linux-kernel - Re: [External] Re: [PATCH] cpuset: introduce non-blocking cpuset.mems setting option

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Message-ID: <CACSyD1P+wuSP2jhMsLHBAXDxGoBkWzK54S5BRzh63yby4g0OHw@mail.gmail.com>
Date: Fri, 23 May 2025 23:35:57 +0800
From: Zhongkun He <hezhongkun.hzk@...edance.com>
To: Tejun Heo <tj@...nel.org>
Cc: Waiman Long <llong@...hat.com>, hannes@...xchg.org, cgroups@...r.kernel.org, 
	linux-kernel@...r.kernel.org, muchun.song@...ux.dev
Subject: Re: [External] Re: [PATCH] cpuset: introduce non-blocking cpuset.mems
 setting option

On Fri, May 23, 2025 at 3:03 AM Tejun Heo <tj@...nel.org> wrote:
>
> Hello,
>
> On Thu, May 22, 2025 at 11:37:44AM +0800, Zhongkun He wrote:
> > > I don't think this is a good idea. O_NONBLOCK means "don't wait", not "skip
> > > this".
> >
> > Yes, I agree.  However, we have been experiencing this issue for a long time,
> > so we hope to have an option to disable memory migration in v2.
> >
> > Would it be possible to re-enable the memory.migrate interface and
> > disable memory migration by default in v2?
> >
> > Alternatively, could we introduce an option in cpuset.mems to explicitly
> > indicate that memory migration should not occur?
> >
> > Please feel free to share any suggestions you might have.
>
> Is this something you want on the whole machine? If so, would global cgroup
> mount option work?

It doesn't apply to the whole machine. It is only relevant to the pod
with huge pages,
where the service will be unavailable for over ten seconds if modify
the cpuset.mems.
Therefore, it would be ideal if there were an option to disable the migration
for this special case.

Thanks.

>
> Thanks.
>
> --
> tejun
>