From 8d420f6c27c530e25c057a59575e193dd62bb743 Mon Sep 17 00:00:00 2001 From: Huang Ying <ying.huang@intel.com> Date: Wed, 9 May 2018 16:23:41 +0800 Subject: [PATCH] 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: "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> --- Documentation/vm/transhuge.rst | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/vm/transhuge.rst b/Documentation/vm/transhuge.rst index 569d182cc9738..2c6867fca6ffd 100644 --- a/Documentation/vm/transhuge.rst +++ b/Documentation/vm/transhuge.rst @@ -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 -- GitLab