linux-kernel - Re: [PATCH 1/2] sched: Optimise task_mm_cid

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Message-ID: <36f3b1a59604394d861ad89230a3d56231d2cae4.camel@redhat.com>
Date: Mon, 02 Dec 2024 16:59:24 +0100
From: Gabriele Monaco <gmonaco@...hat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Ingo Molnar	
 <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Juri Lelli	
 <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
 Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt
 <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,  Mel Gorman
 <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] sched: Optimise task_mm_cid_work duration



On Mon, 2024-12-02 at 10:01 -0500, Mathieu Desnoyers wrote:
> 
> mm_cpus_allowed can be updated dynamically by setting cpu affinity
> and changing the cpusets. If we change the iteration from each
> possible
> cpus to allowed cpus, then we need to adapt the allowed cpus updates
> with the associated updates to the mm_cid as well. This is adding
> complexity.
> 
> I understand that you wish to offload this task_work to a non-
> isolated
> CPU (non-RT). If you do so, do you really care about the duration of
> task_mm_cid_work enough to justify the added complexity to the
> cpu affinity/cpusets updates ?
> 

Well, no we don't really care at this point.. If it isn't a quick win
I'd say I can simply remove it from the patchset, for the current use
case it doesn't really matter.

Thanks for the analysis.
Gabriele