Re: [PATCH v2 0/9] support ksm_stat showing at cgroup level

[Shakeel Butt <shakeel.butt@linux.dev>]

On Thu, May 01, 2025 at 12:08:54PM +0800, 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 both cgroup v2 and cgroup v1.
> 

Before adding these stats to memcg, add global stats for them in
enum node_stat_item and then you can expose them in memcg through
memory.stat instead of a new interface.