From: Tejun Heo <tj@kernel.org>
To: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Ripduman Sohan <Ripduman.Sohan@cl.cam.ac.uk>,
linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: Re: [PATCH] workqueue: Restore cpus_allowed mask for sleeping workqueue rescue threads
Date: Fri, 30 Sep 2011 01:09:14 -0700 [thread overview]
Message-ID: <20110930080914.GM10425@mtj.dyndns.org> (raw)
In-Reply-To: <CAOtvUMeGddgQK==K09uCVHOn8gbW2PaUaCiWhhOCNx8pvy8QiQ@mail.gmail.com>
Hello,
On Sun, Sep 25, 2011 at 09:02:25AM +0300, Gilad Ben-Yossef wrote:
> Thank you for taking the time to answer my query :-)
>
> I agree there is no real problem with having an additional task
> bound to an "isolated" CPU so long that it does not run and of
> course that if a task on an isolated CPU initiated activity that
> resulted in requiring the services of a rescuer workqueue thread it
> most certainly needs to run there and that is fine.
>
> I guess my question is - apart form running on the isolated CPU,
> does the fact that the rescuer thread is bound there can cause
> activity on that CPU originating from a foreign CPU, such as for
> example running an IPI handler in order to migrate it there?
Hmmm... indeed. This can cause an unnecessary wakeup / migration on
an isolated CPU when another CPU asks for the rescuer, so yeah it
makes sense to change the behavior. BTW, why didn't the original
patch simply use set_cpus_allowed_ptr(cpu_all_mask)?
Thanks.
--
tejun
next prev parent reply other threads:[~2011-09-30 8:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 13:36 [PATCH] workqueue: Restore cpus_allowed mask for sleeping workqueue rescue threads Ripduman Sohan
2011-09-02 0:29 ` Tejun Heo
2011-09-15 16:14 ` Ripduman Sohan
2011-09-17 0:29 ` Tejun Heo
2011-09-18 6:36 ` Gilad Ben-Yossef
2011-09-24 3:07 ` Tejun Heo
2011-09-25 6:02 ` Gilad Ben-Yossef
2011-09-30 8:09 ` Tejun Heo [this message]
2011-09-30 8:54 ` Ripduman Sohan
2011-09-30 8:57 ` Tejun Heo
2011-09-30 8:59 ` Ripduman Sohan
2011-10-01 1:10 ` Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2011-08-31 13:17 Ripduman Sohan
2011-08-31 15:20 ` Peter Zijlstra
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