From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Now, memory cgroup has an ID per cgroup and make use of it at - hierarchy walk, - swap recording. This patch is for making more use of it. The final purpose is to replace page_cgroup->mem_cgroup's pointer to an unsigned short. This patch caches a pointer of memcg in an array. By this, we don't have to call css_lookup() which requires radix-hash walk. This saves some amount of memory footprint at lookup memcg via id. Changelog: 20100901 - added unregster_memcg_id() and did some clean up. - removed ->valid. - fixed mem_cgroup_num counter handling. Changelog: 20100825 - applied comments. Changelog: 20100811 - adjusted onto mmotm-2010-08-11 - fixed RCU related parts. - use attach_id() callback. Changelog: 20100804 - fixed description in init/Kconfig Changelog: 20100730 - fixed rcu_read_unlock() placement. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> --- init/Kconfig | 10 +++++++ mm/memcontrol.c | 71 ++++++++++++++++++++++++++++++++++++++++---------------- 2 files changed, 61 insertions(+), 20 deletions(-) Index: mmotm-0827/mm/memcontrol.c =================================================================== --- mmotm-0827.orig/mm/memcontrol.c +++ mmotm-0827/mm/memcontrol.c @@ -294,6 +294,33 @@ static bool move_file(void) &mc.to->move_charge_at_immigrate); } +/* 0 is unused */ +static atomic_t mem_cgroup_num; +#define NR_MEMCG_GROUPS (CONFIG_MEM_CGROUP_MAX_GROUPS + 1) +static struct mem_cgroup *mem_cgroups[NR_MEMCG_GROUPS] __read_mostly; + +/* Must be called under rcu_read_lock */ +static struct mem_cgroup *id_to_memcg(unsigned short id) +{ + struct mem_cgroup *mem; + mem = rcu_dereference_check(mem_cgroups[id], rcu_read_lock_held()); + return mem; +} + +static void register_memcg_id(struct mem_cgroup *mem) +{ + int id = css_id(&mem->css); + rcu_assign_pointer(mem_cgroups[id], mem); +} + +static void unregister_memcg_id(struct mem_cgroup *mem) +{ + int id = css_id(&mem->css); + rcu_assign_pointer(mem_cgroups[id], NULL); + /* Wait until all references goes. */ + synchronize_rcu(); +} + /* * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft * limit reclaim to prevent infinite loops, if they ever occur. @@ -1847,18 +1874,7 @@ static void mem_cgroup_cancel_charge(str * it's concern. (dropping refcnt from swap can be called against removed * memcg.) */ -static struct mem_cgroup *mem_cgroup_lookup(unsigned short id) -{ - struct cgroup_subsys_state *css; - /* ID 0 is unused ID */ - if (!id) - return NULL; - css = css_lookup(&mem_cgroup_subsys, id); - if (!css) - return NULL; - return container_of(css, struct mem_cgroup, css); -} struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) { @@ -1879,7 +1895,7 @@ struct mem_cgroup *try_get_mem_cgroup_fr ent.val = page_private(page); id = lookup_swap_cgroup(ent); rcu_read_lock(); - mem = mem_cgroup_lookup(id); + mem = id_to_memcg(id); if (mem && !css_tryget(&mem->css)) mem = NULL; rcu_read_unlock(); @@ -2231,7 +2247,7 @@ __mem_cgroup_commit_charge_swapin(struct id = swap_cgroup_record(ent, 0); rcu_read_lock(); - memcg = mem_cgroup_lookup(id); + memcg = id_to_memcg(id); if (memcg) { /* * This recorded memcg can be obsolete one. So, avoid @@ -2240,9 +2256,10 @@ __mem_cgroup_commit_charge_swapin(struct if (!mem_cgroup_is_root(memcg)) res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_swap_statistics(memcg, false); + rcu_read_unlock(); mem_cgroup_put(memcg); - } - rcu_read_unlock(); + } else + rcu_read_unlock(); } /* * At swapin, we may charge account against cgroup which has no tasks. @@ -2495,7 +2512,7 @@ void mem_cgroup_uncharge_swap(swp_entry_ id = swap_cgroup_record(ent, 0); rcu_read_lock(); - memcg = mem_cgroup_lookup(id); + memcg = id_to_memcg(id); if (memcg) { /* * We uncharge this because swap is freed. @@ -2504,9 +2521,10 @@ void mem_cgroup_uncharge_swap(swp_entry_ if (!mem_cgroup_is_root(memcg)) res_counter_uncharge(&memcg->memsw, PAGE_SIZE); mem_cgroup_swap_statistics(memcg, false); + rcu_read_unlock(); mem_cgroup_put(memcg); - } - rcu_read_unlock(); + } else + rcu_read_unlock(); } /** @@ -4010,6 +4028,9 @@ static struct mem_cgroup *mem_cgroup_all struct mem_cgroup *mem; int size = sizeof(struct mem_cgroup); + if (atomic_read(&mem_cgroup_num) == NR_MEMCG_GROUPS) + return NULL; + /* Can be very big if MAX_NUMNODES is very big */ if (size < PAGE_SIZE) mem = kmalloc(size, GFP_KERNEL); @@ -4028,6 +4049,8 @@ static struct mem_cgroup *mem_cgroup_all vfree(mem); mem = NULL; } + if (mem) + atomic_inc(&mem_cgroup_num); return mem; } @@ -4049,6 +4072,7 @@ static void __mem_cgroup_free(struct mem mem_cgroup_remove_from_trees(mem); free_css_id(&mem_cgroup_subsys, &mem->css); + atomic_dec(&mem_cgroup_num); for_each_node_state(node, N_POSSIBLE) free_mem_cgroup_per_zone_info(mem, node); @@ -4059,6 +4083,12 @@ static void __mem_cgroup_free(struct mem vfree(mem); } +static void mem_cgroup_free(struct mem_cgroup *mem) +{ + unregister_memcg_id(mem); + __mem_cgroup_free(mem); +} + static void mem_cgroup_get(struct mem_cgroup *mem) { atomic_inc(&mem->refcnt); @@ -4068,7 +4098,7 @@ static void __mem_cgroup_put(struct mem_ { if (atomic_sub_and_test(count, &mem->refcnt)) { struct mem_cgroup *parent = parent_mem_cgroup(mem); - __mem_cgroup_free(mem); + mem_cgroup_free(mem); if (parent) mem_cgroup_put(parent); } @@ -4189,9 +4219,10 @@ mem_cgroup_create(struct cgroup_subsys * atomic_set(&mem->refcnt, 1); mem->move_charge_at_immigrate = 0; mutex_init(&mem->thresholds_lock); + register_memcg_id(mem); return &mem->css; free_out: - __mem_cgroup_free(mem); + mem_cgroup_free(mem); root_mem_cgroup = NULL; return ERR_PTR(error); } Index: mmotm-0827/init/Kconfig =================================================================== --- mmotm-0827.orig/init/Kconfig +++ mmotm-0827/init/Kconfig @@ -612,6 +612,16 @@ config CGROUP_MEM_RES_CTLR_SWAP Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page size is 4096bytes, 512k per 1Gbytes of swap. +config MEM_CGROUP_MAX_GROUPS + int "Maximum number of memory cgroups on a system" + range 1 65535 + default 8192 if 64BIT + default 2048 if 32BIT + help + Memory cgroup has limitation of the number of groups created. + Please select your favorite value. The more you allow, the more + memory(a pointer per group) will be consumed. + menuconfig CGROUP_SCHED bool "Group CPU scheduler" depends on EXPERIMENTAL && CGROUPS -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>