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SubjectRe: [PATCH 11/23] slub: consider a memcg parameter in kmem_create_cache
(2012/04/21 6:57), Glauber Costa 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 */
> +


why 400 ?


> #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);


No lock here ? you need find_first_zero_bit_and_set_atomic() or some.
Rather than that, I think you can use lib/idr.c::ida_simple_get().

> + } 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


I'm sorry what's is this warning for ?


> @@ -5265,6 +5283,11 @@ static char *create_unique_id(struct kmem_cache *s)
> if (p != name + 1)
> *p++ = '-';
> p += sprintf(p, "%07d", s->size);
> +
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + if (s->memcg_params.memcg)
> + p += sprintf(p, "-%08d", memcg_css_id(s->memcg_params.memcg));
> +#endif
> BUG_ON(p > name + ID_STR_LENGTH - 1);
> return name;
> }


So, you use 'id' in user interface. Should we provide 'id' as memory.id file ?

Thanks,
-Kame



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