kernfs nodes are quite small kernel objects, however there are few
scenarios where it consumes significant piece of all allocated memory:
1) creating a new netdevice allocates ~50Kb of memory, where ~10Kb
was allocated for 80+ kernfs nodes.
2) cgroupv2 mkdir allocates ~60Kb of memory, ~10Kb of them are kernfs
structures.
3) Shakeel Butt reports that Google has workloads which create 100s
of subcontainers and they have observed high system overhead
without memcg accounting of kernfs.
Usually new kernfs node creates few other objects:
Allocs Alloc Allocation
number size
--------------------------------------------
1 + 128 (__kernfs_new_node+0x4d) kernfs node
1 + 88 (__kernfs_iattrs+0x57) kernfs iattrs
1 + 96 (simple_xattr_alloc+0x28) simple_xattr, can grow over 4Kb
1 32 (simple_xattr_set+0x59)
1 8 (__kernfs_new_node+0x30)
'+' -- to be accounted
This patch enables accounting for kernfs nodes slab cache.
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>
Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
fs/kernfs/mount.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index cfa79715fc1a..3ac4191b1c40 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -391,7 +391,8 @@ void __init kernfs_init(void)
{
kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
sizeof(struct kernfs_node),
- 0, SLAB_PANIC, NULL);
+ 0, SLAB_PANIC | SLAB_ACCOUNT,
+ NULL);
/* Creates slab cache for kernfs inode attributes */
kernfs_iattrs_cache = kmem_cache_create("kernfs_iattrs_cache",
--
2.36.1
