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From:   Yu Zhao <yuzhao@google.com>
Date:   Wed, 10 Aug 2022 11:54:09 -0600
Message-ID: <CAOUHufYeuMN9As58BVwMKSN6viOZKReXNeCBgGeeL6ToWGsEKw@mail.gmail.com>
Subject: Re: [PATCH v3] mm: add thp_utilization metrics to /proc/thp_utilization
To:     "Alex Zhu (Kernel)" <alexlzhu@fb.com>
Cc:     Yang Shi <shy828301@gmail.com>, Rik van Riel <riel@fb.com>,
        Kernel Team <Kernel-team@fb.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "willy@infradead.org" <willy@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
        Ning Zhang <ningzhang@linux.alibaba.com>,
        Miaohe Lin <linmiaohe@huawei.com>
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On Wed, Aug 10, 2022 at 11:15 AM Alex Zhu (Kernel) <alexlzhu@fb.com> wrote:
>
>
> > On Aug 10, 2022, at 10:07 AM, Yang Shi <shy828301@gmail.com> wrote:
> >
> > On Tue, Aug 9, 2022 at 4:36 PM Yu Zhao <yuzhao@google.com> wrote:
> >>
> >> On Tue, Aug 9, 2022 at 11:16 AM Alex Zhu (Kernel) <alexlzhu@fb.com> wr=
ote:
> >>>
> >>>
> >>>> 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 speci=
al
> >>>> zero page, so you implemented another THP split function to handle i=
t?
> >>>>
> >>>> Anyway the code should answer the most questions.
> >>>
> >>> They can indeed end up on both lists. This did have to be handled whe=
n
> >>> 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.
>
> I looked through these patches yesterday. There are indeed parts that are=
 very similar, but the approach
> taken seems overly complicated compared to what I have written. What=E2=
=80=99s the status of work on this since last year?

Overly complicated... which patches and how?

At a minimum, you'd need 1 & 3 from the first series and this patch:

https://lore.kernel.org/r/20220608141432.23258-1-linmiaohe@huawei.com/