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From:   Kalesh Singh <kaleshsingh@google.com>
Date:   Wed, 9 Aug 2023 08:54:23 -0700
Message-ID: <CAC_TJvckhxwz9TxXgMSaiihHddY+AnEGqjLxvO6qF0eqTb5U8Q@mail.gmail.com>
Subject: Re: [PATCH] Multi-gen LRU: skip CMA pages when they are not eligible
To:     David Hildenbrand <david@redhat.com>
Cc:     Charan Teja Kalla <quic_charante@quicinc.com>,
        akpm@linux-foundation.org, zhaoyang.huang@unisoc.com,
        yuzhao@google.com, surenb@google.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
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On Wed, Aug 9, 2023 at 7:00=E2=80=AFAM David Hildenbrand <david@redhat.com>=
 wrote:
>
> On 09.08.23 10:05, Charan Teja Kalla wrote:
> > This patch is based on the commit 5da226dbfce3("mm: skip CMA pages when
> > they are not available") which skips cma pages reclaim when they are no=
t
> > eligible for the current allocation context. In mglru, such pages are
> > added to the tail of the immediate generation to maintain better LRU
> > order, which is unlike the case of conventional LRU where such pages ar=
e
> > directly added to the head of the LRU list(akin to adding to head of th=
e
> > youngest generation in mglru).
> >
> > No observable issue without this patch on MGLRU, but logically it make
> > sense to skip the CMA page reclaim when those pages can't be satisfied
> > for the current allocation context.
> >
> > Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>

Reviewed-by: Kalesh Singh <kaleshsingh@google.com>

Thanks,
Kalesh

> > ---
> >   mm/vmscan.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index b4329f9..6cbe921 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -4943,7 +4943,7 @@ static bool sort_folio(struct lruvec *lruvec, str=
uct folio *folio, struct scan_c
> >       }
> >
> >       /* ineligible */
> > -     if (zone > sc->reclaim_idx) {
> > +     if (zone > sc->reclaim_idx || skip_cma(folio, sc)) {
> >               gen =3D folio_inc_gen(lruvec, folio, false);
> >               list_move_tail(&folio->lru, &lrugen->folios[gen][type][zo=
ne]);
> >               return true;
>
> Makes sense to me.
>
> --
> Cheers,
>
> David / dhildenb
>