linux-kernel - Re: [PATCH 1/2] sched/fair: Fix how load gets propagated from cfs_rq to its sched

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]

Date:   Mon, 1 May 2017 16:52:23 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Tejun Heo <tj@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>, Paul Turner <pjt@...gle.com>,
        Chris Mason <clm@...com>, kernel-team@...com
Subject: Re: [PATCH 1/2] sched/fair: Fix how load gets propagated from cfs_rq
 to its sched_entity

On Mon, May 01, 2017 at 04:17:33PM +0200, Peter Zijlstra wrote:

> So this here does:
> 
>   ( tg->load_avg = \Sum cfs_rq->load_avg )
> 
>   load      = cfs_rq->load.weight
> 
>   tg_weight = tg->load_avg - cfs_rq->contrib + load
> 
> 
>            tg->shares * load
>   shares = -----------------
>                tg_weight
> 
> 
>                         cfs_rq->load_avg
>   avg_shares = shares * ----------------
>                               load
> 
> 	       tg->shares * cfs_rq->load_avg
>              = -----------------------------
>                       tg_weight
> 
> 
>   ( se->load.weight = shares )
> 
>   se->load_avg = min(shares, avg_shares);

I wonder though; do we really need the min() ? Can't we simply use
avg_shares all the time?