linux-kernel - Re: [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <Y71RBDZqV1Ad+GVr@tpad>
Date:   Tue, 10 Jan 2023 08:50:28 -0300
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     Hillf Danton <hdanton@...a.com>
Cc:     atomlin@...mlin.com, frederic@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context
 when NOHZ full

On Tue, Jan 10, 2023 at 10:43:56AM +0800, Hillf Danton wrote:
> On 9 Jan 2023 11:12:49 -0300 Marcelo Tosatti <mtosatti@...hat.com>
> > 
> > Yes, but if you do not return to userspace, then the per-CPU vm
> > statistics can be dirty indefinitely.
> 
> Could you specify the reasons for failing to return to userspace,
> given it is undesired intereference for the shepherd to queue work
> on the isolated CPUs.

Any system call that takes longer than the threshold to sync vmstats.

Or a long running kernel thread, for example:

https://stackoverflow.com/questions/65111483/long-running-kthread-and-synchronize-net