From 2a4db7eb9391a544ff58f4fa11d35246e87c87af Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 12 Feb 2015 14:59:32 -0800 Subject: memcg: free memcg_caches slot on css offline 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 Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 38 ++++++++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 6 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6f3c0fc..abfe013 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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) -- cgit v1.1