From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752860Ab2L1Bps (ORCPT ); Thu, 27 Dec 2012 20:45:48 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:60705 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751871Ab2L1Bpr (ORCPT ); Thu, 27 Dec 2012 20:45:47 -0500 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.8.4 Message-ID: <50DCF9AB.3060503@jp.fujitsu.com> Date: Fri, 28 Dec 2012 10:45:15 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Sha Zhengju CC: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, akpm@linux-foundation.org, gthelen@google.com, fengguang.wu@intel.com, glommer@parallels.com, Sha Zhengju Subject: Re: [PATCH V3 7/8] memcg: disable memcg page stat accounting code when not in use References: <1356455919-14445-1-git-send-email-handai.szj@taobao.com> <1356456477-14780-1-git-send-email-handai.szj@taobao.com> In-Reply-To: <1356456477-14780-1-git-send-email-handai.szj@taobao.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2012/12/26 2:27), Sha Zhengju wrote: > From: Sha Zhengju > > It's inspired by a similar optimization from Glauber Costa > (memcg: make it suck faster; https://lkml.org/lkml/2012/9/25/154). > Here we use jump label to patch the memcg page stat accounting code > in or out when not used. when the first non-root memcg comes to > life the code is patching in otherwise it is out. > > Signed-off-by: Sha Zhengju > --- > include/linux/memcontrol.h | 9 +++++++++ > mm/memcontrol.c | 8 ++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 1d22b81..3c4430c 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -56,6 +56,9 @@ struct mem_cgroup_reclaim_cookie { > }; > > #ifdef CONFIG_MEMCG > + > +extern struct static_key memcg_in_use_key; > + > /* > * All "charge" functions with gfp_mask should use GFP_KERNEL or > * (gfp_mask & GFP_RECLAIM_MASK). In current implementatin, memcg doesn't > @@ -158,6 +161,9 @@ extern atomic_t memcg_moving; > static inline void mem_cgroup_begin_update_page_stat(struct page *page, > bool *locked, unsigned long *flags) > { > + if (!static_key_false(&memcg_in_use_key)) > + return; > + > if (mem_cgroup_disabled()) > return; > rcu_read_lock(); > @@ -171,6 +177,9 @@ void __mem_cgroup_end_update_page_stat(struct page *page, > static inline void mem_cgroup_end_update_page_stat(struct page *page, > bool *locked, unsigned long *flags) > { > + if (!static_key_false(&memcg_in_use_key)) > + return; > + > if (mem_cgroup_disabled()) > return; > if (*locked) > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 0cb5187..a2f73d7 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -531,6 +531,8 @@ enum res_type { > #define MEM_CGROUP_RECLAIM_SHRINK_BIT 0x1 > #define MEM_CGROUP_RECLAIM_SHRINK (1 << MEM_CGROUP_RECLAIM_SHRINK_BIT) > > +struct static_key memcg_in_use_key; > + > static void mem_cgroup_get(struct mem_cgroup *memcg); > static void mem_cgroup_put(struct mem_cgroup *memcg); > > @@ -2226,6 +2228,9 @@ void mem_cgroup_update_page_stat(struct page *page, > struct page_cgroup *pc = lookup_page_cgroup(page); > unsigned long uninitialized_var(flags); > > + if (!static_key_false(&memcg_in_use_key)) > + return; > + > if (mem_cgroup_disabled()) > return; > > @@ -6340,6 +6345,8 @@ mem_cgroup_css_alloc(struct cgroup *cont) > parent = mem_cgroup_from_cont(cont->parent); > memcg->use_hierarchy = parent->use_hierarchy; > memcg->oom_kill_disable = parent->oom_kill_disable; > + > + static_key_slow_inc(&memcg_in_use_key); > } > > if (parent && parent->use_hierarchy) { > @@ -6407,6 +6414,7 @@ static void mem_cgroup_css_free(struct cgroup *cont) > kmem_cgroup_destroy(memcg); > > memcg_dangling_add(memcg); > + static_key_slow_dec(&memcg_in_use_key); Hmm. I think this part should be folded into disarm_static_keys(). Thanks, -Kame