From: Lance Yang ioworker0@gmail.com
mainline inclusion from mainline-v6.11-rc1 commit 9b89e018990de47c72ef8b2ca29204f88fda8f05 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IAIHPC
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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This commit introduces documentation for mTHP split counters in transhuge.rst.
[ioworker0@gmail.com: improve the doc as suggested by Ryan] Link: https://lkml.kernel.org/r/20240704012905.42971-3-ioworker0@gmail.com [ioworker0@gmail.com: tweak Documentation/admin-guide/mm/transhuge.rst] Link: https://lkml.kernel.org/r/20240707013659.1151-1-ioworker0@gmail.com Link: https://lkml.kernel.org/r/20240628130750.73097-3-ioworker0@gmail.com Signed-off-by: Mingzhe Yang mingzhe.yang@ly.com Signed-off-by: Lance Yang ioworker0@gmail.com Reviewed-by: Barry Song baohua@kernel.org Reviewed-by: Ryan Roberts ryan.roberts@arm.com Acked-by: David Hildenbrand david@redhat.com Cc: Bang Li libang.li@antgroup.com Cc: Baolin Wang baolin.wang@linux.alibaba.com Cc: Yang Shi shy828301@gmail.com Cc: Zi Yan ziy@nvidia.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- Documentation/admin-guide/mm/transhuge.rst | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst index 89e124d66ceb..13e09977c43a 100644 --- a/Documentation/admin-guide/mm/transhuge.rst +++ b/Documentation/admin-guide/mm/transhuge.rst @@ -397,10 +397,6 @@ 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 @@ -542,6 +538,21 @@ 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. + +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. + 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