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Message-ID: <fe3ccab5-25bc-4cd3-9628-60fe6e8e3cf5@redhat.com>
Date: Fri, 5 Jul 2024 11:09:51 +0200
From: David Hildenbrand <david@...hat.com>
To: Lance Yang <ioworker0@...il.com>, akpm@...ux-foundation.org
Cc: dj456119@...il.com, 21cnbao@...il.com, ryan.roberts@....com,
shy828301@...il.com, ziy@...dia.com, libang.li@...group.com,
baolin.wang@...ux.alibaba.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Barry Song <baohua@...nel.org>,
Mingzhe Yang <mingzhe.yang@...com>
Subject: Re: [PATCH v3 2/2] mm: add docs for per-order mTHP split counters
On 04.07.24 03:29, Lance Yang wrote:
> This commit introduces documentation for mTHP split counters in
> transhuge.rst.
>
> Reviewed-by: Barry Song <baohua@...nel.org>
> Signed-off-by: Mingzhe Yang <mingzhe.yang@...com>
> Signed-off-by: Lance Yang <ioworker0@...il.com>
> ---
> Documentation/admin-guide/mm/transhuge.rst | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
> index 1f72b00af5d3..0830aa173a8b 100644
> --- a/Documentation/admin-guide/mm/transhuge.rst
> +++ b/Documentation/admin-guide/mm/transhuge.rst
> @@ -369,10 +369,6 @@ also applies to the regions registered in khugepaged.
> Monitoring usage
> ================
>
> -.. note::
> - Currently the below counters only record events relating to
> - PMD-sized THP. Events relating to other THP sizes are not included.
> -
> The number of PMD-sized anonymous transparent huge pages currently used by the
> system is available by reading the AnonHugePages field in ``/proc/meminfo``.
> To identify what applications are using PMD-sized anonymous transparent huge
> @@ -514,6 +510,22 @@ file_fallback_charge
> falls back to using small pages even though the allocation was
> successful.
>
> +split
> + is incremented every time a huge page is successfully split into
> + smaller orders. This can happen for a variety of reasons but a
> + common reason is that a huge page is old and is being reclaimed.
> + This action implies splitting any block mappings into PTEs.
> +
> +split_failed
> + is incremented if kernel fails to split huge
> + page. This can happen if the page was pinned by somebody.
> +
> +split_deferred
> + is incremented when a huge page is put onto split
> + queue. This happens when a huge page is partially unmapped and
> + splitting it would free up some memory. Pages on split queue are
> + going to be split under memory pressure.
".. if splitting is possible." ;)
Acked-by: David Hildenbrand <david@...hat.com>
--
Cheers,
David / dhildenb
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