134 lines
3.3 KiB
ReStructuredText
134 lines
3.3 KiB
ReStructuredText
|
==========================
|
||
|
|
Shrinker Debugfs Interface
|
||
|
|
==========================
|
||
|
|
|
||
|
|
Shrinker debugfs interface provides a visibility into the kernel memory
|
||
|
|
shrinkers subsystem and allows to get information about individual shrinkers
|
||
|
|
and interact with them.
|
||
|
|
|
||
|
|
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 **count** and **scan** files, which allow to
|
||
|
|
trigger *count_objects()* and *scan_objects()* callbacks 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 scan
|
||
|
|
|
||
|
|
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
|
||
|
|
|
||
|
|
4. *Scan objects*
|
||
|
|
|
||
|
|
The expected input format::
|
||
|
|
|
||
|
|
<cgroup inode id> <numa id> <number of objects to scan>
|
||
|
|
|
||
|
|
For a non-memcg-aware shrinker or on a system with no memory
|
||
|
|
cgrups **0** should be passed as cgroup id.
|
||
|
|
::
|
||
|
|
|
||
|
|
$ cd /sys/kernel/debug/shrinker/
|
||
|
|
$ cd sb-btrfs\:vda2-24/
|
||
|
|
|
||
|
|
$ cat count | head -n 5
|
||
|
|
1 212 0
|
||
|
|
21 97 0
|
||
|
|
55 802 5
|
||
|
|
2367 2 0
|
||
|
|
225 13 0
|
||
|
|
|
||
|
|
$ echo "55 0 200" > scan
|
||
|
|
|
||
|
|
$ cat count | head -n 5
|
||
|
|
1 212 0
|
||
|
|
21 96 0
|
||
|
|
55 752 5
|
||
|
|
2367 2 0
|
||
|
|
225 13 0
|