From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753459Ab0HZSPw (ORCPT ); Thu, 26 Aug 2010 14:15:52 -0400 Received: from smtp.polymtl.ca ([132.207.4.11]:55259 "EHLO smtp.polymtl.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753148Ab0HZSOt (ORCPT ); Thu, 26 Aug 2010 14:14:49 -0400 Message-Id: <20100826181340.580313949@efficios.com> User-Agent: quilt/0.48-1 Date: Thu, 26 Aug 2010 14:09:13 -0400 From: Mathieu Desnoyers To: LKML , Peter Zijlstra Cc: Linus Torvalds , Andrew Morton , Ingo Molnar , Steven Rostedt , Thomas Gleixner , Mathieu Desnoyers , Tony Lindgren , Mike Galbraith , Peter Zijlstra Subject: [RFC PATCH 05/11] sched buddy enable buddy logic starting at 2 running threads References: <20100826180908.648103531@efficios.com> Content-Disposition: inline; filename=sched-buddy-enable-at-2.patch X-Poly-FromMTA: (test.casi.polymtl.ca [132.207.72.60]) at Thu, 26 Aug 2010 18:13:40 +0000 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Extracted from a "sched-misc-bits.patch" patch from Peter Zijlstra . Signed-off-by: Mathieu Desnoyers CC: Peter Zijlstra --- kernel/sched_fair.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) Index: linux-2.6-lttng.git/kernel/sched_fair.c =================================================================== --- linux-2.6-lttng.git.orig/kernel/sched_fair.c +++ linux-2.6-lttng.git/kernel/sched_fair.c @@ -1647,7 +1647,11 @@ static void check_preempt_wakeup(struct struct task_struct *curr = rq->curr; struct sched_entity *se = &curr->se, *pse = &p->se; struct cfs_rq *cfs_rq = task_cfs_rq(curr); - int scale = cfs_rq->nr_running >= sched_nr_latency; + /* + * The buddy logic doesn't work well when there's not actually enough + * tasks for there to be buddies. + */ + int buddies = (cfs_rq->nr_running >= 2); if (unlikely(rt_prio(p->prio))) goto preempt; @@ -1658,7 +1662,7 @@ static void check_preempt_wakeup(struct if (unlikely(se == pse)) return; - if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) + if (sched_feat(NEXT_BUDDY) && buddies && !(wake_flags & WF_FORK)) set_next_buddy(pse); /* @@ -1704,7 +1708,7 @@ preempt: if (unlikely(!se->on_rq || curr == rq->idle)) return; - if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) + if (sched_feat(LAST_BUDDY) && buddies && entity_is_task(se)) set_last_buddy(se); }