Re: [RFC PATCH 3/5] mm/damon/core: floor effective quota size at minimum region size

[SeongJae Park]

On Sat, 16 May 2026 14:03:55 -0700 Ravi Jonnalagadda <ravis.opensrc@xxxxxxxxx> wrote:

> The CONSIST quota goal tuner initializes esz_bp to 0, producing an
> effective quota size (esz) of 1 byte on the first tick.
> damos_quota_is_full() rejects all regions when esz < min_region_sz
> (default PAGE_SIZE = 4096), so no regions can be tried and no
> feedback reaches the tuner — a bootstrapping deadlock.

That depend on whether the goal is already [over]-achieved.  If the goal is
achieved, the tuner will think no change is needed, so keep the
effectively-zero quota.  If the goal is over-achived, the tuner will think the
DAMOS scheme should be less aggressive, but it is already effectively-zero
quota, so keep having effectively-zero quota.

If the ogal is under-achived, the logic will iteratively increase the internal
esz (esz_bp), until it exceeds the min_region_sz, and finally start making some
effects.

So, unless the goal is already [over]-achieved, there is no deadlock.  If the
goal is already [over]-achieved, why we would want to make DAMOS do something?

Am I missing something?

I'd like to discuss this high level thing first, before digging deep into the
details.


Thanks,
SJ

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