linux-kernel - Re: [PATCH v3] mm: add thp_utilization metrics to /proc/thp

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Message-ID: <CAHbLzkqGq6LDDSCcFTJW9_O8dfAMje8_W6ddpDP9ESDQWUb07w@mail.gmail.com>
Date:   Wed, 10 Aug 2022 10:07:32 -0700
From:   Yang Shi <shy828301@...il.com>
To:     Yu Zhao <yuzhao@...gle.com>
Cc:     "Alex Zhu (Kernel)" <alexlzhu@...com>, Rik van Riel <riel@...com>,
        Kernel Team <Kernel-team@...com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        Ning Zhang <ningzhang@...ux.alibaba.com>
Subject: Re: [PATCH v3] mm: add thp_utilization metrics to /proc/thp_utilization

On Tue, Aug 9, 2022 at 4:36 PM Yu Zhao <yuzhao@...gle.com> wrote:
>
> On Tue, Aug 9, 2022 at 11:16 AM Alex Zhu (Kernel) <alexlzhu@...com> wrote:
> >
> >
> > > OK, it is hard to tell what it looks like now. But the THPs on the
> > > deferred split list may be on the "low utilization split" list too?
> > > IIUC the major difference is to replace zero-filled subpage to special
> > > zero page, so you implemented another THP split function to handle it?
> > >
> > > Anyway the code should answer the most questions.
> >
> > They can indeed end up on both lists. This did have to be handled when
> > implementing the shrinker.
> >
> > We free the zero filled subpages, while modifying the existing split_huge_page()
> > function. Will follow up that change in another patch.
>
> FYI. This series does it:
>
> https://lore.kernel.org/r/20210731063938.1391602-1-yuzhao@google.com/
>
> And this one:
>
> https://lore.kernel.org/r/1635422215-99394-1-git-send-email-ningzhang@linux.alibaba.com/

Thanks, Yu. I totally forgot about these series. It is time to refresh
my memory.