linux-kernel - Re: [PATCHSET wq/for-3.10] workqueue: NUMA affinity for unbound workqueues

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Message-ID: <CACvQF53=qgUHrr944D_70dZpT-EOMtPcz2+0JPp4kOnGPzAptQ@mail.gmail.com>
Date:	Mon, 25 Mar 2013 00:04:19 +0800
From:	Lai Jiangshan <eag0628@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	laijs@...fujitsu.com, axboe@...nel.dk, jack@...e.cz,
	fengguang.wu@...el.com, jmoyer@...hat.com, zab@...hat.com,
	linux-kernel@...r.kernel.org, herbert@...dor.apana.org.au,
	davem@...emloft.net, linux-crypto@...r.kernel.org
Subject: Re: [PATCHSET wq/for-3.10] workqueue: NUMA affinity for unbound workqueues

Hi, TJ

After long time(again) thought.

I think this patchset has this problem:
the work may be running on wrong CPU when
there is online cpu in its wq's cpumask.

example:
node0(cpu0,cpu1),node1(cpu2,cpu3),
wq's cpumask: 1,3
the pwq of this wq on the node1's cpumask: 3
current online cpu: 0-2.
so the cpumask of worker tasks of the pwq on node1 is actually cpu_all_mask.
so the work scheduled from cpu2 can be executed on cpu0 or cpu2.
we expect it is executed on cpu1 only.

It can be fixed by swapping pwqs(node's pwq <-> default pwq)
when cpuhotplug. But could you reschedule this patchset to wq/for-3.11?
the whole patchset is more complicated than my brain.

If you agree, I will rebase my patches again.

Thanks,
Lai

On Thu, Mar 21, 2013 at 2:57 AM, Tejun Heo <tj@...nel.org> wrote:
> On Tue, Mar 19, 2013 at 05:00:19PM -0700, Tejun Heo wrote:
>> and also available in the following git branch.
>>
>>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git review-numa
>
> Branch rebased on top of the current wq/for-3.10 with updated patches.
> The new comit ID is 9555fbc12d786a9eae7cf7701a6718a0c029173e.
>
> Thanks.
>
> --
> tejun
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