Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754772AbaF3IGu (ORCPT ); Mon, 30 Jun 2014 04:06:50 -0400 Received: from mail-we0-f169.google.com ([74.125.82.169]:52882 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752182AbaF3IGp (ORCPT ); Mon, 30 Jun 2014 04:06:45 -0400 Message-ID: <1404115601.5132.156.camel@marge.simpson.net> Subject: Re: [PATCH] sched: select 'idle' cfs_rq per task-group to prevent tg-internal imbalance From: Mike Galbraith To: Michael wang Cc: Peter Zijlstra , Rik van Riel , Ingo Molnar , Alex Shi , Paul Turner , Mel Gorman , Daniel Lezcano , LKML Date: Mon, 30 Jun 2014 10:06:41 +0200 In-Reply-To: <53B11387.9020001@linux.vnet.ibm.com> References: <53A11A89.5000602@linux.vnet.ibm.com> <53B11387.9020001@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-06-30 at 15:36 +0800, Michael wang wrote: > On 06/18/2014 12:50 PM, Michael wang wrote: > > By testing we found that after put benchmark (dbench) in to deep cpu-group, > > tasks (dbench routines) start to gathered on one CPU, which lead to that the > > benchmark could only get around 100% CPU whatever how big it's task-group's > > share is, here is the link of the way to reproduce the issue: > > Hi, Peter > > We thought that involved too much factors will make things too > complicated, we are trying to start over and get rid of the concepts of > 'deep-group' and 'GENTLE_FAIR_SLEEPERS' in the idea, wish this could > make things more easier... While you're getting rid of the concept of 'GENTLE_FAIR_SLEEPERS', don't forget to also get rid of the concept of 'over-scheduling' :) That gentle thing isn't perfect (is the enemy of good), but preemption model being based upon sleep, while nice and simple, has the unfortunate weakness that as contention increases, so does the quantity of sleep in the system. Would be nice to come up with an alternative preemption model as dirt simple as this one, but lacking the inherent weakness. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/