linux-kernel - Re: [PATCH 8/9] sched/psi: add kernel cmdline parameter psi_inner

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Message-ID: <Yuq3Q6Y9dRnjjcPt@slm.duckdns.org>
Date:   Wed, 3 Aug 2022 07:58:27 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Chengming Zhou <zhouchengming@...edance.com>
Cc:     Johannes Weiner <hannes@...xchg.org>, surenb@...gle.com,
        mingo@...hat.com, peterz@...radead.org, corbet@....net,
        akpm@...ux-foundation.org, rdunlap@...radead.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        songmuchun@...edance.com, cgroups@...r.kernel.org
Subject: Re: [PATCH 8/9] sched/psi: add kernel cmdline parameter
 psi_inner_cgroup

Hello,

On Wed, Aug 03, 2022 at 08:17:22PM +0800, Chengming Zhou wrote:
> > Assuming the above isn't wrong, if we can figure out how we can re-enable
> > it, which is more difficult as the counters need to be resynchronized with
> > the current state, that'd be ideal. Then, we can just allow each cgroup to
> > enable / disable PSI reporting dynamically as they see fit.
> 
> This method is more fine-grained but more difficult like you said above.
> I think it may meet most needs to disable PSI stats in intermediate cgroups?

So, I'm not necessarily against implementing something easier but we at
least wanna get the interface right, so that if we decide to do the full
thing later we can easily expand on the existing interface. ie. let's please
not be too hacky. I don't think it'd be that difficult to implement
per-cgroup disable-only operation that we can later expand to allow
re-enabling, right?

Thanks.

-- 
tejun