Re: [PATCH] mm: memcontrol: rename memcg_kmem_enabled()

[Michal Hocko]

On Mon 13-02-23 11:29:22, Roman Gushchin wrote:
> Currently there are two kmem-related helper functions with a confusing
> semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled().
> 
> The problem is that an obvious expectation
> memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(),
> can be false.
> 
> mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it
> returns true only if CONFIG_MEMCG_KMEM is not set or the kmem
> accounting is disabled using a boot time kernel option
> "cgroup.memory=nokmem". It never changes the value dynamically.
> 
> memcg_kmem_enabled() is different: it always returns false until
> the first non-root memory cgroup will get online (assuming the kernel
> memory accounting is enabled). It's goal is to improve the performance
> on systems without the cgroupfs mounted/memory controller enabled or
> on the systems with only the root memory cgroup.
> 
> To make things more obvious and avoid potential bugs, let's rename
> memcg_kmem_enabled() to memcg_kmem_online().
> 
> Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
> Cc: Muchun Song <muchun.song@xxxxxxxxx>
> Cc: Dennis Zhou <dennis@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx

Makes sense
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks!

-- 
Michal Hocko
SUSE Labs