From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753706Ab2E3Mou (ORCPT ); Wed, 30 May 2012 08:44:50 -0400 Received: from casper.infradead.org ([85.118.1.10]:44965 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753371Ab2E3Mos convert rfc822-to-8bit (ORCPT ); Wed, 30 May 2012 08:44:48 -0400 Message-ID: <1338381877.26856.272.camel@twins> Subject: Re: [PATCH v3 5/6] Also record sleep start for a task group From: Peter Zijlstra To: Glauber Costa Cc: Paul Turner , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, devel@openvz.org, Tejun Heo , "Eric W. Biederman" , handai.szj@gmail.com, Andrew.Phillips@lmax.com, Serge Hallyn Date: Wed, 30 May 2012 14:44:37 +0200 In-Reply-To: <4FC61188.8000908@parallels.com> References: <1338371317-5980-1-git-send-email-glommer@parallels.com> <1338371317-5980-6-git-send-email-glommer@parallels.com> <4FC61188.8000908@parallels.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-05-30 at 16:24 +0400, Glauber Costa wrote: > sleep_start is not for iowait. This is for idle. And I know no other way > to collect idle time per cgroup, other than the time during which it was > out of the runqueue. > > Now what you say about the sleepers don't make that much sense for idle > because this information is per-cpu as well. > > When the se is being dequeued, it means none of its children is running > on that runqueue. That's idle. But does that mean the cgroup is idle? Its impossible to re-construct the machine state from this per-cpu data if your definition of cgroup-idle is the time when _all_ cpus are idle.