From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Daniel P. Berrange" <berrange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH cgroup/for-3.11 1/3] cgroup: mark "tasks" cgroup file as
	insane
Date: Tue, 4 Jun 2013 12:15:56 +0100
Message-ID: <20130604111556.GA4963@redhat.com>
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, kay.sievers-tD+1rO4QERM@public.gmane.org, Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>, lennart-mdGvqq1h2p+GdvJs77BJ7Q@public.gmane.org, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

On Mon, Jun 03, 2013 at 07:13:02PM -0700, Tejun Heo wrote:
> Some resources controlled by cgroup aren't per-task and cgroup core
> allowing threads of a single thread_group to be in different cgroups
> forced memcg do explicitly find the group leader and use it.  This is
> gonna be nasty when transitioning to unified hierarchy and in general
> we don't want and won't support granularity finer than processes.

With libvirt and KVM we require the ability to put different threads
in different cgroups for the "cpu", "cpuset" & "cpuacct" controllers.
This is to allow us to control schedular tunables / placement for
QEMU vCPU threads, independantly of limits for QEMU I/O threads. So
requiring all threads of a process to be in the same cgroup isn't
sufficiently flexible for our needs.

We don't care about this for the other non-CPU related controllers
though.

Daniel
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