Re: [PATCH v2 1/2] mm: memcontrol: use memcg_kmem_enabled in count_objcg_event

Roman Gushchin
2022-09-20T02:27:38Z

On Tue, Sep 20, 2022 at 02:06:33AM +0800, Kairui Song wrote:
> From: Kairui Song <kasong-1Nz4purKYjRBDgjK7y7TUQ@public.gmane.org>
>
> There are currently two helpers for checking if cgroup kmem
> accounting is enabled:
>
> - mem_cgroup_kmem_disabled
> - memcg_kmem_enabled
>
> mem_cgroup_kmem_disabled is a simple helper that returns true
> if cgroup.memory=nokmem is specified, otherwise returns false.
>
> memcg_kmem_enabled is a bit different, it returns true if
> cgroup.memory=nokmem is not specified and there was at least one
> non-root memory control enabled cgroup ever created. This help improve
> performance when kmem accounting was not actually activated. And it's
> optimized with static branch.
>
> The usage of mem_cgroup_kmem_disabled is for sub-systems that need to
> preallocate data for kmem accounting since they could be initialized
> before kmem accounting is activated. But count_objcg_event doesn't
> need that, so using memcg_kmem_enabled is better here.
>
> Signed-off-by: Kairui Song <kasong-1Nz4purKYjRBDgjK7y7TUQ@public.gmane.org>

Acked-by: Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>

Thanks, Kairui!