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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CACSyD1N2CjY-yqcSg+Q6KHKGzzQnio9HjwUHutup+FEX08wg0g@mail.gmail.com>
Date: Sat, 24 May 2025 10:09:36 +0800
From: Zhongkun He <hezhongkun.hzk@...edance.com>
To: Tejun Heo <tj@...nel.org>
Cc: Waiman Long <llong@...hat.com>, 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 Sat, May 24, 2025 at 9:14 AM Tejun Heo <tj@...nel.org> wrote:
>
> Hello,
>
> On Sat, May 24, 2025 at 09:10:21AM +0800, Zhongkun He wrote:
> ...
> > We move the task by modifying the cpuset.cpus and cpuset.mems and
> > the memory migration is an option with cpuset.memory_migrate
> > interface in V1. After we relocate the threads, the memory will be
> > migrated by syscall move_pages in userspace slowly, within a few
> > minutes.
> >
> > Presently, cpuset.mems triggers synchronous memory migration,
> > leading to prolonged and unacceptable service downtime in V2.
> >
> > So we hope to add back an interface similar to cgroup v1, optional
> > the migration.
>
> Ah, I see, so it's not that you aren't migrating the memory but more that
> the migration through cpuset.mems is too aggressive and causes disruption.
> Is that the right understanding?

Yes, exactly.

>
> If so, would an interface to specify the rate of migration be a better
> interface?
>

Per my understanding,  the interface of migration rate is far more complex.
To slow down the migration, moving it to the userspace can also help determine
when to carry out this operation.

Perhaps we can give it a try if there is a elegant code implementation which
can help the people do not migrate it in userspace.
If that path doesn't work, it's okay for us to disable the migration.

> Thanks.
>
> --
> tejun