From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964970AbWBANMq (ORCPT ); Wed, 1 Feb 2006 08:12:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964960AbWBANMq (ORCPT ); Wed, 1 Feb 2006 08:12:46 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:29854 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S964958AbWBANMp (ORCPT ); Wed, 1 Feb 2006 08:12:45 -0500 Date: Wed, 1 Feb 2006 14:11:11 +0100 From: Ingo Molnar To: Steven Rostedt Cc: Thomas Gleixner , Andrew Morton , LKML Subject: Re: [PATCH] Avoid moving tasks when a schedule can be made. Message-ID: <20060201131111.GA27793@elte.hu> References: <1138736609.7088.35.camel@localhost.localdomain> <20060201130818.GA26481@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060201130818.GA26481@elte.hu> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar wrote: > i think the right approach would be to split up this work into smaller > chunks. Or rather, lets first see how this can happen: why is > can_migrate() false for so many tasks? Are they all cpu-hot? If yes, > shouldnt we simply skip only up to a limit of tasks in this case - > it's not like we want to spend 1.5 msecs searching for a cache-cold > task which might give us a 50 usecs advantage over cache-hot tasks ... the only legimate case where we have to skip alot of tasks is the case when there are alot of CPU-bound (->cpus_alowed) tasks in the runqueue. In that case the scheduler really has to skip that task. But that is not an issue in your workload. Ingo