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memcg: free memcg_caches slot on css offline

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We need to look up a kmem_cache in ->memcg_params.memcg_caches arrays only
on allocations, so there is no need to have the array entries set until
css free - we can clear them on css offline.  This will allow us to reuse
array entries more efficiently and avoid costly array relocations.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vladimir Davydov 2015-02-12 14:59:32 -08:00 committed by Linus Torvalds
parent f1008365bb
commit 2a4db7eb93
3 changed files with 65 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/slab.h
View File

@ -115,13 +115,12 @@ int slab_is_available(void);
struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
unsigned long,
void (*)(void *));
#ifdef CONFIG_MEMCG_KMEM
void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
void memcg_destroy_kmem_caches(struct mem_cgroup *);
#endif
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
void memcg_create_kmem_cache(struct mem_cgroup *, struct kmem_cache *);
void memcg_deactivate_kmem_caches(struct mem_cgroup *);
void memcg_destroy_kmem_caches(struct mem_cgroup *);
/*
* Please use this macro to create slab caches. Simply specify the
@ -288,6 +287,7 @@ static __always_inline int kmalloc_index(size_t size)
void *__kmalloc(size_t size, gfp_t flags);
void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags);
void kmem_cache_free(struct kmem_cache *, void *);
#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node);

38
mm/memcontrol.c
View File

@ -334,6 +334,7 @@ struct mem_cgroup {
#if defined(CONFIG_MEMCG_KMEM)
/* Index in the kmem_cache->memcg_params.memcg_caches array */
int kmemcg_id;
bool kmem_acct_active;
#endif
int last_scanned_node;
@ -354,7 +355,7 @@ struct mem_cgroup {
#ifdef CONFIG_MEMCG_KMEM
bool memcg_kmem_is_active(struct mem_cgroup *memcg)
{
return memcg->kmemcg_id >= 0;
return memcg->kmem_acct_active;
}
#endif
@ -585,7 +586,7 @@ static void memcg_free_cache_id(int id);
static void disarm_kmem_keys(struct mem_cgroup *memcg)
{
if (memcg_kmem_is_active(memcg)) {
if (memcg->kmemcg_id >= 0) {
static_key_slow_dec(&memcg_kmem_enabled_key);
memcg_free_cache_id(memcg->kmemcg_id);
}
@ -2666,6 +2667,7 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep)
{
struct mem_cgroup *memcg;
struct kmem_cache *memcg_cachep;
int kmemcg_id;
VM_BUG_ON(!is_root_cache(cachep));
@ -2673,10 +2675,11 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep)
return cachep;
memcg = get_mem_cgroup_from_mm(current->mm);
if (!memcg_kmem_is_active(memcg))
kmemcg_id = ACCESS_ONCE(memcg->kmemcg_id);
if (kmemcg_id < 0)
goto out;
memcg_cachep = cache_from_memcg_idx(cachep, memcg_cache_id(memcg));
memcg_cachep = cache_from_memcg_idx(cachep, kmemcg_id);
if (likely(memcg_cachep))
return memcg_cachep;
@ -3318,8 +3321,8 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
int err = 0;
int memcg_id;
if (memcg_kmem_is_active(memcg))
return 0;
BUG_ON(memcg->kmemcg_id >= 0);
BUG_ON(memcg->kmem_acct_active);
/*
* For simplicity, we won't allow this to be disabled. It also can't
@ -3362,6 +3365,7 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
* patched.
*/
memcg->kmemcg_id = memcg_id;
memcg->kmem_acct_active = true;
out:
return err;
}
@ -4041,6 +4045,22 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
return mem_cgroup_sockets_init(memcg, ss);
}
static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
{
if (!memcg->kmem_acct_active)
return;
/*
* Clear the 'active' flag before clearing memcg_caches arrays entries.
* Since we take the slab_mutex in memcg_deactivate_kmem_caches(), it
* guarantees no cache will be created for this cgroup after we are
* done (see memcg_create_kmem_cache()).
*/
memcg->kmem_acct_active = false;
memcg_deactivate_kmem_caches(memcg);
}
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
{
memcg_destroy_kmem_caches(memcg);
@ -4052,6 +4072,10 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
return 0;
}
static void memcg_deactivate_kmem(struct mem_cgroup *memcg)
{
}
static void memcg_destroy_kmem(struct mem_cgroup *memcg)
{
}
@ -4608,6 +4632,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
spin_unlock(&memcg->event_list_lock);
vmpressure_cleanup(&memcg->vmpressure);
memcg_deactivate_kmem(memcg);
}
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)

39
mm/slab_common.c
View File

@ -440,18 +440,8 @@ static int do_kmem_cache_shutdown(struct kmem_cache *s,
*need_rcu_barrier = true;
#ifdef CONFIG_MEMCG_KMEM
if (!is_root_cache(s)) {
int idx;
struct memcg_cache_array *arr;
idx = memcg_cache_id(s->memcg_params.memcg);
arr = rcu_dereference_protected(s->memcg_params.root_cache->
memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
BUG_ON(arr->entries[idx] != s);
arr->entries[idx] = NULL;
if (!is_root_cache(s))
list_del(&s->memcg_params.list);
}
#endif
list_move(&s->list, release);
return 0;
@ -499,6 +489,13 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
mutex_lock(&slab_mutex);
/*
* The memory cgroup could have been deactivated while the cache
* creation work was pending.
*/
if (!memcg_kmem_is_active(memcg))
goto out_unlock;
idx = memcg_cache_id(memcg);
arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
@ -548,6 +545,26 @@ out_unlock:
put_online_cpus();
}
void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
{
int idx;
struct memcg_cache_array *arr;
struct kmem_cache *s;
idx = memcg_cache_id(memcg);
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
if (!is_root_cache(s))
continue;
arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
arr->entries[idx] = NULL;
}
mutex_unlock(&slab_mutex);
}
void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
{
LIST_HEAD(release);