The patch titled
Subject: mm: add docs for per-order mTHP split counters
has been added to the -mm mm-unstable branch. Its filename is
mm-add-docs-for-per-order-mthp-split-counters.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-docs-for-per-order-mthp-split-counters.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lance Yang <ioworker0@xxxxxxxxx>
Subject: mm: add docs for per-order mTHP split counters
Date: Fri, 28 Jun 2024 21:07:50 +0800
This commit introduces documentation for mTHP split counters in
transhuge.rst.
Link: https://lkml.kernel.org/r/20240628130750.73097-3-ioworker0@xxxxxxxxx
Signed-off-by: Mingzhe Yang <mingzhe.yang@xxxxxx>
Signed-off-by: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Bang Li <libang.li@xxxxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/transhuge.rst | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/Documentation/admin-guide/mm/transhuge.rst~mm-add-docs-for-per-order-mthp-split-counters
+++ a/Documentation/admin-guide/mm/transhuge.rst
@@ -514,6 +514,22 @@ 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
+ base pages. 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.
+
As the system ages, allocating huge pages may be expensive as the
system uses memory compaction to copy data around memory to free a
huge page for use. There are some counters in ``/proc/vmstat`` to help
_
Patches currently in -mm which might be from ioworker0@xxxxxxxxx are
mm-add-per-order-mthp-split-counters.patch
mm-add-docs-for-per-order-mthp-split-counters.patch
