The patch titled
Subject: mm/vmstat: add event for ksm swapping in copy
has been added to the -mm tree. Its filename is
mm-vmstat-add-event-for-ksm-swapping-in-copy.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-vmstat-add-event-for-ksm-swapping-in-copy.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmstat-add-event-for-ksm-swapping-in-copy.patch
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------------------------------------------------------
From: Yang Yang <yang.yang29@xxxxxxxxxx>
Subject: mm/vmstat: add event for ksm swapping in copy
When faults in from swap what used to be a KSM page and that page had been
swapped in before, system has to make a copy, and leaves remerging the
pages to a later pass of ksmd.
That is not good for performace, we'd better to reduce this kind of copy.
There are some ways to reduce it, for example lessen swappiness or
madvise(, , MADV_MERGEABLE) range. So add this event to support doing
this tuning. Just like this patch: "mm, THP, swap: add THP swapping out
fallback counting".
Link: https://lkml.kernel.org/r/20220113023839.758845-1-yang.yang29@xxxxxxxxxx
Signed-off-by: Yang Yang <yang.yang29@xxxxxxxxxx>
Reviewed-by: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Saravanan D <saravanand@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/vm_event_item.h | 3 +++
mm/ksm.c | 3 +++
mm/vmstat.c | 3 +++
3 files changed, 9 insertions(+)
--- a/include/linux/vm_event_item.h~mm-vmstat-add-event-for-ksm-swapping-in-copy
+++ a/include/linux/vm_event_item.h
@@ -129,6 +129,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
#ifdef CONFIG_SWAP
SWAP_RA,
SWAP_RA_HIT,
+#ifdef CONFIG_KSM
+ KSM_SWPIN_COPY,
+#endif
#endif
#ifdef CONFIG_X86
DIRECT_MAP_LEVEL2_SPLIT,
--- a/mm/ksm.c~mm-vmstat-add-event-for-ksm-swapping-in-copy
+++ a/mm/ksm.c
@@ -2595,6 +2595,9 @@ struct page *ksm_might_need_to_copy(stru
SetPageDirty(new_page);
__SetPageUptodate(new_page);
__SetPageLocked(new_page);
+#ifdef CONFIG_SWAP
+ count_vm_event(KSM_SWPIN_COPY);
+#endif
}
return new_page;
--- a/mm/vmstat.c~mm-vmstat-add-event-for-ksm-swapping-in-copy
+++ a/mm/vmstat.c
@@ -1385,6 +1385,9 @@ const char * const vmstat_text[] = {
#ifdef CONFIG_SWAP
"swap_ra",
"swap_ra_hit",
+#ifdef CONFIG_KSM
+ "ksm_swpin_copy",
+#endif
#endif
#ifdef CONFIG_X86
"direct_map_level2_splits",
_
Patches currently in -mm which might be from yang.yang29@xxxxxxxxxx are
mm-vmstat-add-event-for-ksm-swapping-in-copy.patch
