linux-kernel - Re: [RFC][PATCH 1/5] sched/fair: Fix select_idle

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: <CAKfTPtDk3+96ZuytRAPA3ZBqW-whzn3cbGmwgS7ZfyoPaTTKnA@mail.gmail.com>
Date:   Mon, 11 Jan 2021 15:39:29 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Mel Gorman <mgorman@...hsingularity.net>,
        "Li, Aubrey" <aubrey.li@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Qais Yousef <qais.yousef@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Jiang Biao <benbjiang@...il.com>
Subject: Re: [RFC][PATCH 1/5] sched/fair: Fix select_idle_cpu()s cost accounting

On Fri, 8 Jan 2021 at 20:45, Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Jan 08, 2021 at 04:10:51PM +0100, Vincent Guittot wrote:
> > Also, there is another problem (that I'm investigating)  which is that
> > this_rq()->avg_idle is stalled when your cpu is busy. Which means that
> > this avg_idle can just be a very old and meaningless value. I think
> > that we should decay it periodically to reflect there is less and less
>
> https://lkml.kernel.org/r/20180530143105.977759909@infradead.org
>
> :-)

:-)

I was more thinking of something like decaying avg_idle during
tick_fair but at leat we all agree that we can't stay with a stalled
avg_idle value