The patch titled
Subject: proc/ksm: add ksm stats to /proc/pid/smaps
has been added to the -mm mm-unstable branch. Its filename is
proc-ksm-add-ksm-stats-to-proc-pid-smaps.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/proc-ksm-add-ksm-stats-to-proc-pid-smaps.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: proc/ksm: add ksm stats to /proc/pid/smaps
Date: Fri, 11 Aug 2023 09:28:03 -0700
With madvise and prctl KSM can be enabled for different VMA's. Once it is
enabled we can query how effective KSM is overall. However we cannot
easily query if an individual VMA benefits from KSM.
This commit adds a KSM section to the /prod/<pid>/smaps file. It reports
how many of the pages are KSM pages.
Here is a typical output:
7f420a000000-7f421a000000 rw-p 00000000 00:00 0
Size: 262144 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Rss: 51212 kB
Pss: 8276 kB
Shared_Clean: 172 kB
Shared_Dirty: 42996 kB
Private_Clean: 196 kB
Private_Dirty: 7848 kB
Referenced: 15388 kB
Anonymous: 51212 kB
KSM: 41376 kB
LazyFree: 0 kB
AnonHugePages: 0 kB
ShmemPmdMapped: 0 kB
FilePmdMapped: 0 kB
Shared_Hugetlb: 0 kB
Private_Hugetlb: 0 kB
Swap: 202016 kB
SwapPss: 3882 kB
Locked: 0 kB
THPeligible: 0
ProtectionKey: 0
ksm_state: 0
ksm_skip_base: 0
ksm_skip_count: 0
VmFlags: rd wr mr mw me nr mg anon
This information also helps with the following workflow:
- First enable KSM for all the VMA's of a process with prctl.
- Then analyze with the above smaps report which VMA's benefit the most
- Change the application (if possible) to add the corresponding madvise
calls for the VMA's that benefit the most
Link: https://lkml.kernel.org/r/20230811162803.1361989-1-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.rst | 3 +++
fs/proc/task_mmu.c | 5 +++++
2 files changed, 8 insertions(+)
--- a/Documentation/filesystems/proc.rst~proc-ksm-add-ksm-stats-to-proc-pid-smaps
+++ a/Documentation/filesystems/proc.rst
@@ -461,6 +461,7 @@ Memory Area, or VMA) there is a series o
Private_Dirty: 0 kB
Referenced: 892 kB
Anonymous: 0 kB
+ KSM: 0 kB
LazyFree: 0 kB
AnonHugePages: 0 kB
ShmemPmdMapped: 0 kB
@@ -501,6 +502,8 @@ accessed.
a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
and a page is modified, the file page is replaced by a private anonymous copy.
+"KSM" shows the amount of anonymous memory that has been de-duplicated.
+
"LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
The memory isn't freed immediately with madvise(). It's freed in memory
pressure if the memory is clean. Please note that the printed value might
--- a/fs/proc/task_mmu.c~proc-ksm-add-ksm-stats-to-proc-pid-smaps
+++ a/fs/proc/task_mmu.c
@@ -396,6 +396,7 @@ struct mem_size_stats {
unsigned long swap;
unsigned long shared_hugetlb;
unsigned long private_hugetlb;
+ unsigned long ksm;
u64 pss;
u64 pss_anon;
u64 pss_file;
@@ -452,6 +453,9 @@ static void smaps_account(struct mem_siz
mss->lazyfree += size;
}
+ if (PageKsm(page))
+ mss->ksm += size;
+
mss->resident += size;
/* Accumulate the size in pages that have been accessed. */
if (young || page_is_young(page) || PageReferenced(page))
@@ -822,6 +826,7 @@ static void __show_smap(struct seq_file
SEQ_PUT_DEC(" kB\nPrivate_Dirty: ", mss->private_dirty);
SEQ_PUT_DEC(" kB\nReferenced: ", mss->referenced);
SEQ_PUT_DEC(" kB\nAnonymous: ", mss->anonymous);
+ SEQ_PUT_DEC(" kB\nKSM: ", mss->ksm);
SEQ_PUT_DEC(" kB\nLazyFree: ", mss->lazyfree);
SEQ_PUT_DEC(" kB\nAnonHugePages: ", mss->anonymous_thp);
SEQ_PUT_DEC(" kB\nShmemPmdMapped: ", mss->shmem_thp);
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
proc-ksm-add-ksm-stats-to-proc-pid-smaps.patch
