Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752369Ab0BCHXJ (ORCPT ); Wed, 3 Feb 2010 02:23:09 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:55030 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920Ab0BCHXE (ORCPT ); Wed, 3 Feb 2010 02:23:04 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 3 Feb 2010 16:19:36 +0900 From: KAMEZAWA Hiroyuki To: balbir@linux.vnet.ibm.com Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" Subject: Re: [PATCH mmotm] memcg: use generic percpu instead of private implementation Message-Id: <20100203161936.e45955b5.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100203065305.GD19641@balbir.in.ibm.com> References: <20100203121624.bab7be2c.kamezawa.hiroyu@jp.fujitsu.com> <20100203065305.GD19641@balbir.in.ibm.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.7.1 (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: 6317 Lines: 193 On Wed, 3 Feb 2010 12:23:05 +0530 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2010-02-03 12:16:24]: > > > This is a repost. I'll post my test program in reply to this. > > Updated against mmotm-2010-Feb-01. > > > > Thanks, > > -Kame > > == > > From: KAMEZAWA Hiroyuki > > > > When per-cpu counter for memcg was implemneted, dynamic percpu allocator > > was not very good. But now, we have good one and useful macros. > > This patch replaces memcg's private percpu counter implementation with > > generic dynamic percpu allocator. > > > > The benefits are > > - We can remove private implementation. > > - The counters will be NUMA-aware. (Current one is not...) > > - This patch makes sizeof struct mem_cgroup smaller. Then, > > struct mem_cgroup may be fit in page size on small config. > > - About basic performance aspects, see below. > > > > [Before] > > # size mm/memcontrol.o > > text data bss dec hex filename > > 24373 2528 4132 31033 7939 mm/memcontrol.o > > > > [page-fault-throuput test on 8cpu/SMP in root cgroup] > > # /root/bin/perf stat -a -e page-faults,cache-misses --repeat 5 ./multi-fault-fork 8 > > > > Performance counter stats for './multi-fault-fork 8' (5 runs): > > > > 45878618 page-faults ( +- 0.110% ) > > 602635826 cache-misses ( +- 0.105% ) > > > > 61.005373262 seconds time elapsed ( +- 0.004% ) > > > > Then cache-miss/page fault = 13.14 > > > > [After] > > #size mm/memcontrol.o > > text data bss dec hex filename > > 23913 2528 4132 30573 776d mm/memcontrol.o > > # /root/bin/perf stat -a -e page-faults,cache-misses --repeat 5 ./multi-fault-fork 8 > > > > Performance counter stats for './multi-fault-fork 8' (5 runs): > > > > 48179400 page-faults ( +- 0.271% ) > > 588628407 cache-misses ( +- 0.136% ) > > > > 61.004615021 seconds time elapsed ( +- 0.004% ) > > > > Then cache-miss/page fault = 12.22 > > > > Text size is reduced. > > This performance improvement is not big and will be invisible in real world > > applications. But this result shows this patch has some good effect even > > on (small) SMP. > > > > Changelog: 2010/02/02 > > - adjusted to mmotm-Feb01. > > - added performance result to the patch description. > > > > Signed-off-by: KAMEZAWA Hiroyuki > > --- > > mm/memcontrol.c | 184 +++++++++++++++++++------------------------------------- > > 1 file changed, 63 insertions(+), 121 deletions(-) > > > > Index: mmotm-2.6.33-Feb01/mm/memcontrol.c > > =================================================================== > > --- mmotm-2.6.33-Feb01.orig/mm/memcontrol.c > > +++ mmotm-2.6.33-Feb01/mm/memcontrol.c > > @@ -89,54 +89,8 @@ enum mem_cgroup_stat_index { > > > > struct mem_cgroup_stat_cpu { > > s64 count[MEM_CGROUP_STAT_NSTATS]; > > -} ____cacheline_aligned_in_smp; > > - > > -struct mem_cgroup_stat { > > - struct mem_cgroup_stat_cpu cpustat[0]; > > }; > > > > -static inline void > > -__mem_cgroup_stat_set_safe(struct mem_cgroup_stat_cpu *stat, > > - enum mem_cgroup_stat_index idx, s64 val) > > -{ > > - stat->count[idx] = val; > > -} > > - > > -static inline s64 > > -__mem_cgroup_stat_read_local(struct mem_cgroup_stat_cpu *stat, > > - enum mem_cgroup_stat_index idx) > > -{ > > - return stat->count[idx]; > > -} > > - > > -/* > > - * For accounting under irq disable, no need for increment preempt count. > > - */ > > -static inline void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat_cpu *stat, > > - enum mem_cgroup_stat_index idx, int val) > > -{ > > - stat->count[idx] += val; > > -} > > - > > -static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat, > > - enum mem_cgroup_stat_index idx) > > -{ > > - int cpu; > > - s64 ret = 0; > > - for_each_possible_cpu(cpu) > > - ret += stat->cpustat[cpu].count[idx]; > > - return ret; > > -} > > - > > -static s64 mem_cgroup_local_usage(struct mem_cgroup_stat *stat) > > -{ > > - s64 ret; > > - > > - ret = mem_cgroup_read_stat(stat, MEM_CGROUP_STAT_CACHE); > > - ret += mem_cgroup_read_stat(stat, MEM_CGROUP_STAT_RSS); > > - return ret; > > -} > > - > > /* > > * per-zone information in memory controller. > > */ > > @@ -270,9 +224,9 @@ struct mem_cgroup { > > unsigned long move_charge_at_immigrate; > > > > /* > > - * statistics. This must be placed at the end of memcg. > > + * percpu counter. > > */ > > - struct mem_cgroup_stat stat; > > + struct mem_cgroup_stat_cpu *stat; > > }; > > > > /* Stuffs for move charges at task migration. */ > > @@ -441,19 +395,14 @@ mem_cgroup_remove_exceeded(struct mem_cg > > static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem) > > { > > bool ret = false; > > - int cpu; > > s64 val; > > - struct mem_cgroup_stat_cpu *cpustat; > > > > - cpu = get_cpu(); > > - cpustat = &mem->stat.cpustat[cpu]; > > - val = __mem_cgroup_stat_read_local(cpustat, MEM_CGROUP_STAT_SOFTLIMIT); > > + val = this_cpu_read(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT]); > > if (unlikely(val < 0)) { > > - __mem_cgroup_stat_set_safe(cpustat, MEM_CGROUP_STAT_SOFTLIMIT, > > + this_cpu_write(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT], > > SOFTLIMIT_EVENTS_THRESH); > > ret = true; > > } > > - put_cpu(); > > return ret; > > } > > > > @@ -549,17 +498,31 @@ mem_cgroup_largest_soft_limit_node(struc > > return mz; > > } > > > > +static s64 mem_cgroup_read_stat(struct mem_cgroup *mem, > > + enum mem_cgroup_stat_index idx) > > +{ > > + int cpu; > > + s64 val = 0; > > + > > + for_each_possible_cpu(cpu) > > Is for_each_possible_cpu() what we need? Is this to avoid CPU hotplug > events? > > Looks good overall, except the question above. Yes. It's against cpu hotplug. Further improvement is add a cpu hotplug handler (and merge date to other cpus). But I think it should be another patch. Thanks, -Kame -- 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/