From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932418Ab3BMSnQ (ORCPT ); Wed, 13 Feb 2013 13:43:16 -0500 Received: from merlin.infradead.org ([205.233.59.134]:39567 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754236Ab3BMSnP (ORCPT ); Wed, 13 Feb 2013 13:43:15 -0500 Message-ID: <1360780981.8957.3.camel@laptop> Subject: Re: [PATCH 2/3] sched: Move idle_balance() to post_schedule From: Peter Zijlstra To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Vincent Guittot , Frederic Weisbecker , Mike Galbraith Date: Wed, 13 Feb 2013 19:43:01 +0100 In-Reply-To: <20130212230017.625583020@goodmis.org> References: <20130212225412.781044738@goodmis.org> <20130212230017.625583020@goodmis.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2013-02-12 at 17:54 -0500, Steven Rostedt wrote: > There's no real reason that the idle_balance() needs to be called in > the > middle of schedule anyway. The only benefit is that if a task is > pulled > to this CPU, it can be scheduled without the need to schedule the idle > task. Uhm, istr that extra schedule being an issue somewhere.. Make very sure you don't regress anything silly like sysbench or hackbench. Maybe ask Mike, he seems to have a better retention for benchmark weirdness than me. > But load balancing and migrating the task makes a switch to idle > and back negligible. How does that follow? We can have to-idle switches _far_ more often than we balance.