ksm: add zero_pages_sharing documentation
authorxu xin <xu.xin16@zte.com.cn>
Fri, 30 Dec 2022 01:17:28 +0000 (09:17 +0800)
committerAndrew Morton <akpm@linux-foundation.org>
Fri, 10 Feb 2023 23:36:02 +0000 (15:36 -0800)
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.

Link: https://lkml.kernel.org/r/202212300917284911971@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Cc: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Documentation/admin-guide/mm/ksm.rst

index fb6ba2002a4b2aaa73e20b7203578366ff8d472a..f160f9487a90f8683ec9a57f6a5c2ebb93491269 100644 (file)
@@ -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``