Re: [PATCH 4/5] mm: support batched checking of the young flag for MGLRU

[Baolin Wang]

On 2/26/26 5:08 PM, David Hildenbrand (Arm) wrote:
> > > > +            pte_t pteval = ptep_get(pvmw.pte);
> > >
> > > I wonder if there could be a way to avoid this ptep_get() by letting
> > > page_vma_mapped_walk() just provide the last value it used (in
> > > check_pte() I guess). Something for another patch.
> >
> > Well, we’d need to add a new field to ‘struct page_vma_mapped_walk’ to
> > store the last value (e.g., pvmw.pteval),
>
> Yes.
>
> > but this makes me wonder if it
> > is worth adding a new field just to avoid a lightweight read (which
> > should have no obvious performance impact).
>
> You recall that ptep_get() on arm64 is not that lightweight due to
> con-pte? :)
>
> But yeah, something for another day.

OK.

> > > What is "batched"? Did you mean "nr_ptes" ? Or just the initial value
> > > for "nr" ?
> >
> > There is already an 'nr' variable in this function. "nr_ptes" sounds
> > good to me, and will use it.
>
> You can just use "nr" here and reuse it for the existing variable?
>
> Both have the same semantics (nr of ptes / pages), so having a single
> value might cause less confusion.

Sure. Will do.