From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754838AbaF3Irc (ORCPT ); Mon, 30 Jun 2014 04:47:32 -0400 Received: from e23smtp05.au.ibm.com ([202.81.31.147]:60440 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752527AbaF3Ira (ORCPT ); Mon, 30 Jun 2014 04:47:30 -0400 Message-ID: <53B12417.9060904@linux.vnet.ibm.com> Date: Mon, 30 Jun 2014 16:47:19 +0800 From: Michael wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Mike Galbraith CC: Peter Zijlstra , Rik van Riel , Ingo Molnar , Alex Shi , Paul Turner , Mel Gorman , Daniel Lezcano , LKML Subject: Re: [PATCH] sched: select 'idle' cfs_rq per task-group to prevent tg-internal imbalance References: <53A11A89.5000602@linux.vnet.ibm.com> <53B11387.9020001@linux.vnet.ibm.com> <1404115601.5132.156.camel@marge.simpson.net> In-Reply-To: <1404115601.5132.156.camel@marge.simpson.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14063008-1396-0000-0000-000005225889 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Mike :) On 06/30/2014 04:06 PM, Mike Galbraith wrote: > 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' :) I'm new to this word... could you give more details on that? > > 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. The preemtion based on vruntime sounds fair enough, but vruntime-bonus for wakee do need few more thinking... although I don't want to count the gentle-stuff in any more, but disable it do help dbench a lot... Regards, Michael Wang > > -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/ >