From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH 0/4] x86: Add Cache QoS Monitoring (CQM) support
Date: Mon, 6 Jan 2014 18:53:38 +0100
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To: "Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: "containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

On Mon, Jan 06, 2014 at 04:47:57PM +0000, Waskiewicz Jr, Peter P wrote:
> > Yeah that's not accurate, nor desired I think, because you get into
> > horrible problems with hierarchies, do child groups belong to your RMID
> > or not?
> 
> I'd rather not support a child group of a child group.  Only groups off
> the root, and each group would be assigned an RMID when it's activated
> for monitoring.

Yeah, that's a complete non started for cgroups. Cgroups need to be
completely hierarchical.

So even the root group should represent all tasks; which if you fragment
RMIDs on child cgroups doesn't work anymore.