linux-kernel - [PATCH v4 5/6] ksm: add zero_pages

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Date:   Mon, 26 Dec 2022 10:07:12 +0800 (CST)
From:   <yang.yang29@....com.cn>
To:     <akpm@...ux-foundation.org>
Cc:     <david@...hat.com>, <imbrenda@...ux.ibm.com>,
        <jiang.xuexin@....com.cn>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <ran.xiaokai@....com.cn>,
        <xu.xin.sc@...il.com>, <xu.xin16@....com.cn>,
        <yang.yang29@....com.cn>
Subject: [PATCH v4 5/6] ksm: add zero_pages_sharing documentation

From: xu xin <xu.xin16@....com.cn>

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 <ran.xiaokai@....com.cn>
Cc: Yang Yang <yang.yang29@....com.cn>
Cc: Jiang Xuexin <jiang.xuexin@....com.cn>
Cc: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: David Hildenbrand <david@...hat.com>
Signed-off-by: xu xin <xu.xin16@....com.cn>
---
 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
 stable_node_dups
         number of duplicated KSM pages
+zero_pages_sharing
+        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``
-- 
2.15.2