From 94bfe85bde18a99612bb5d0ce348643c2d352836 Mon Sep 17 00:00:00 2001
From: Yang Yang <yang.yang29@zte.com.cn>
Date: Thu, 28 Apr 2022 23:16:16 -0700
Subject: mm/vmstat: add events for ksm cow

Users may use ksm by calling madvise(, , MADV_MERGEABLE) when they want to
save memory, it's a tradeoff by suffering delay on ksm cow.  Users can get
to know how much memory ksm saved by reading
/sys/kernel/mm/ksm/pages_sharing, but they don't know what's the costs of
ksm cow, and this is important of some delay sensitive tasks.

So add ksm cow events to help users evaluate whether or how to use ksm.
Also update Documentation/admin-guide/mm/ksm.rst with new added events.

Link: https://lkml.kernel.org/r/20220331035616.2390805-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Saravanan D <saravanand@fb.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/vmstat.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'mm/vmstat.c')

diff --git a/mm/vmstat.c b/mm/vmstat.c
index f2d0dec1062d..b94a2e4723ff 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1393,6 +1393,9 @@ const char * const vmstat_text[] = {
 	"ksm_swpin_copy",
 #endif
 #endif
+#ifdef CONFIG_KSM
+	"cow_ksm",
+#endif
 #ifdef CONFIG_X86
 	"direct_map_level2_splits",
 	"direct_map_level3_splits",
-- 
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