Re: [PATCH 1/2] mm/damon/core: score an unmeasured PSI goal as not achieved for the temporal tuner

[Karl Mehltretter <kmehltretter@gmail.com>]

On Tue, Sep 15, 2026 at 07:50:54AM +0100, SJ Park wrote:
> 
> The intention is to make no effect this round.  Setting current_value to zero
> to temporal tuner means it will now have highest quota it could have.  If the
> effective quota before this was zero, it gets an effect.
> 
> Ideally, we should somehow remember what was the last esz and keep it.  I have
> no good idea for doing that with minimum change.  This is a corner case in my
> opinion (correct me if I'm wrong) so I want to keep the change as simple as
> possible.
> 
> If there is not easy way to do that, I think just keeping the behavior but
> making it explicitly explained might be better.
> 

Hello SJ,

I believe I have a version that addresses your concern without adding
too much complexity.

In short, it leaves the tuners as they are and instead keeps
last_psi_total across a commit of an existing PSI goal, as the code
did before a68878f83ae6. The U64_MAX round then happens only once per
new goal.

That also covers anything that commits before every tuning round,
like the user_input feedback path or "damo tune", which currently
never gets a measured round on either tuner.

I will test that and send it as v2.

Thanks,
Karl