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authorVladimir Davydov <vdavydov@parallels.com>2015-02-13 01:59:20 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-13 05:54:09 +0300
commitf7ce3190c4a35bf887adb7a1aa1ba899b679872d (patch)
tree8a40d93f1e796e1007d59e67541ce3044430b927 /include/linux/slab_def.h
parent49e7e7ff8d551b5b1e2f8da8497b9058cfa25672 (diff)
downloadlinux-f7ce3190c4a35bf887adb7a1aa1ba899b679872d.tar.xz
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 'include/linux/slab_def.h')
-rw-r--r--include/linux/slab_def.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index b869d1662ba3..33d049066c3d 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -70,7 +70,7 @@ struct kmem_cache {
int obj_offset;
#endif /* CONFIG_DEBUG_SLAB */
#ifdef CONFIG_MEMCG_KMEM
- struct memcg_cache_params *memcg_params;
+ struct memcg_cache_params memcg_params;
#endif
struct kmem_cache_node *node[MAX_NUMNODES];