linux-kernel - Re: [PATCH v2] sched/fair: fix sgc->{min,max}

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]

Date:   Mon, 6 Jan 2020 11:23:41 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Peng Liu <iwtbavbm@...il.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, qais.yousef@....com, morten.rasmussen@....com,
        valentin.schneider@....com
Subject: Re: [PATCH v2] sched/fair: fix sgc->{min,max}_capacity miscalculate

On Sat, Jan 04, 2020 at 09:08:28PM +0800, Peng Liu wrote:
> commit bf475ce0a3dd ("sched/fair: Add per-CPU min capacity to
> sched_group_capacity") introduced per-cpu min_capacity.
> 
> commit e3d6d0cb66f2 ("sched/fair: Add sched_group per-CPU max capacity")
> introduced per-cpu max_capacity.
> 
> Here, capacity is the accumulated sum of (maybe) many CPUs' capacity.
> Compare with capacity to get {min,max}_capacity makes no sense. Instead,
> we should compare one by one in each iteration to get
> sgc->{min,max}_capacity of the group.
> 
> Also, the only CPU in rq->sd->groups should be rq's CPU. Thus,
> capacity_of(cpu_of(rq)) should be equal to rq->sd->groups->sgc->capacity.
> Code can be simplified by removing the if/else.
> 
> Signed-off-by: Peng Liu <iwtbavbm@...il.com>
> Reviewed-by: Valentin Schneider <valentin.schneider@....com>
> ---
> v1: https://lkml.org/lkml/2019/12/30/502

Please (for future use); use the form:

  https://lkml.kernel.org/r/$msgid