From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v3 5/6] Also record sleep start for a task group Date: Wed, 30 May 2012 14:44:37 +0200 Message-ID: <1338381877.26856.272.camel@twins> References: <1338371317-5980-1-git-send-email-glommer@parallels.com> <1338371317-5980-6-git-send-email-glommer@parallels.com> <4FC61188.8000908@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <4FC61188.8000908-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Glauber Costa Cc: Paul Turner , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Tejun Heo , "Eric W. Biederman" , handai.szj-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Andrew.Phillips-xheW4WVAX9Y@public.gmane.org, Serge Hallyn 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.