Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754430AbZICFyM (ORCPT ); Thu, 3 Sep 2009 01:54:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754328AbZICFyL (ORCPT ); Thu, 3 Sep 2009 01:54:11 -0400 Received: from TYO202.gate.nec.co.jp ([202.32.8.206]:50902 "EHLO tyo202.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751279AbZICFyK (ORCPT ); Thu, 3 Sep 2009 01:54:10 -0400 Date: Thu, 3 Sep 2009 14:17:27 +0900 From: Daisuke Nishimura To: KAMEZAWA Hiroyuki Cc: nishimura@mxp.nes.nec.co.jp, "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: <20090903141727.ccde7e91.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090902182923.c6d98fd6.kamezawa.hiroyu@jp.fujitsu.com> References: <20090902093438.eed47a57.kamezawa.hiroyu@jp.fujitsu.com> <20090902134114.b6f1a04d.kamezawa.hiroyu@jp.fujitsu.com> <20090902182923.c6d98fd6.kamezawa.hiroyu@jp.fujitsu.com> Organization: NEC Soft, Ltd. X-Mailer: Sylpheed 2.6.0 (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: 6380 Lines: 209 On Wed, 2 Sep 2009 18:29:23 +0900, KAMEZAWA Hiroyuki wrote: > I'm sorry that I'll be absent tomorrow. This is dump of current code. > IMHO, this version is enough simple. > > My next target is css's refcnt per page. I think we never need it... > hmm, maybe. > = > 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. 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". > +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. > +} > + > +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. > + struct memcg_stock_pcp *stock; > + > + if (action != CPU_DEAD) > + return NOTIFY_OK; > + stock = per_cpu(memcg_stock, cpu); '&' is needed. > + 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(). > } 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/