linux-kernel - Re: [PATCH v6 0/2] Fix nohz

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Message-ID: <20230731151751.GC232229@lorien.usersys.redhat.com>
Date:   Mon, 31 Jul 2023 11:17:51 -0400
From:   Phil Auld <pauld@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Juri Lelli <juri.lelli@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Valentin Schneider <vschneid@...hat.com>,
        Ben Segall <bsegall@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mel Gorman <mgorman@...e.de>,
        Frederic Weisbecker <frederic@...nel.org>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH v6 0/2] Fix nohz_full vs cfs bandwidth


Hi Peter,

On Wed, Jul 12, 2023 at 09:33:55AM -0400 Phil Auld wrote:
> This is v6 of patch 2/2 which is adding code to prevent
> the tick from being stopped when the single running task
> has bandwidth limits. Discussions had led to the idea of
> adding a bit to task_struct to help make this decision.
> 
> There was some complexity with doing it in the task which
> is  avoided by using something in the cfs_rq. Looking 
> into that lead me to the hierarchical_quota field in the 
> cfs_bandwith struct. We spend a good deal of effort
> updating (or trying to, see patch 1/2) that value for
> the whole task_group tree when a quota is set/changed.
> 
> This new version first fixes that value to be meaningful
> for cgroupv2 and then leverages it to make the decisions
> about blocking the tick_stop. 
> 
> Phil Auld (2):
>   sched, cgroup: Restore meaning to hierarchical_quota
>   Sched/fair: Block nohz tick_stop when cfs bandwidth in use
> 
>  kernel/sched/core.c     | 23 ++++++++++++++---
>  kernel/sched/fair.c     | 56 ++++++++++++++++++++++++++++++++++++++---
>  kernel/sched/features.h |  2 ++
>  kernel/sched/sched.h    |  3 ++-
>  4 files changed, 76 insertions(+), 8 deletions(-)
> 
> -- 
> 2.31.1
> 

Ping :)

Any thoughts on these now?


Cheers,
Phil
--