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Date: Fri, 24 Jan 2014 14:23:13 +0530
Message-ID: <CAKohpom4vuqfVc=Bw1ak0g-7LiVT4rpLcaUTSyACEJb__1O4aQ@mail.gmail.com>
Subject: Re: [QUERY]: Is using CPU hotplug right for isolating CPUs?
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lei Wen <adrian.wenl@gmail.com>, Kevin Hilman <khilman@linaro.org>,
        Lists linaro-kernel <linaro-kernel@lists.linaro.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linaro Networking <linaro-networking@linaro.org>,
        Tejun Heo <tj@kernel.org>
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On 23 January 2014 19:31, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> Ok, so it is fine to migrate the latter kind I guess?

Unless somebody has abused the API and used bound workqueues where he
should have used unbound ones.

> I haven't checked the details but then this quiesce option would involve
> a dependency on cpuset for any workload involving workqueues affinity. I'm
> not sure we really want this. Besides, workqueues have an existing sysfs interface
> that can be easily extended.
>
> Now indeed we may also want to enforce some policy to make sure that further
> created and queued workqueues are affine to a specific subset of CPUs. And then
> cpuset sounds like a good idea :)

Exactly. Cpuset would be more useful here. Probably we can keep both cpusets
and sysfs interface of workqueues..

I will try to add this option under cpuset which will initially move timers and
workqueues away from the cpuset in question.
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