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Commit 8d420f6c authored by Huang Ying's avatar Huang Ying Committed by Jonathan Corbet
Browse files

mm, THP, doc: Add document for thp_swpout/thp_swpout_fallback 



Add document for newly added thp_swpout, thp_swpout_fallback fields in
/proc/vmstat.

Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 9167b942

Documentation/vm/transhuge.rst

+9 −0
Original line number Diff line number Diff line
@@ -355,6 +355,15 @@ thp_zero_page_alloc_failed 
	is incremented if kernel fails to allocate

	huge zero page and falls back to using small pages.



thp_swpout

	is incremented every time a huge page is swapout in one

	piece without splitting.



thp_swpout_fallback

	is incremented if a huge page has to be split before swapout.

	Usually because failed to allocate some continuous swap space

	for the huge page.



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