From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752565AbZIBUPH (ORCPT ); Wed, 2 Sep 2009 16:15:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751528AbZIBUPG (ORCPT ); Wed, 2 Sep 2009 16:15:06 -0400 Received: from mail-px0-f204.google.com ([209.85.216.204]:43148 "EHLO mail-px0-f204.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750943AbZIBUPE convert rfc822-to-8bit (ORCPT ); Wed, 2 Sep 2009 16:15:04 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=r4HrP2VTNNnrmHzrnctC1YwLDuYmhMzAk8GAQ0cX243snm4iCixMJU23zrKqbDsYjO ZBa+6N9//IXJXRVwRGQhabpFIV/qwLvD22gWBObQLVr94zj31gi7ut1cbvhIRy3uqToR QECgtr7RKErz7a0PGtPCemsk8ULhGygB/9wbE= MIME-Version: 1.0 In-Reply-To: <20090902145621.83c8a79c.kamezawa.hiroyu@jp.fujitsu.com> References: <20090902093438.eed47a57.kamezawa.hiroyu@jp.fujitsu.com> <20090902093551.c8b171fb.kamezawa.hiroyu@jp.fujitsu.com> <20090902145621.83c8a79c.kamezawa.hiroyu@jp.fujitsu.com> Date: Thu, 3 Sep 2009 01:45:06 +0530 X-Google-Sender-Auth: 57f8f0181a6e0c82 Message-ID: <661de9470909021315m3af0de32h29f1ac8fd574249d@mail.gmail.com> Subject: Re: [mmotm][PATCH 2/2 v2] memcg: reduce calls for soft limit excess From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "akpm@linux-foundation.org" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 2, 2009 at 11:26 AM, KAMEZAWA Hiroyuki wrote: > In charge/uncharge/reclaim path, usage_in_excess is calculated repeatedly and > it takes res_counter's spin_lock every time. > I think the changelog needs to mention some refactoring you've done below as well, like change new_charge_in_excess to excess. > This patch removes unnecessary calls for res_count_soft_limit_excess. > > Changelog: >  - fixed description. >  - fixed unsigned long to be unsigned long long (Thanks, Nishimura) > > Reviewed-by: Daisuke Nishimura > Signed-off-by: KAMEZAWA Hiroyuki > --- >  mm/memcontrol.c |   31 +++++++++++++++---------------- >  1 file changed, 15 insertions(+), 16 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 > @@ -313,7 +313,8 @@ soft_limit_tree_from_page(struct page *p >  static void >  __mem_cgroup_insert_exceeded(struct mem_cgroup *mem, >                                struct mem_cgroup_per_zone *mz, > -                               struct mem_cgroup_tree_per_zone *mctz) > +                               struct mem_cgroup_tree_per_zone *mctz, > +                               unsigned long long new_usage_in_excess) >  { >        struct rb_node **p = &mctz->rb_root.rb_node; >        struct rb_node *parent = NULL; > @@ -322,7 +323,9 @@ __mem_cgroup_insert_exceeded(struct mem_ >        if (mz->on_tree) >                return; > > -       mz->usage_in_excess = res_counter_soft_limit_excess(&mem->res); > +       mz->usage_in_excess = new_usage_in_excess; > +       if (!mz->usage_in_excess) > +               return; >        while (*p) { >                parent = *p; >                mz_node = rb_entry(parent, struct mem_cgroup_per_zone, > @@ -382,7 +385,7 @@ static bool mem_cgroup_soft_limit_check( > >  static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page) >  { > -       unsigned long long new_usage_in_excess; > +       unsigned long long excess; >        struct mem_cgroup_per_zone *mz; >        struct mem_cgroup_tree_per_zone *mctz; >        int nid = page_to_nid(page); > @@ -395,25 +398,21 @@ static void mem_cgroup_update_tree(struc >         */ >        for (; mem; mem = parent_mem_cgroup(mem)) { >                mz = mem_cgroup_zoneinfo(mem, nid, zid); > -               new_usage_in_excess = > -                       res_counter_soft_limit_excess(&mem->res); > +               excess = res_counter_soft_limit_excess(&mem->res); >                /* >                 * We have to update the tree if mz is on RB-tree or >                 * mem is over its softlimit. >                 */ > -               if (new_usage_in_excess || mz->on_tree) { > +               if (excess || mz->on_tree) { >                        spin_lock(&mctz->lock); >                        /* if on-tree, remove it */ >                        if (mz->on_tree) >                                __mem_cgroup_remove_exceeded(mem, mz, mctz); >                        /* > -                        * if over soft limit, insert again. mz->usage_in_excess > -                        * will be updated properly. > +                        * Insert again. mz->usage_in_excess will be updated. > +                        * If excess is 0, no tree ops. >                         */ > -                       if (new_usage_in_excess) > -                               __mem_cgroup_insert_exceeded(mem, mz, mctz); > -                       else > -                               mz->usage_in_excess = 0; > +                       __mem_cgroup_insert_exceeded(mem, mz, mctz, excess); >                        spin_unlock(&mctz->lock); >                } >        } > @@ -2216,6 +2215,7 @@ unsigned long mem_cgroup_soft_limit_recl >        unsigned long reclaimed; >        int loop = 0; >        struct mem_cgroup_tree_per_zone *mctz; > +       unsigned long long excess; > >        if (order > 0) >                return 0; > @@ -2260,9 +2260,8 @@ unsigned long mem_cgroup_soft_limit_recl >                                __mem_cgroup_largest_soft_limit_node(mctz); >                        } while (next_mz == mz); >                } > -               mz->usage_in_excess = > -                       res_counter_soft_limit_excess(&mz->mem->res); >                __mem_cgroup_remove_exceeded(mz->mem, mz, mctz); > +               excess = res_counter_soft_limit_excess(&mz->mem->res); >                /* >                 * One school of thought says that we should not add >                 * back the node to the tree if reclaim returns 0. > @@ -2271,8 +2270,8 @@ unsigned long mem_cgroup_soft_limit_recl >                 * memory to reclaim from. Consider this as a longer >                 * term TODO. >                 */ > -               if (mz->usage_in_excess) > -                       __mem_cgroup_insert_exceeded(mz->mem, mz, mctz); > +               /* If excess == 0, no tree ops */ > +               __mem_cgroup_insert_exceeded(mz->mem, mz, mctz, excess); >                spin_unlock(&mctz->lock); >                css_put(&mz->mem->css); >                loop++; OK.. so everytime we call __mem_cgroup_insert_exceeded we save one res_counter operation. Looks good Acked-by: Balbir Singh Balbir Singh