From: xu xin <xu.xin16@zte.com.cn>

With the enablement of container-level KSM (e.g., via prctl [1]), there is
a growing demand for container-level observability of KSM behavior. However,
current cgroup implementations lack support for exposing KSM-related
metrics.

This patch introduces a new interface named ksm_stat
at the cgroup hierarchy level, enabling users to monitor KSM merging
statistics specifically for containers where this feature has been
activated, eliminating the need to manually inspect KSM information for
each individual process within the cgroup.

Users can obtain the KSM information of a cgroup just by:

# cat /sys/fs/cgroup/memory.ksm_stat
ksm_rmap_items 76800
ksm_zero_pages 0
ksm_merging_pages 76800
ksm_process_profit 309657600

Current implementation supports cgroup v1 temporarily; cgroup v2
compatibility is planned for future versions.


xu xin (6):
  memcontrol: rename mem_cgroup_scan_tasks()
  memcontrol: introduce the new mem_cgroup_scan_tasks()
  memcontrol-v1: introduce ksm_stat at cgroup level
  memcontrol-v1: add ksm_zero_pages in cgroup/memory.ksm_stat
  memcontrol-v1: add ksm_merging_pages in cgroup/memory.ksm_stat
  memcontrol-v1: add ksm_profit in cgroup/memory.ksm_stat

 include/linux/memcontrol.h |  7 +++++
 mm/memcontrol-v1.c         | 55 ++++++++++++++++++++++++++++++++++++++
 mm/memcontrol.c            | 28 +++++++++++++++++--
 mm/oom_kill.c              |  6 ++---
 4 files changed, 91 insertions(+), 5 deletions(-)

-- 
2.39.3

On 22.04.25 13:14, xu.xin16@zte.com.cn wrote:
> From: xu xin <xu.xin16@zte.com.cn>
> 
> With the enablement of container-level KSM (e.g., via prctl [1]), there is
> a growing demand for container-level observability of KSM behavior. However,
> current cgroup implementations lack support for exposing KSM-related
> metrics.
> 
> This patch introduces a new interface named ksm_stat
> at the cgroup hierarchy level, enabling users to monitor KSM merging
> statistics specifically for containers where this feature has been
> activated, eliminating the need to manually inspect KSM information for
> each individual process within the cgroup.
> 
> Users can obtain the KSM information of a cgroup just by:
> 
> # cat /sys/fs/cgroup/memory.ksm_stat
> ksm_rmap_items 76800
> ksm_zero_pages 0
> ksm_merging_pages 76800
> ksm_process_profit 309657600
> 
> Current implementation supports cgroup v1 temporarily; cgroup v2
> compatibility is planned for future versions.

As raised by Willy, we focus on v2.

Independent of that, I strongly assume that 
Documentation/admin-guide/cgroup-v1/memory.rst needs care :)

-- 
Cheers,

David / dhildenb