[PATCH] doc: add information about max_ptes_swap

[Ebru Akagunduz]

max_ptes_swap specifies how many pages can be brought in from
swap when collapsing a group of pages into a transparent huge page.

/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap

A higher value can cause excessive swap IO and waste
memory. A lower value can prevent THPs from being
collapsed, resulting fewer pages being collapsed into
THPs, and lower memory access performance.

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx>
---
 Documentation/vm/transhuge.txt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 8143b9e..8a28268 100644
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -170,6 +170,16 @@ A lower value leads to gain less thp performance. Value of
 max_ptes_none can waste cpu time very little, you can
 ignore it.
 
+max_ptes_swap specifies how many pages can be brought in from
+swap when collapsing a group of pages into a transparent huge page.
+
+/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap
+
+A higher value can cause excessive swap IO and waste
+memory. A lower value can prevent THPs from being
+collapsed, resulting fewer pages being collapsed into
+THPs, and lower memory access performance.
+
 == Boot parameter ==
 
 You can change the sysfs boot time defaults of Transparent Hugepage
-- 
1.9.1

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