linux-kernel - Re: [PATCH v3] mm: add per-order mTHP swpin counters

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Message-ID: <87zfmk8yro.fsf@yhuang6-desk2.ccr.corp.intel.com>
Date: Thu, 31 Oct 2024 16:25:31 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Barry Song <21cnbao@...il.com>
Cc: akpm@...ux-foundation.org,  linux-mm@...ck.org,
  linux-kernel@...r.kernel.org,  Barry Song <v-songbaohua@...o.com>,
  Baolin Wang <baolin.wang@...ux.alibaba.com>,  David Hildenbrand
 <david@...hat.com>,  Chris Li <chrisl@...nel.org>,  Yosry Ahmed
 <yosryahmed@...gle.com>,  Kairui Song <kasong@...cent.com>,  Ryan Roberts
 <ryan.roberts@....com>,  Kanchana P Sridhar
 <kanchana.p.sridhar@...el.com>,  Usama Arif <usamaarif642@...il.com>
Subject: Re: [PATCH v3] mm: add per-order mTHP swpin counters

Barry Song <21cnbao@...il.com> writes:

> On Thu, Oct 31, 2024 at 9:09 PM Huang, Ying <ying.huang@...el.com> wrote:
>>
>> Barry Song <21cnbao@...il.com> writes:
>>
>> > From: Barry Song <v-songbaohua@...o.com>
>> >
>> > This helps profile the sizes of folios being swapped in. Currently,
>> > only mTHP swap-out is being counted.
>> > The new interface can be found at:
>> > /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats/swpin
>> > For example,
>> > $ cat /sys/kernel/mm/transparent_hugepage/hugepages-64kB/stats/swpin
>> > 12809
>> > $ cat /sys/kernel/mm/transparent_hugepage/hugepages-32kB/stats/swpin
>> > 4763
>> >
>> > Signed-off-by: Barry Song <v-songbaohua@...o.com>
>> > Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> > Acked-by: David Hildenbrand <david@...hat.com>
>> > Cc: Chris Li <chrisl@...nel.org>
>> > Cc: Yosry Ahmed <yosryahmed@...gle.com>
>> > Cc: "Huang, Ying" <ying.huang@...el.com>
>> > Cc: Kairui Song <kasong@...cent.com>
>> > Cc: Ryan Roberts <ryan.roberts@....com>
>> > Cc: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
>> > Cc: Usama Arif <usamaarif642@...il.com>
>> > ---
>> >  -v3: minor refine changelog per Huang, Ying. thanks!
>> >
>> >  Documentation/admin-guide/mm/transhuge.rst | 4 ++++
>> >  include/linux/huge_mm.h                    | 1 +
>> >  mm/huge_memory.c                           | 3 +++
>> >  mm/page_io.c                               | 3 +++
>> >  4 files changed, 11 insertions(+)
>> >
>> > diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
>> > index 2a171ed5206e..5caa3fb2feb1 100644
>> > --- a/Documentation/admin-guide/mm/transhuge.rst
>> > +++ b/Documentation/admin-guide/mm/transhuge.rst
>> > @@ -534,6 +534,10 @@ zswpout
>> >       is incremented every time a huge page is swapped out to zswap in one
>> >       piece without splitting.
>> >
>> > +swpin
>> > +     is incremented every time a huge page is swapped in from a non-zswap
>> > +     swap device in one piece.
>> > +
>> >  swpout
>> >       is incremented every time a huge page is swapped out to a non-zswap
>> >       swap device in one piece without splitting.
>>
>> In Documentation/ABI/testing/sysfs-kernel-mm-transparent-hugepage, I
>> found
>>
>> "
>> What:           /sys/kernel/mm/transparent_hugepage/
>> Date:           April 2024
>> Contact:        Linux memory management mailing list <linux-mm@...ck.org>
>> Description:
>>                 /sys/kernel/mm/transparent_hugepage/ contains a number of files and
>>                 subdirectories,
>>
>>                         - defrag
>>                         - enabled
>>                         - hpage_pmd_size
>>                         - khugepaged
>>                         - shmem_enabled
>>                         - use_zero_page
>>                         - subdirectories of the form hugepages-<size>kB, where <size>
>>                           is the page size of the hugepages supported by the kernel/CPU
>>                           combination.
>>
>>                 See Documentation/admin-guide/mm/transhuge.rst for details.
>> "
>>
>> So, Documentation/admin-guide/mm/transhuge.rst will be used as ABI
>> document?
>
> Yes. this follows:
>
> sysfs-kernel-mm-hugepages:              See
> Documentation/admin-guide/mm/hugetlbpage.rst for details.
> sysfs-kernel-mm-ksm:            See Documentation/mm/ksm.rst for more
> information.
> sysfs-kernel-mm-transparent-hugepage:           See
> Documentation/admin-guide/mm/transhuge.rst for details.
>

Got it!  Thanks!  Feel free to add

Acked-by: "Huang, Ying" <ying.huang@...el.com>

in the future versions.

--
Best Regards,
Huang, Ying