linux-kernel - Re: [PATCH v2] sched/fair: sanitize vruntime of entity being migrated

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] [day] [month] [year] [list]

Message-ID: <ZB0hiXUaXQ1v7r7O@chenyu5-mobl1>
Date:   Fri, 24 Mar 2023 12:05:29 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
CC:     <mingo@...hat.com>, <peterz@...radead.org>,
        <juri.lelli@...hat.com>, <dietmar.eggemann@....com>,
        <rostedt@...dmis.org>, <bsegall@...gle.com>, <mgorman@...e.de>,
        <bristot@...hat.com>, <vschneid@...hat.com>,
        <linux-kernel@...r.kernel.org>, <zhangqiao22@...wei.com>,
        kernel test robot <yujie.liu@...el.com>
Subject: Re: [PATCH v2] sched/fair: sanitize vruntime of entity being migrated

On 2023-03-17 at 17:08:10 +0100, Vincent Guittot wrote:
> Commit 829c1651e9c4 ("sched/fair: sanitize vruntime of entity being placed")
> fixes an overflowing bug, but ignore a case that se->exec_start is reset
> after a migration.
> 
> For fixing this case, we delay the reset of se->exec_start after
> placing the entity which se->exec_start to detect long sleeping task.
> 
> In order to take into account a possible divergence between the clock_task
> of 2 rqs, we increase the threshold to around 104 days.
> 
> 
> Fixes: 829c1651e9c4 ("sched/fair: sanitize vruntime of entity being placed")
> Signed-off-by: Zhang Qiao <zhangqiao22@...wei.com>
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
>
This patch has been confirmed by 0day to restore the performance which was decreased
by 829c1651e9c4[1], thanks for the fix.

commit:     a2e90611b9f425ad            829c1651e9c4a6f78398d3e6765          a53ce18cacb477dd0513c607f18

hackbench
throughput: 173811           -18.4%     141887                     +1.4%     176324

[1] https://lore.kernel.org/lkml/202303091155.672f546a-yujie.liu@intel.com/

thanks,
Chenyu