linux-kernel - Re: [PATCH v3 3/7] sched/fair: Add more sched_asym

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

Message-ID: <87tupcrziq.mognet@arm.com>
Date:   Mon, 15 Mar 2021 19:24:29 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Rik van Riel <riel@...riel.com>,
        Qais Yousef <qais.yousef@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Quentin Perret <qperret@...gle.com>,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        Lingutla Chandrasekhar <clingutla@...eaurora.org>
Subject: Re: [PATCH v3 3/7] sched/fair: Add more sched_asym_cpucapacity static branch checks


Hi Vincent,

Thanks for taking another look at this.

On 15/03/21 15:18, Vincent Guittot wrote:
> On Thu, 11 Mar 2021 at 13:05, Valentin Schneider
> <valentin.schneider@....com> wrote:
>>
>> Rik noted a while back that a handful of
>>
>>   sd->flags & SD_ASYM_CPUCAPACITY
>>
>> & family in the CFS load-balancer code aren't guarded by the
>> sched_asym_cpucapacity static branch.
>
> guarding asym capacity with static branch in fast path makes sense but
> I see no benefit in this slow path but hiding and complexifying the
> code. Also if you start with this way then you have to add a nop in
> all other places where flag or a group_type might be unused.
>

OK, fair enough, I'll drop this one.