linux-kernel - Re: [PATCH 00/10] workqueue: break affinity initiatively

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Date:   Tue, 15 Dec 2020 16:14:26 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        Hillf Danton <hdanton@...a.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Qian Cai <cai@...hat.com>,
        Vincent Donnefort <vincent.donnefort@....com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 00/10] workqueue: break affinity initiatively

On Tue, Dec 15, 2020 at 3:50 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Tue, Dec 15, 2020 at 01:44:53PM +0800, Lai Jiangshan wrote:
> > I don't know how the scheduler distinguishes all these
> > different cases under the "new assumption".
>
> The special case is:
>
>   (p->flags & PF_KTHREAD) && p->nr_cpus_allowed == 1
>
>

So unbound per-node workers can possibly match this test. So there is code
needed to handle for unbound workers/pools which is done by this patchset.

Is this the code of is_per_cpu_kthread()? I think I should have also
used this function in workqueue and don't break affinity for unbound
workers have more than 1 cpu.