The patch titled
Subject: mm: docs: document shrinker debugfs
has been added to the -mm mm-unstable branch. Its filename is
mm-docs-document-shrinker-debugfs.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-docs-document-shrinker-debugfs.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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------------------------------------------------------
From: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Subject: mm: docs: document shrinker debugfs
Date: Tue, 31 May 2022 20:22:25 -0700
Add a document describing the shrinker debugfs interface.
Link: https://lkml.kernel.org/r/20220601032227.4076670-5-roman.gushchin@xxxxxxxxx
Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/index.rst | 1
Documentation/admin-guide/mm/shrinker_debugfs.rst | 104 ++++++++++++
2 files changed, 105 insertions(+)
--- a/Documentation/admin-guide/mm/index.rst~mm-docs-document-shrinker-debugfs
+++ a/Documentation/admin-guide/mm/index.rst
@@ -36,6 +36,7 @@ the Linux memory management.
numa_memory_policy
numaperf
pagemap
+ shrinker_debugfs
soft-dirty
swap_numa
transhuge
--- /dev/null
+++ a/Documentation/admin-guide/mm/shrinker_debugfs.rst
@@ -0,0 +1,104 @@
+.. _shrinker_debugfs:
+
+==========================
+Shrinker Debugfs Interface
+==========================
+
+Shrinker debugfs interface provides a visibility into the kernel memory
+shrinkers subsystem and allows to get information about individual shrinkers.
+
+For each shrinker registered in the system a directory in **<debugfs>/shrinker/**
+is created. The directory's name is composed from the shrinker's name and an
+unique id: e.g. *kfree_rcu-0* or *sb-xfs:vda1-36*.
+
+Each shrinker directory contains the **count** file, which allows to trigger
+the *count_objects()* callback for each memcg and numa node (if applicable).
+
+Usage:
+------
+
+1. *List registered shrinkers*
+
+ ::
+
+ $ cd /sys/kernel/debug/shrinker/
+ $ ls
+ dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42
+ mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43
+ mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44
+ rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49
+ sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13
+ sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36
+ sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19
+ sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10
+ sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9
+ sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37
+ sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38
+ sb-dax-11 sb-proc-45 sb-tmpfs-35
+ sb-debugfs-7 sb-proc-46 sb-tmpfs-40
+
+2. *Get information about a specific shrinker*
+
+ ::
+
+ $ cd sb-btrfs\:vda2-24/
+ $ ls
+ count
+
+3. *Count objects*
+
+ Each line in the output has the following format::
+
+ <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1> ...
+ <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1> ...
+ ...
+
+ If there are no objects on all numa nodes, a line is omitted. If there
+ are no objects at all, the output might be empty.
+
+ If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed
+ as cgroup inode id. If the shrinker is not numa-aware, 0's are printed
+ for all nodes except the first one.
+ ::
+
+ $ cat count
+ 1 224 2
+ 21 98 0
+ 55 818 10
+ 2367 2 0
+ 2401 30 0
+ 225 13 0
+ 599 35 0
+ 939 124 0
+ 1041 3 0
+ 1075 1 0
+ 1109 1 0
+ 1279 60 0
+ 1313 7 0
+ 1347 39 0
+ 1381 3 0
+ 1449 14 0
+ 1483 63 0
+ 1517 53 0
+ 1551 6 0
+ 1585 1 0
+ 1619 6 0
+ 1653 40 0
+ 1687 11 0
+ 1721 8 0
+ 1755 4 0
+ 1789 52 0
+ 1823 888 0
+ 1857 1 0
+ 1925 2 0
+ 1959 32 0
+ 2027 22 0
+ 2061 9 0
+ 2469 799 0
+ 2537 861 0
+ 2639 1 0
+ 2707 70 0
+ 2775 4 0
+ 2877 84 0
+ 293 1 0
+ 735 8 0
_
Patches currently in -mm which might be from roman.gushchin@xxxxxxxxx are
mm-memcontrol-introduce-mem_cgroup_ino-and-mem_cgroup_get_from_ino.patch
mm-shrinkers-introduce-debugfs-interface-for-memory-shrinkers.patch
mm-shrinkers-provide-shrinkers-with-names.patch
mm-docs-document-shrinker-debugfs.patch
tools-add-memcg_shrinkerpy.patch
mm-shrinkers-add-scan-interface-for-shrinker-debugfs.patch
