Add document for newly added thp_swpout, thp_swpout_fallback fields in
/proc/vmstat.
Signed-off-by: "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: Jonathan Corbet <corbet@lwn.net>
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