From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933942AbaEMOXi (ORCPT ); Tue, 13 May 2014 10:23:38 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:39588 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932891AbaEMOXh (ORCPT ); Tue, 13 May 2014 10:23:37 -0400 Date: Tue, 13 May 2014 16:23:28 +0200 From: Peter Zijlstra To: Rik van Riel Cc: Michael wang , LKML , Ingo Molnar , Mike Galbraith , Alex Shi , Paul Turner , Mel Gorman , Daniel Lezcano Subject: Re: [ISSUE] sched/cgroup: Does cpu-cgroup still works fine nowadays? Message-ID: <20140513142328.GE2485@laptop.programming.kicks-ass.net> References: <537192D3.5030907@linux.vnet.ibm.com> <20140513094737.GU30445@twins.programming.kicks-ass.net> <53721FD4.6060300@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53721FD4.6060300@redhat.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 13, 2014 at 09:36:20AM -0400, Rik van Riel wrote: > On 05/13/2014 05:47 AM, Peter Zijlstra wrote: > > On Tue, May 13, 2014 at 11:34:43AM +0800, Michael wang wrote: > >> During our testing, we found that the cpu.shares doesn't work as > >> expected, the testing is: > >> > > > > /me zaps all the kvm nonsense as that's non reproducable and only serves > > to annoy. > > > > Pro-tip: never use kvm to report cpu-cgroup issues. > > > >> So is this results expected (I really do not think so...)? > >> > >> Or that imply the cpu-cgroup got some issue to be fixed? > > > > So what I did (WSM-EP 2x6x2): > > > > mount none /cgroup -t cgroup -o cpu > > mkdir -p /cgroup/a > > mkdir -p /cgroup/b > > mkdir -p /cgroup/c > > > > echo $$ > /cgroup/a/tasks ; for ((i=0; i<12; i++)) ; do A.sh & done > > echo $$ > /cgroup/b/tasks ; for ((i=0; i<12; i++)) ; do B.sh & done > > echo $$ > /cgroup/c/tasks ; for ((i=0; i<12; i++)) ; do C.sh & done > > > > echo 2048 > /cgroup/c/cpu.shares > > > > Where [ABC].sh are spinners: > > I suspect the "are spinners" is key. > > Infinite loops can run all the time, while dbench spends a lot of > its time waiting for locks. That waiting may interfere with getting > as much CPU as it wants. At which point it becomes an entirely different problem and the weight things become far more 'interesting'. The point remains though, don't use massive and awkward software stacks that are impossible to operate. I you want to investigate !spinners, replace the ABC with slightly more complex loads like: https://lkml.org/lkml/2012/6/18/212