From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758068Ab1KRPXb (ORCPT ); Fri, 18 Nov 2011 10:23:31 -0500 Received: from mailout-de.gmx.net ([213.165.64.23]:48549 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757856Ab1KRPXa (ORCPT ); Fri, 18 Nov 2011 10:23:30 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX195WDodD4956P88GGZjcCTagpu5tShB7h+ZXtGKi6 7jbpLn1piQo3w5 Subject: [patch 6/6] sched: set skip_clock_update in yield_task_fair() From: Mike Galbraith To: Suresh Siddha Cc: Peter Zijlstra , linux-kernel , Ingo Molnar , Paul Turner In-Reply-To: <1321629267.7080.13.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> Content-Type: text/plain; charset="UTF-8" Date: Fri, 18 Nov 2011 16:23:26 +0100 Message-ID: <1321629806.7080.23.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 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.c | 8 +++++++- kernel/sched_fair.c | 6 ++++++ 2 files changed, 13 insertions(+), 1 deletion(-) Index: linux-3.2.git/kernel/sched.c =================================================================== --- linux-3.2.git.orig/kernel/sched.c +++ linux-3.2.git/kernel/sched.c @@ -5838,7 +5838,13 @@ 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-3.2.git/kernel/sched_fair.c =================================================================== --- linux-3.2.git.orig/kernel/sched_fair.c +++ linux-3.2.git/kernel/sched_fair.c @@ -2688,6 +2688,12 @@ 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);