diff mbox series

[mm,v2,2/9] memcg: enable accounting for kernfs nodes

Message ID 4f129690-88fe-18f2-2142-b179a804924b@openvz.org (mailing list archive)
State New
Headers show
Series memcg: accounting for objects allocated by mkdir cgroup | expand

Commit Message

Vasily Averin May 21, 2022, 4:37 p.m. UTC 
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@openvz.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
---
 fs/kernfs/mount.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Muchun Song May 22, 2022, 6:37 a.m. UTC | #1 
On Sat, May 21, 2022 at 07:37:49PM +0300, Vasily Averin wrote:
> 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@openvz.org>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>
diff mbox series

Patch

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",