Re: [PATCH v4 04/17] mm/mglru: frequency guided workingset promotion (MGLRU-FG)

[sashiko-bot@kernel.org]

> From: Kairui Song <kasong@tencent.com>
> 
> Complement MGLRU's eviction-time tier-PID protection with access-time
> frequency-guided promotion.  Introduce a unified set of helpers built based
> on referenced (access) count of a folio.
> 
> Each access increments a folio's referenced count stored in folio flags
> (refs), refs still maps to a logarithmic tier just like before, but with
> more formal bit definitions, a few special thresholds are introduced:
> LRU_REFS_REFERENCED (1), LRU_REFS_WORKINGSET (2), LRU_REFS_PROTECTED (3),
> and LRU_REFS_MAX (7). When refs reaches a certain threshold, the folio is
> promoted proactively instead of waiting for the PID controller to kick in.
> 
> Also simplify MGLRU's usage of PG_workingset and PG_referenced: they
> become the low two bits of the refs count, with the higher bits
> [ ... ]
> PG_workingset and PG_referenced are no longer independent flags under
> MGLRU.  Adjusting existing raw folio_test_*() callers to the new
> semantics is left as follow-ups.
> 
> Signed-off-by: Kairui Song <kasong@tencent.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com?part=4