From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH] cpuset: Enforce that a child's cpus must be a subset of
 the parent
Date: Wed, 6 Jun 2018 13:56:35 -0700
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>, Zefan Li <lizefan@huawei.com>, Johannes Weiner <hannes@cmpxchg.org>, Ingo Molnar <mingo@redhat.com>, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith <efault@gmx.de>, torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>, Juri Lelli <juri.lelli@redhat.com>, Patrick Bellasi <patrick.bellasi@arm.com>

Hello, Peter.

Sorry about late reply.

On Thu, May 31, 2018 at 06:38:26PM +0200, Peter Zijlstra wrote:
> > Yeah, for cpuset, it's messier, but it isn't different from hotunplug
> > scenario, right?  I think the best we can do there is putting ancestor
> > operation on an equal footing as hotplug ops.
> 
> Right, but hotplug is exceedingly rare, while I get the impression you
> think it is perfectly fine to recind on your resource grants.

Well, yeah, for a trivial example, imagine dynamic workload management
where you wanna restrict what a side-loaded batch workload can do on
and off peak hours.  All other controllers can do that.  It'd be a
really odd design trade-off if we make that really clumsy for cpuset
especially given that we wouldn't be gaining any actual
functionalities.

Thanks.

-- 
tejun