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  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:   Sun, 22 Nov 2020 22:44:42 +1100
From:   Balbir Singh <>
To:     "Joel Fernandes (Google)" <>
Cc:     Nishanth Aravamudan <>,
        Julien Desfossez <>,
        Peter Zijlstra <>,
        Tim Chen <>,
        Vineeth Pillai <>,
        Aaron Lu <>,
        Aubrey Li <>,,,,,,,,
        Phil Auld <>,
        Valentin Schneider <>,
        Mel Gorman <>,
        Pawan Gupta <>,
        Paolo Bonzini <>,,
        Chen Yu <>,
        Christian Brauner <>,
        Agata Gruza <>,
        Antonio Gomez Iglesias <>,,,,,,,,
        Alexandre Chartre <>,,,
        Dhaval Giani <>,
        Junaid Shahid <>,,, Ben Segall <>,
        Josh Don <>, Hao Luo <>,
        Tom Lendacky <>,
        Aubrey Li <>,
        "Paul E. McKenney" <>,
        Tim Chen <>
Subject: Re: [PATCH -tip 09/32] sched/fair: Snapshot the min_vruntime of CPUs
 on force idle

On Tue, Nov 17, 2020 at 06:19:39PM -0500, Joel Fernandes (Google) wrote:
> During force-idle, we end up doing cross-cpu comparison of vruntimes
> during pick_next_task. If we simply compare (vruntime-min_vruntime)
> across CPUs, and if the CPUs only have 1 task each, we will always
> end up comparing 0 with 0 and pick just one of the tasks all the time.
> This starves the task that was not picked. To fix this, take a snapshot
> of the min_vruntime when entering force idle and use it for comparison.
> This min_vruntime snapshot will only be used for cross-CPU vruntime
> comparison, and nothing else.
> This resolves several performance issues that were seen in ChromeOS
> audio usecase.
> NOTE: Note, this patch will be improved in a later patch. It is just
>       kept here as the basis for the later patch and to make rebasing
>       easier. Further, it may make reverting the improvement easier in
>       case the improvement causes any regression.

This seems cumbersome, is there no way to track the min_vruntime via

Balbir Singh.

Powered by blists - more mailing lists