Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751565AbZIDEUe (ORCPT ); Fri, 4 Sep 2009 00:20:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751067AbZIDEUe (ORCPT ); Fri, 4 Sep 2009 00:20:34 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:60801 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750991AbZIDEUd (ORCPT ); Fri, 4 Sep 2009 00:20:33 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 4 Sep 2009 13:18:35 +0900 From: KAMEZAWA Hiroyuki To: Daisuke Nishimura Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "balbir@linux.vnet.ibm.com" , "akpm@linux-foundation.org" Subject: Re: [mmotm][experimental][PATCH] coalescing charge Message-Id: <20090904131835.ac2b8cc8.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090903141727.ccde7e91.nishimura@mxp.nes.nec.co.jp> References: <20090902093438.eed47a57.kamezawa.hiroyu@jp.fujitsu.com> <20090902134114.b6f1a04d.kamezawa.hiroyu@jp.fujitsu.com> <20090902182923.c6d98fd6.kamezawa.hiroyu@jp.fujitsu.com> <20090903141727.ccde7e91.nishimura@mxp.nes.nec.co.jp> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (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: 6664 Lines: 225 On Thu, 3 Sep 2009 14:17:27 +0900 Daisuke Nishimura wrote: > > = > > This is a code for batched charging using percpu cache. > > At charge, memcg charges 64pages and remember it in percpu cache. > > Because it's cache, drain/flushed if necessary. > > > > This version uses public percpu area , not per-memcg percpu area. > > 2 benefits of public percpu area. > > 1. Sum of stocked charge in the system is limited to # of cpus > > not to the number of memcg. This shows better synchonization. > > 2. drain code for flush/cpuhotplug is very easy (and quick) > > > > The most important point of this patch is that we never touch res_counter > > in fast path. The res_counter is system-wide shared counter which is modified > > very frequently. We shouldn't touch it as far as we can for avoid false sharing. > > > > Signed-off-by: KAMEZAWA Hiroyuki > It looks basically good. I'll do some tests with all patches applied. > thanks. > I have some comments inlined. > > --- > > mm/memcontrol.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 88 insertions(+), 5 deletions(-) > > > > Index: mmotm-2.6.31-Aug27/mm/memcontrol.c > > =================================================================== > > --- mmotm-2.6.31-Aug27.orig/mm/memcontrol.c > > +++ mmotm-2.6.31-Aug27/mm/memcontrol.c > > @@ -275,6 +275,7 @@ enum charge_type { > > static void mem_cgroup_get(struct mem_cgroup *mem); > > static void mem_cgroup_put(struct mem_cgroup *mem); > > static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem); > > +static void drain_all_stock(void); > > > > static struct mem_cgroup_per_zone * > > mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid) > > @@ -1136,6 +1137,8 @@ static int mem_cgroup_hierarchical_recla > > victim = mem_cgroup_select_victim(root_mem); > > if (victim == root_mem) { > > loop++; > > + if (loop >= 1) > > + drain_all_stock(); > > if (loop >= 2) { > > /* > > * If we have not been able to reclaim > > @@ -1253,6 +1256,79 @@ done: > > unlock_page_cgroup(pc); > > } > > > > +#define CHARGE_SIZE (64 * PAGE_SIZE) > > +struct memcg_stock_pcp { > > + struct mem_cgroup *from; > > + int charge; > > +}; > > +DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock); > > + > It might be better to add "static". > ok. > > +static bool consume_stock(struct mem_cgroup *mem) > > +{ > > + struct memcg_stock_pcp *stock; > > + bool ret = true; > > + > > + stock = &get_cpu_var(memcg_stock); > > + if (mem == stock->from && stock->charge) > > + stock->charge -= PAGE_SIZE; > > + else > > + ret = false; > > + put_cpu_var(memcg_stock); > > + return ret; > > +} > > + > > +static void drain_stock(struct memcg_stock_pcp *stock) > > +{ > > + struct mem_cgroup *old = stock->from; > > + > > + if (stock->charge) { > > + res_counter_uncharge(&old->res, stock->charge); > > + if (do_swap_account) > > + res_counter_uncharge(&old->memsw, stock->charge); > > + } > > + stock->from = NULL; > We must clear stock->charge too. > ok. > > +} > > + > > +static void drain_local_stock(struct work_struct *dummy) > > +{ > > + struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); > > + drain_stock(stock); > > + put_cpu_var(memcg_stock); > > +} > > + > > +static void refill_stock(struct mem_cgroup *mem, int val) > > +{ > > + struct memcg_stock_pcp *stock = &get_cpu_var(memcg_stock); > > + > > + if (stock->from != mem) { > > + drain_stock(stock); > > + stock->from = mem; > > + } > > + stock->charge = val; > > + put_cpu_var(memcg_stock); > > +} > > + > > +static void drain_all_stock(void) > > +{ > > + schedule_on_each_cpu(drain_local_stock); > > +} > > + > > +static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb, > > + unsigned long action, > > + void *hcpu) > > +{ > > +#ifdef CONFIG_HOTPLUG_CPU > > + int cpu = (unsigned long)*hcpu; > '*' isn't needed. > Hmm, ouch. > > + struct memcg_stock_pcp *stock; > > + > > + if (action != CPU_DEAD) > > + return NOTIFY_OK; > > + stock = per_cpu(memcg_stock, cpu); > '&' is needed. > yes.. > > + drain_stock(stock); > > +#endif > > + return NOTIFY_OK; > > +} > > + > > /* > > * Unlike exported interface, "oom" parameter is added. if oom==true, > > * oom-killer can be invoked. > > @@ -1288,23 +1364,25 @@ static int __mem_cgroup_try_charge(struc > > return 0; > > > > VM_BUG_ON(css_is_removed(&mem->css)); > > + if (mem_cgroup_is_root(mem)) > > + goto done; > > + if (consume_stock(mem)) > > + goto charged; > > > > while (1) { > > int ret = 0; > > unsigned long flags = 0; > > > > - if (mem_cgroup_is_root(mem)) > > - goto done; > > - ret = res_counter_charge(&mem->res, PAGE_SIZE, &fail_res); > > + ret = res_counter_charge(&mem->res, CHARGE_SIZE, &fail_res); > > if (likely(!ret)) { > > if (!do_swap_account) > > break; > > - ret = res_counter_charge(&mem->memsw, PAGE_SIZE, > > + ret = res_counter_charge(&mem->memsw, CHARGE_SIZE, > > &fail_res); > > if (likely(!ret)) > > break; > > /* mem+swap counter fails */ > > - res_counter_uncharge(&mem->res, PAGE_SIZE); > > + res_counter_uncharge(&mem->res, CHARGE_SIZE); > > flags |= MEM_CGROUP_RECLAIM_NOSWAP; > > mem_over_limit = mem_cgroup_from_res_counter(fail_res, > > memsw); > > @@ -1342,6 +1420,9 @@ static int __mem_cgroup_try_charge(struc > > goto nomem; > > } > > } > > + refill_stock(mem, CHARGE_SIZE - PAGE_SIZE); > > + > > +charged: > > /* > > * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. > > * if they exceeds softlimit. > > @@ -2448,6 +2529,7 @@ move_account: > > goto out; > > /* This is for making all *used* pages to be on LRU. */ > > lru_add_drain_all(); > > + drain_all_stock(); > > ret = 0; > > for_each_node_state(node, N_HIGH_MEMORY) { > > for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) { > > @@ -3166,6 +3248,7 @@ mem_cgroup_create(struct cgroup_subsys * > > root_mem_cgroup = mem; > > if (mem_cgroup_soft_limit_tree_init()) > > goto free_out; > > + hotcpu_notifier(memcg_stock_cpu_callback, 0); > > > We should include cpu.h to use hotcpu_notifier(). > Ah, I'll check my .config again.. Thanks, -Kame > > } else { > > parent = mem_cgroup_from_cont(cont->parent); > > > > > Thanks, > Daisuke Nishimura. > -- 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/