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

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Message-ID: <aDCnnd46qjAvoxZq@slm.duckdns.org>
Date: Fri, 23 May 2025 06:51:41 -1000
From: Tejun Heo <tj@...nel.org>
To: Zhongkun He <hezhongkun.hzk@...edance.com>
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

Hello,

On Fri, May 23, 2025 at 11:35:57PM +0800, Zhongkun He wrote:
> > 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.

I suppose we can add back an interface similar to cgroup1 but can you detail
the use case a bit? If you relocate threads without relocating memory, you'd
be paying on-going cost for memory access. It'd be great if you can
elaborate why such mode of operation is desirable.

Thanks.

-- 
tejun