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Subject[PATCH v4 5/6] ksm: add zero pages sharing documentation
From: xu xin <>

When enabling use_zero_pages, pages_sharing cannot represent how
much memory saved indeed. zero_pages_sharing + pages_sharing does.
add the description of zero_pages_sharing.

Cc: Xiaokai Ran <>
Cc: Yang Yang <>
Cc: Jiang Xuexin <>
Cc: Claudio Imbrenda <>
Cc: David Hildenbrand <>
Signed-off-by: xu xin <>
Documentation/admin-guide/mm/ksm.rst | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index fb6ba2002a4b..f160f9487a90 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -173,6 +173,13 @@ stable_node_chains
the number of KSM pages that hit the ``max_page_sharing`` limit
number of duplicated KSM pages
+ how many empty pages are sharing kernel zero page(s) instead of
+ with each other as it would happen normally. Only effective when
+ enabling ``use_zero_pages`` knob.
+When enabling ``use_zero_pages``, the sum of ``pages_sharing`` +
+``zero_pages_sharing`` represents how much really saved by KSM.

A high ratio of ``pages_sharing`` to ``pages_shared`` indicates good
sharing, but a high ratio of ``pages_unshared`` to ``pages_sharing``
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