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

[Huang, Ying]

Barry Song <21cnbao@xxxxxxxxx> writes:

> From: Barry Song <v-songbaohua@xxxxxxxx>
>
> 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@xxxxxxxx>
> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Chris Li <chrisl@xxxxxxxxxx>
> Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Cc: Kairui Song <kasong@xxxxxxxxxxx>
> Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
> Cc: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
> Cc: Usama Arif <usamaarif642@xxxxxxxxx>
> ---
>  -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@xxxxxxxxx>
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?

[snip]

--
Best Regards,
Huang, Ying