From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756272Ab1KVO3S (ORCPT ); Tue, 22 Nov 2011 09:29:18 -0500 Received: from cantor2.suse.de ([195.135.220.15]:42437 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756233Ab1KVO3P (ORCPT ); Tue, 22 Nov 2011 09:29:15 -0500 Subject: [patch 3/7] sched: set skip_clock_update in yield_task_fair() From: Mike Galbraith To: Peter Zijlstra Cc: Suresh Siddha , linux-kernel , Ingo Molnar , Paul Turner In-Reply-To: <1321971445.6855.14.camel@marge.simson.net> References: <1321350377.1421.55.camel@twins> <1321406062.16760.60.camel@sbsiddha-desk.sc.intel.com> <1321435455.5072.64.camel@marge.simson.net> <1321468646.11680.2.camel@sbsiddha-desk.sc.intel.com> <1321495153.5100.7.camel@marge.simson.net> <1321544313.6308.25.camel@marge.simson.net> <1321545376.2495.1.camel@laptop> <1321547917.6308.48.camel@marge.simson.net> <1321551381.15339.21.camel@sbsiddha-desk.sc.intel.com> <1321629267.7080.13.camel@marge.simson.net> <1321629441.7080.15.camel@marge.simson.net> <1321630552.2197.15.camel@twins> <1321971445.6855.14.camel@marge.simson.net> Content-Type: text/plain; charset="UTF-8" Date: Tue, 22 Nov 2011 15:21:26 +0100 Message-ID: <1321971686.6855.18.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is another case where we are on our way to schedule(), so can save a useless clock update and resulting microscopic vruntime update. Signed-off-by: Mike Galbraith --- kernel/sched/core.c | 8 +++++++- kernel/sched/fair.c | 6 ++++++ 2 files changed, 13 insertions(+), 1 deletion(-) Index: linux-3.0-tip/kernel/sched/core.c =================================================================== --- linux-3.0-tip.orig/kernel/sched/core.c +++ linux-3.0-tip/kernel/sched/core.c @@ -4547,7 +4547,13 @@ again: */ if (preempt && rq != p_rq) resched_task(p_rq->curr); - } + } else + /* + * We might have set it in task_yield_fair(), but are + * not going to schedule(), so don't want to skip + * the next update. + */ + rq->skip_clock_update = 0; out: double_rq_unlock(rq, p_rq); Index: linux-3.0-tip/kernel/sched/fair.c =================================================================== --- linux-3.0-tip.orig/kernel/sched/fair.c +++ linux-3.0-tip/kernel/sched/fair.c @@ -3062,6 +3062,12 @@ static void yield_task_fair(struct rq *r * Update run-time statistics of the 'current'. */ update_curr(cfs_rq); + /* + * Tell update_rq_clock() that we've just updated, + * so we don't do microscopic update in schedule() + * and double the fastpath cost. + */ + rq->skip_clock_update = 1; } set_skip_buddy(se);