Re: [PATCH 3/3] mm, lru_gen: try to prefetch next page when canning LRU

[Suren Baghdasaryan]

On Mon, Dec 25, 2023 at 7:42 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Sun, Dec 24, 2023 at 11:41:31PM -0700, Yu Zhao wrote:
> > On Fri, Dec 22, 2023 at 3:24 AM Kairui Song <ryncsn@xxxxxxxxx> wrote:
> > >
> > > From: Kairui Song <kasong@xxxxxxxxxxx>
> > >
> > > Prefetch for inactive/active LRU have been long exiting, apply the same
> > > optimization for MGLRU.
> >
> > I seriously doubt that prefetch helps in this case.
> >
> > Willy, any thoughts on this? Thanks.
>
> It _might_ ... highly depends on microarchitecture.  My experience is
> that it offers more benefit on AMD than on Intel, but that experience
> is several generations out of date and it may just not be applicable to
> modern AMD.
>
> It's probably more effective on ARM Cortex A cores than on ARM Cortex X
> cores ... maybe we can get someone from Android (Suren?) to do some
> testing?

Android is quite noisy and I'm afraid a small improvement like this
would not be distinguishable from noise unless it's much more
pronounced. I'll take a stab but don't hold your breath.