From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754765AbaANA6r (ORCPT ); Mon, 13 Jan 2014 19:58:47 -0500 Received: from blackpearl.yuhu.biz ([85.14.7.126]:37768 "EHLO BlackPearl.yuhu.biz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752680AbaANA6N (ORCPT ); Mon, 13 Jan 2014 19:58:13 -0500 Message-ID: <52D48BA6.2080701@yuhu.biz> Date: Tue, 14 Jan 2014 02:58:14 +0200 From: Marian Marinov User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Peter Zijlstra CC: lxc-devel@lists.linuxcontainers.org, cgroups@vger.kernel.org, "Daniel P. Berrange" , Serge Hallyn , Li Zefan , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: RFC: cgroups aware proc References: <52D35CD0.9070602@huawei.com> <52D41316.5080508@yuhu.biz> <20140113171238.GS31570@twins.programming.kicks-ass.net> In-Reply-To: <20140113171238.GS31570@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/13/2014 07:12 PM, Peter Zijlstra wrote: > On Mon, Jan 13, 2014 at 06:23:50PM +0200, Marian Marinov wrote: >> Hello Peter, >> >> I need help with the scheduler. >> >> I'm currently trying to patch the /proc/loadavg to show the load that is >> only related to the processes from the current cgroup. >> >> I looked trough the code and I was hoping that tsk->sched_task_group->cfs_rq >> struct will give me the needed information, but unfortunately for me, it did >> not. >> >> Can you advise me, how to approach this problem? > > Yeah, don't :-) Really, loadavg is a stupid metric. Yes... stupid, but unfortunately everyone is looking at it :( > >> I'm totally new to the scheduler code. > > Luckily you won't actually have to touch much of it. Most of the actual > loadavg code lives in the first ~400 lines of kernel/sched/proc.c, read > and weep. Its one of the best documented bits around. I looked trough it but I don't understand how to introduce the per cgroup calculation. I looked trough the headers and found the following, which is already implemented. task->sched_task_group->load_avg task->sched_task_group->cfs_rq->load_avg task->sched_task_group->cfs_rq->load.weight task->sched_task_group->cfs_rq->runnable_load_avg Unfortunately there is almost no documentation for these elements of the cfs_rq and task_group structs. It seams to me that part of the per task group loadavg code is already present. > > Your proposition however is extremely expensive, you turn something > that's already expensive O(nr_cpus) into something O(nr_cpus * > nr_cgroups). > > I'm fairly sure people will not like that, esp. for something of such > questionable use as the loadavg -- its really only a pretty number that > doesn't mean all that much. I know that its use is questionable but in my case I need to have it, or I will not be able to offer correct loadavg values in the containers. > >> -------- Original Message -------- >> From: Li Zefan >> >> Then you should add Peter, Ingo and LKML to your Cc list. :) > > You failed that, let me fix that. > >