Re: [PATCH v6 15/19] mm: memcg/slab: deprecate slab_root_caches

Shakeel Butt
2020-06-22T17:36:37Z

On Mon, Jun 8, 2020 at 4:07 PM Roman Gushchin <guro@fb.com> wrote:
>
> Currently there are two lists of kmem_caches:
> 1) slab_caches, which contains all kmem_caches,
> 2) slab_root_caches, which contains only root kmem_caches.
>
> And there is some preprocessor magic to have a single list
> if CONFIG_MEMCG_KMEM isn't enabled.
>
> It was required earlier because the number of non-root kmem_caches
> was proportional to the number of memory cgroups and could reach
> really big values. Now, when it cannot exceed the number of root
> kmem_caches, there is really no reason to maintain two lists.
>
> We never iterate over the slab_root_caches list on any hot paths,
> so it's perfectly fine to iterate over slab_caches and filter out
> non-root kmem_caches.
>
> It allows to remove a lot of config-dependent code and two pointers
> from the kmem_cache structure.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Shakeel Butt <shakeelb@google.com>