) se = second; } - /* - * Prefer last buddy, try to return the CPU to a preempted task. - */ - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) - se = cfs_rq->last; - - /* - * Someone really wants this to run. If it's not unfair, run it. - */ - if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) - se = cfs_rq->next; - clear_buddies(cfs_rq, se); return se;