linux-kernel - Re: [PATCH v3 09/14] cpuset: Don't use the cpu_possible

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: <20201119092922.GC2416649@google.com>
Date:   Thu, 19 Nov 2020 09:29:22 +0000
From:   Quentin Perret <qperret@...gle.com>
To:     Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Qais Yousef <qais.yousef@....com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        kernel-team@...roid.com
Subject: Re: [PATCH v3 09/14] cpuset: Don't use the cpu_possible_mask as a
 last resort for cgroup v1

On Friday 13 Nov 2020 at 09:37:14 (+0000), Will Deacon wrote:
> If the scheduler cannot find an allowed CPU for a task,
> cpuset_cpus_allowed_fallback() will widen the affinity to cpu_possible_mask
> if cgroup v1 is in use.
> 
> In preparation for allowing architectures to provide their own fallback
> mask, just return early if we're not using cgroup v2 and allow
> select_fallback_rq() to figure out the mask by itself.
> 
> Cc: Li Zefan <lizefan@...wei.com>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Signed-off-by: Will Deacon <will@...nel.org>

That makes select_fallback_rq() slightly more expensive if you're using
cgroup v1, but I don't expect that be really measurable in real-world
workloads, so:

Reviewed-by: Quentin Perret <qperret@...gle.com>

Thanks,
Quentin