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Date: Tue, 9 Feb 2016 12:54:00 -0500
From: Tejun Heo <tj@kernel.org>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>, Jiri Slaby <jslaby@suse.cz>,
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        Daniel Bilik <daniel.bilik@neosystem.cz>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: Crashes with 874bbfe600a6 in 3.18.25
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Hello, Mike.

On Tue, Feb 09, 2016 at 06:04:04PM +0100, Mike Galbraith wrote:
> workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs
> 
> WORK_CPU_UNBOUND work items queued to a bound workqueue always run
> locally.  This is a good thing normally, but not when the user has
> asked us to keep unbound work away from certain CPUs.  Round robin
> these to wq_unbound_cpumask CPUs instead, as perturbation avoidance
> trumps performance.

I don't think doing this by default for everyone is a good idea.  A
lot of workqueue usages tend to touch whatever the scheduler was
touching after all.  Doing things per-cpu is generally a pretty good
thing.

Thanks.

-- 
tejun