Subject: Re: [RFC/RFT PATCH v3] sched: automated per tty task groups
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Menage <menage@google.com>,
        Samuel Thibault <samuel.thibault@ens-lyon.org>,
        Hans-Peter Jansen <hpj@urpla.net>, linux-kernel@vger.kernel.org,
        Lennart Poettering <mzxreary@0pointer.de>,
        Linus Torvalds <torvalds@linux-foundation.org>, david@lang.hm,
        Dhaval Giani <dhaval.giani@gmail.com>, Vivek Goyal <vgoyal@redhat.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Markus Trippelsdorf <markus@trippelsdorf.de>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Ingo Molnar <mingo@elte.hu>, Balbir Singh <balbir@linux.vnet.ibm.com>
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Date: Fri, 19 Nov 2010 06:03:34 -0700
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On Fri, 2010-11-19 at 13:51 +0100, Peter Zijlstra wrote:
> On Fri, 2010-11-19 at 04:31 -0800, Paul Menage wrote:
> > On Fri, Nov 19, 2010 at 3:49 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > > It must be nice to be that ignorant ;-) Speaking for the scheduler
> > > cgroup controller (that being the only one I actually know), most all
> > > the load-balance operations are O(n) in the number of active cgroups,
> > > and a lot of the cpu local schedule operations are O(d) where d is the
> > > depth of the cgroup tree.
> > 
> > The same would apply to CPU autogroups, presumably?
> 
> Yep, they're not special at all... uses the same mechanism.

The only difference is cost of creation and destruction, so cgroups and
autogroups suck boulders of slightly different diameter when creating
and/or destroying at high frequency.

	-Mike


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