Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753899AbZICAe0 (ORCPT ); Wed, 2 Sep 2009 20:34:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752792AbZICAeZ (ORCPT ); Wed, 2 Sep 2009 20:34:25 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:50517 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356AbZICAeY (ORCPT ); Wed, 2 Sep 2009 20:34:24 -0400 Message-ID: In-Reply-To: <661de9470909021315m3af0de32h29f1ac8fd574249d@mail.gmail.com> References: <20090902093438.eed47a57.kamezawa.hiroyu@jp.fujitsu.com> <20090902093551.c8b171fb.kamezawa.hiroyu@jp.fujitsu.com> <20090902145621.83c8a79c.kamezawa.hiroyu@jp.fujitsu.com> <661de9470909021315m3af0de32h29f1ac8fd574249d@mail.gmail.com> Date: Thu, 3 Sep 2009 09:34:23 +0900 (JST) Subject: Re: [mmotm][PATCH 2/2 v2] memcg: reduce calls for soft limit excess From: "KAMEZAWA Hiroyuki" To: "Balbir Singh" Cc: "KAMEZAWA Hiroyuki" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "akpm@linux-foundation.org" User-Agent: SquirrelMail/1.4.16 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-2022-jp Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) Importance: Normal Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9164 Lines: 192 Balbir Singh さんは書きました： > 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. > will do when I sent out v3. (and I'll have to do, anyway.) Bye, -Kame > > >> 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 > -- 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/