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Subject: Re: [PATCH 07/41] cpuset: Set up interface for nohz flag
From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
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Date: Tue, 08 May 2012 17:27:12 +0200
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On Tue, 2012-05-08 at 10:18 -0500, Christoph Lameter wrote:
> On Tue, 8 May 2012, Peter Zijlstra wrote:
> 
> > There's no such policy, but I don't get why Christoph objects to
> > cpusets, its the option I would prefer. You're going to use cpusets
> > anyway to partition your system, might as well also use it to mark a
> > whole partition/set as nohz.
> 
> We are currently not using cpusets but are simply isolating processors as
> needed. Not sure that I want the overhead (administratively as well as in
> kernel) to deal with this.

isolating how? The only way to do that is with the (broken) isolcpus
crap and cpusets. There is no other way.

> Someone may be using a different partitioning technique (like cgroups) etc
> and then wont be able to use nohz. Having it not depend on cpusets makes
> it more universal.

You seem terminally confused on cpuset vs cgroups thing. One more time:
cpusets is a cgroup controller. Without cgroup support there is no
cpusets.

Furthermore there is no other partitioning scheme, cpusets is it.