Re: [PATCH 11/23] slub: consider a memcg parameter in kmem_create_cache

[Suleiman Souhlal <suleiman@google.com>]

On Fri, Apr 20, 2012 at 2:57 PM, Glauber Costa <glommer@parallels.com> wrote:
> Allow a memcg parameter to be passed during cache creation.
> The slub allocator will only merge caches that belong to
> the same memcg.
>
> Default function is created as a wrapper, passing NULL
> to the memcg version. We only merge caches that belong
> to the same memcg.
>
> From the memcontrol.c side, 3 helper functions are created:
>
>  1) memcg_css_id: because slub needs a unique cache name
>    for sysfs. Since this is visible, but not the canonical
>    location for slab data, the cache name is not used, the
>    css_id should suffice.
>
>  2) mem_cgroup_register_cache: is responsible for assigning
>    a unique index to each cache, and other general purpose
>    setup. The index is only assigned for the root caches. All
>    others are assigned index == -1.
>
>  3) mem_cgroup_release_cache: can be called from the root cache
>    destruction, and will release the index for other caches.
>
> This index mechanism was developed by Suleiman Souhlal.
>
> Signed-off-by: Glauber Costa <glommer@parallels.com>
> CC: Christoph Lameter <cl@linux.com>
> CC: Pekka Enberg <penberg@cs.helsinki.fi>
> CC: Michal Hocko <mhocko@suse.cz>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> CC: Johannes Weiner <hannes@cmpxchg.org>
> CC: Suleiman Souhlal <suleiman@google.com>
> ---
>  include/linux/memcontrol.h |   14 ++++++++++++++
>  include/linux/slab.h       |    6 ++++++
>  mm/memcontrol.c            |   29 +++++++++++++++++++++++++++++
>  mm/slub.c                  |   31 +++++++++++++++++++++++++++----
>  4 files changed, 76 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index f94efd2..99e14b9 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -26,6 +26,7 @@ struct mem_cgroup;
>  struct page_cgroup;
>  struct page;
>  struct mm_struct;
> +struct kmem_cache;
>
>  /* Stats that can be updated by kernel. */
>  enum mem_cgroup_page_stat_item {
> @@ -440,7 +441,20 @@ struct sock;
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>  void sock_update_memcg(struct sock *sk);
>  void sock_release_memcg(struct sock *sk);
> +int memcg_css_id(struct mem_cgroup *memcg);
> +void mem_cgroup_register_cache(struct mem_cgroup *memcg,
> +                                     struct kmem_cache *s);
> +void mem_cgroup_release_cache(struct kmem_cache *cachep);
>  #else
> +static inline void mem_cgroup_register_cache(struct mem_cgroup *memcg,
> +                                            struct kmem_cache *s)
> +{
> +}
> +
> +static inline void mem_cgroup_release_cache(struct kmem_cache *cachep)
> +{
> +}
> +
>  static inline void sock_update_memcg(struct sock *sk)
>  {
>  }
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index a5127e1..c7a7e05 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -321,6 +321,12 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
>        __kmalloc(size, flags)
>  #endif /* DEBUG_SLAB */
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +#define MAX_KMEM_CACHE_TYPES 400
> +#else
> +#define MAX_KMEM_CACHE_TYPES 0
> +#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
> +
>  #ifdef CONFIG_NUMA
>  /*
>  * kmalloc_node_track_caller is a special version of kmalloc_node that
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 36f1e6b..0015ed0 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -323,6 +323,11 @@ struct mem_cgroup {
>  #endif
>  };
>
> +int memcg_css_id(struct mem_cgroup *memcg)
> +{
> +       return css_id(&memcg->css);
> +}
> +
>  /* Stuffs for move charges at task migration. */
>  /*
>  * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
> @@ -461,6 +466,30 @@ struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
>  }
>  EXPORT_SYMBOL(tcp_proto_cgroup);
>  #endif /* CONFIG_INET */
> +
> +/* Bitmap used for allocating the cache id numbers. */
> +static DECLARE_BITMAP(cache_types, MAX_KMEM_CACHE_TYPES);
> +
> +void mem_cgroup_register_cache(struct mem_cgroup *memcg,
> +                              struct kmem_cache *cachep)
> +{
> +       int id = -1;
> +
> +       cachep->memcg_params.memcg = memcg;
> +
> +       if (!memcg) {
> +               id = find_first_zero_bit(cache_types, MAX_KMEM_CACHE_TYPES);
> +               BUG_ON(id < 0 || id >= MAX_KMEM_CACHE_TYPES);
> +               __set_bit(id, cache_types);
> +       } else
> +               INIT_LIST_HEAD(&cachep->memcg_params.destroyed_list);
> +       cachep->memcg_params.id = id;
> +}
> +
> +void mem_cgroup_release_cache(struct kmem_cache *cachep)
> +{
> +       __clear_bit(cachep->memcg_params.id, cache_types);
> +}
>  #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
>
>  static void drain_all_stock_async(struct mem_cgroup *memcg);
> diff --git a/mm/slub.c b/mm/slub.c
> index 2652e7c..86e40cc 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -32,6 +32,7 @@
>  #include <linux/prefetch.h>
>
>  #include <trace/events/kmem.h>
> +#include <linux/memcontrol.h>
>
>  /*
>  * Lock order:
> @@ -3880,7 +3881,7 @@ static int slab_unmergeable(struct kmem_cache *s)
>        return 0;
>  }
>
> -static struct kmem_cache *find_mergeable(size_t size,
> +static struct kmem_cache *find_mergeable(struct mem_cgroup *memcg, size_t size,
>                size_t align, unsigned long flags, const char *name,
>                void (*ctor)(void *))
>  {
> @@ -3916,21 +3917,29 @@ static struct kmem_cache *find_mergeable(size_t size,
>                if (s->size - size >= sizeof(void *))
>                        continue;
>
> +               if (memcg && s->memcg_params.memcg != memcg)
> +                       continue;
> +
>                return s;
>        }
>        return NULL;
>  }
>
> -struct kmem_cache *kmem_cache_create(const char *name, size_t size,
> -               size_t align, unsigned long flags, void (*ctor)(void *))
> +struct kmem_cache *
> +kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
> +                       size_t align, unsigned long flags, void (*ctor)(void *))
>  {
>        struct kmem_cache *s;
>
>        if (WARN_ON(!name))
>                return NULL;
>
> +#ifndef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +       WARN_ON(memcg != NULL);
> +#endif
> +
>        down_write(&slub_lock);
> -       s = find_mergeable(size, align, flags, name, ctor);
> +       s = find_mergeable(memcg, size, align, flags, name, ctor);
>        if (s) {
>                s->refcount++;
>                /*
> @@ -3954,12 +3963,15 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
>                                size, align, flags, ctor)) {
>                        list_add(&s->list, &slab_caches);
>                        up_write(&slub_lock);
> +                       mem_cgroup_register_cache(memcg, s);

Do the kmalloc caches get their id registered correctly?

-- Suleiman

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