Re: [PATCH 3/3 V8] workqueue: Allow modifying low level unbound workqueue cpumask

From: Mike Galbraith
Date: Tue Apr 28 2015 - 00:36:57 EST


On Mon, 2015-04-27 at 23:44 -0400, Tejun Heo wrote:

> > So, we need an API to modify the wq_unbound_cpumask, and I provided
> > this public function. Otherwise, the other code can't modify it.
>
> I see. I don't have too strong an opinion; however, changing the mask
> is a fairly heavy operation. Are there specific reasons why we don't
> want to follow the nohz config right away?

Isolation is not only applicable to nohz_full. Many loads are
unsuitable for nohz_full, yet require maximum isolation.

ATM, nohz_full is not dynamic, but hopefully one day will be. In the
here and now, we can isolate cores from the scheduler on the fly via
cpusets, a prime API user candidate.

-Mike

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