[Devel] Re: [PATCH v5 11/18] sl[au]b: Allocate objects from memcg cache

[JoonSoo Kim]

Hi, Glauber.

2012/10/19 Glauber Costa <glommer at parallels.com>:
> We are able to match a cache allocation to a particular memcg.  If the
> task doesn't change groups during the allocation itself - a rare event,
> this will give us a good picture about who is the first group to touch a
> cache page.
>
> This patch uses the now available infrastructure by calling
> memcg_kmem_get_cache() before all the cache allocations.
>
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> CC: Christoph Lameter <cl at linux.com>
> CC: Pekka Enberg <penberg at cs.helsinki.fi>
> CC: Michal Hocko <mhocko at suse.cz>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> CC: Johannes Weiner <hannes at cmpxchg.org>
> CC: Suleiman Souhlal <suleiman at google.com>
> CC: Tejun Heo <tj at kernel.org>
> ---
>  include/linux/slub_def.h | 15 ++++++++++-----
>  mm/memcontrol.c          |  3 +++
>  mm/slab.c                |  6 +++++-
>  mm/slub.c                |  5 +++--
>  4 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
> index 961e72e..ed330df 100644
> --- a/include/linux/slub_def.h
> +++ b/include/linux/slub_def.h
> @@ -13,6 +13,8 @@
>  #include <linux/kobject.h>
>
>  #include <linux/kmemleak.h>
> +#include <linux/memcontrol.h>
> +#include <linux/mm.h>
>
>  enum stat_item {
>         ALLOC_FASTPATH,         /* Allocation from cpu slab */
> @@ -209,14 +211,14 @@ static __always_inline int kmalloc_index(size_t size)
>   * This ought to end up with a global pointer to the right cache
>   * in kmalloc_caches.
>   */
> -static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
> +static __always_inline struct kmem_cache *kmalloc_slab(gfp_t flags, size_t size)
>  {
>         int index = kmalloc_index(size);
>
>         if (index == 0)
>                 return NULL;
>
> -       return kmalloc_caches[index];
> +       return memcg_kmem_get_cache(kmalloc_caches[index], flags);
>  }

You don't need this,
because memcg_kmem_get_cache() is invoked in both slab_alloc() and
__cache_alloc_node().