From f7ce3190c4a35bf887adb7a1aa1ba899b679872d Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 12 Feb 2015 14:59:20 -0800 Subject: 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 Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Dave Chinner Cc: Dan Carpenter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index afa55bb38cbd..6f3c0fcd7a2d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -332,7 +332,7 @@ struct mem_cgroup { struct cg_proto tcp_mem; #endif #if defined(CONFIG_MEMCG_KMEM) - /* Index in the kmem_cache->memcg_params->memcg_caches array */ + /* Index in the kmem_cache->memcg_params.memcg_caches array */ int kmemcg_id; #endif @@ -531,7 +531,7 @@ static void disarm_sock_keys(struct mem_cgroup *memcg) #ifdef CONFIG_MEMCG_KMEM /* - * This will be the memcg's index in each cache's ->memcg_params->memcg_caches. + * This will be the memcg's index in each cache's ->memcg_params.memcg_caches. * The main reason for not using cgroup id for this: * this works better in sparse environments, where we have a lot of memcgs, * but only a few kmem-limited. Or also, if we have, for instance, 200 @@ -2667,8 +2667,7 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep) struct mem_cgroup *memcg; struct kmem_cache *memcg_cachep; - VM_BUG_ON(!cachep->memcg_params); - VM_BUG_ON(!cachep->memcg_params->is_root_cache); + VM_BUG_ON(!is_root_cache(cachep)); if (current->memcg_kmem_skip_account) return cachep; @@ -2702,7 +2701,7 @@ out: void __memcg_kmem_put_cache(struct kmem_cache *cachep) { if (!is_root_cache(cachep)) - css_put(&cachep->memcg_params->memcg->css); + css_put(&cachep->memcg_params.memcg->css); } /* @@ -2778,7 +2777,7 @@ struct mem_cgroup *__mem_cgroup_from_kmem(void *ptr) if (PageSlab(page)) { cachep = page->slab_cache; if (!is_root_cache(cachep)) - memcg = cachep->memcg_params->memcg; + memcg = cachep->memcg_params.memcg; } else /* page allocated by alloc_kmem_pages */ memcg = page->mem_cgroup; -- cgit v1.2.3-58-ga151