Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751508Ab0HTKEQ (ORCPT ); Fri, 20 Aug 2010 06:04:16 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:33574 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970Ab0HTKEP (ORCPT ); Fri, 20 Aug 2010 06:04:15 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 20 Aug 2010 18:59:17 +0900 From: KAMEZAWA Hiroyuki To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" , gthelen@google.com, m-ikeda@ds.jp.nec.com, "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , kamezawa.hiroyuki@gmail.com Subject: [PATCH 2/5] memcg: use array and ID for quick look up Message-Id: <20100820185917.87876cb0.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100820185552.426ff12e.kamezawa.hiroyu@jp.fujitsu.com> References: <20100820185552.426ff12e.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7666 Lines: 258 From: KAMEZAWA Hiroyuki 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: 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 --- init/Kconfig | 10 ++++++ mm/memcontrol.c | 83 ++++++++++++++++++++++++++++++++++++++++++-------------- 2 files changed, 73 insertions(+), 20 deletions(-) Index: mmotm-0811/mm/memcontrol.c =================================================================== --- mmotm-0811.orig/mm/memcontrol.c +++ mmotm-0811/mm/memcontrol.c @@ -195,6 +195,7 @@ static void mem_cgroup_oom_notify(struct */ struct mem_cgroup { struct cgroup_subsys_state css; + int valid; /* for checking validness under RCU access.*/ /* * the counter to account for memory usage */ @@ -294,6 +295,29 @@ 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 *ret; + /* see mem_cgroup_free() */ + ret = rcu_dereference_check(mem_cgroups[id], rch_read_lock_held()); + if (likely(ret && ret->valid)) + return ret; + return NULL; +} + +static void register_memcg_id(struct mem_cgroup *mem) +{ + int id = css_id(&mem->css); + rcu_assign_pointer(mem_cgroups[id], mem); + VM_BUG_ON(!mem->valid); +} + /* * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft * limit reclaim to prevent infinite loops, if they ever occur. @@ -1847,18 +1871,7 @@ 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 +1892,7 @@ 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 +2244,7 @@ __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 +2253,10 @@ __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 +2509,7 @@ 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 +2518,10 @@ 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 +4025,9 @@ 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); @@ -4020,6 +4038,7 @@ static struct mem_cgroup *mem_cgroup_all return NULL; memset(mem, 0, size); + mem->valid = 1; mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu); if (!mem->stat) { if (size < PAGE_SIZE) @@ -4049,6 +4068,7 @@ 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 +4079,19 @@ static void __mem_cgroup_free(struct mem vfree(mem); } +static void mem_cgroup_free(struct mem_cgroup *mem) +{ + /* No more lookup */ + mem->valid = 0; + rcu_assign_pointer(mem_cgroups[css_id(&mem->css)], NULL); + /* + * Because we call vfree() etc...use synchronize_rcu() rather than + * call_rcu(); + */ + synchronize_rcu(); + __mem_cgroup_free(mem); +} + static void mem_cgroup_get(struct mem_cgroup *mem) { atomic_inc(&mem->refcnt); @@ -4068,7 +4101,7 @@ 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); } @@ -4184,13 +4217,22 @@ mem_cgroup_create(struct cgroup_subsys * atomic_set(&mem->refcnt, 1); mem->move_charge_at_immigrate = 0; mutex_init(&mem->thresholds_lock); + atomic_inc(&mem_cgroup_num); return &mem->css; free_out: - __mem_cgroup_free(mem); + mem_cgroup_free(mem); root_mem_cgroup = NULL; return ERR_PTR(error); } +static void +mem_cgroup_id_attached(struct cgroup_subsys *ss, struct cgroup *cont) +{ + struct mem_cgroup *mem = mem_cgroup_from_cont(cont); + + register_memcg_id(mem); +} + static int mem_cgroup_pre_destroy(struct cgroup_subsys *ss, struct cgroup *cont) { @@ -4714,6 +4756,7 @@ struct cgroup_subsys mem_cgroup_subsys = .can_attach = mem_cgroup_can_attach, .cancel_attach = mem_cgroup_cancel_attach, .attach = mem_cgroup_move_task, + .id_attached = mem_cgroup_id_attached, .early_init = 0, .use_id = 1, }; Index: mmotm-0811/init/Kconfig =================================================================== --- mmotm-0811.orig/init/Kconfig +++ mmotm-0811/init/Kconfig @@ -594,6 +594,16 @@ 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/