doc: add information about max_ptes_none

max_ptes_none specifies how many extra small pages (that are
not already mapped) can be allocated when collapsing a group
of small pages into one large page.

/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none

A higher value leads to use additional memory for programs.
A lower value leads to gain less thp performance. Value of
max_ptes_none can waste cpu time very little, you can
ignore it.

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 6b31cfbe2a9a1197b8d33d294e90bd6f64d3fcd9..8143b9e8373db41746330c468dede07acfd96b56 100644 (file)
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -159,6 +159,17 @@ for each pass:
 
 /sys/kernel/mm/transparent_hugepage/khugepaged/full_scans
 
+max_ptes_none specifies how many extra small pages (that are
+not already mapped) can be allocated when collapsing a group
+of small pages into one large page.
+
+/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none
+
+A higher value leads to use additional memory for programs.
+A lower value leads to gain less thp performance. Value of
+max_ptes_none can waste cpu time very little, you can
+ignore it.
+
 == Boot parameter ==
 
 You can change the sysfs boot time defaults of Transparent Hugepage