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authorVladimir Davydov <vdavydov@parallels.com>2015-02-12 14:59:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:09 -0800
commitf7ce3190c4a35bf887adb7a1aa1ba899b679872d (patch)
tree8a40d93f1e796e1007d59e67541ce3044430b927 /mm/slab.h
parent49e7e7ff8d551b5b1e2f8da8497b9058cfa25672 (diff)
downloadlinux-f7ce3190c4a35bf887adb7a1aa1ba899b679872d.tar.bz2
slab: embed memcg_cache_params to kmem_cache
Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. 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> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.h')
-rw-r--r--mm/slab.h48
1 files changed, 23 insertions, 25 deletions
diff --git a/mm/slab.h b/mm/slab.h
index 90430d6f665e..53a623f85931 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -86,8 +86,6 @@ extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
extern void create_boot_cache(struct kmem_cache *, const char *name,
size_t size, unsigned long flags);
-struct mem_cgroup;
-
int slab_unmergeable(struct kmem_cache *s);
struct kmem_cache *find_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *));
@@ -167,14 +165,13 @@ ssize_t slabinfo_write(struct file *file, const char __user *buffer,
#ifdef CONFIG_MEMCG_KMEM
static inline bool is_root_cache(struct kmem_cache *s)
{
- return !s->memcg_params || s->memcg_params->is_root_cache;
+ return s->memcg_params.is_root_cache;
}
static inline bool slab_equal_or_root(struct kmem_cache *s,
- struct kmem_cache *p)
+ struct kmem_cache *p)
{
- return (p == s) ||
- (s->memcg_params && (p == s->memcg_params->root_cache));
+ return p == s || p == s->memcg_params.root_cache;
}
/*
@@ -185,37 +182,30 @@ static inline bool slab_equal_or_root(struct kmem_cache *s,
static inline const char *cache_name(struct kmem_cache *s)
{
if (!is_root_cache(s))
- return s->memcg_params->root_cache->name;
+ s = s->memcg_params.root_cache;
return s->name;
}
/*
* Note, we protect with RCU only the memcg_caches array, not per-memcg caches.
- * That said the caller must assure the memcg's cache won't go away. Since once
- * created a memcg's cache is destroyed only along with the root cache, it is
- * true if we are going to allocate from the cache or hold a reference to the
- * root cache by other means. Otherwise, we should hold either the slab_mutex
- * or the memcg's slab_caches_mutex while calling this function and accessing
- * the returned value.
+ * That said the caller must assure the memcg's cache won't go away by either
+ * taking a css reference to the owner cgroup, or holding the slab_mutex.
*/
static inline struct kmem_cache *
cache_from_memcg_idx(struct kmem_cache *s, int idx)
{
struct kmem_cache *cachep;
- struct memcg_cache_params *params;
-
- if (!s->memcg_params)
- return NULL;
+ struct memcg_cache_array *arr;
rcu_read_lock();
- params = rcu_dereference(s->memcg_params);
+ arr = rcu_dereference(s->memcg_params.memcg_caches);
/*
* Make sure we will access the up-to-date value. The code updating
* memcg_caches issues a write barrier to match this (see
- * memcg_register_cache()).
+ * memcg_create_kmem_cache()).
*/
- cachep = lockless_dereference(params->memcg_caches[idx]);
+ cachep = lockless_dereference(arr->entries[idx]);
rcu_read_unlock();
return cachep;
@@ -225,7 +215,7 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
{
if (is_root_cache(s))
return s;
- return s->memcg_params->root_cache;
+ return s->memcg_params.root_cache;
}
static __always_inline int memcg_charge_slab(struct kmem_cache *s,
@@ -235,7 +225,7 @@ static __always_inline int memcg_charge_slab(struct kmem_cache *s,
return 0;
if (is_root_cache(s))
return 0;
- return memcg_charge_kmem(s->memcg_params->memcg, gfp, 1 << order);
+ return memcg_charge_kmem(s->memcg_params.memcg, gfp, 1 << order);
}
static __always_inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
@@ -244,9 +234,13 @@ static __always_inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
return;
if (is_root_cache(s))
return;
- memcg_uncharge_kmem(s->memcg_params->memcg, 1 << order);
+ memcg_uncharge_kmem(s->memcg_params.memcg, 1 << order);
}
-#else
+
+extern void slab_init_memcg_params(struct kmem_cache *);
+
+#else /* !CONFIG_MEMCG_KMEM */
+
static inline bool is_root_cache(struct kmem_cache *s)
{
return true;
@@ -282,7 +276,11 @@ static inline int memcg_charge_slab(struct kmem_cache *s, gfp_t gfp, int order)
static inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
{
}
-#endif
+
+static inline void slab_init_memcg_params(struct kmem_cache *s)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
{