From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx116.postini.com [74.125.245.116]) by kanga.kvack.org (Postfix) with SMTP id 701766B006C for ; Mon, 9 Jul 2012 00:20:22 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id B94133EE0C0 for ; Mon, 9 Jul 2012 13:20:20 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 9D4B945DEB6 for ; Mon, 9 Jul 2012 13:20:20 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 8390845DEB3 for ; Mon, 9 Jul 2012 13:20:20 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 759FE1DB8041 for ; Mon, 9 Jul 2012 13:20:20 +0900 (JST) Received: from m1001.s.css.fujitsu.com (m1001.s.css.fujitsu.com [10.240.81.139]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 261FA1DB803B for ; Mon, 9 Jul 2012 13:20:20 +0900 (JST) Message-ID: <4FFA5B7F.8030403@jp.fujitsu.com> Date: Mon, 09 Jul 2012 13:18:07 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 Subject: Re: [PATCH 6/7] memcg: add per cgroup writeback pages accounting References: <1340880885-5427-1-git-send-email-handai.szj@taobao.com> <1340881562-5900-1-git-send-email-handai.szj@taobao.com> <20120708145309.GC18272@localhost> <4FFA51AB.30203@gmail.com> <20120709041437.GA10180@localhost> In-Reply-To: <20120709041437.GA10180@localhost> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Fengguang Wu Cc: Sha Zhengju , linux-mm@kvack.org, cgroups@vger.kernel.org, gthelen@google.com, yinghan@google.com, akpm@linux-foundation.org, mhocko@suse.cz, linux-kernel@vger.kernel.org, Sha Zhengju (2012/07/09 13:14), Fengguang Wu wrote: > On Mon, Jul 09, 2012 at 11:36:11AM +0800, Sha Zhengju wrote: >> On 07/08/2012 10:53 PM, Fengguang Wu wrote: >>>> @@ -2245,7 +2252,10 @@ int test_set_page_writeback(struct page *page) >>>> { >>>> struct address_space *mapping = page_mapping(page); >>>> int ret; >>>> + bool locked; >>>> + unsigned long flags; >>>> >>>> + mem_cgroup_begin_update_page_stat(page,&locked,&flags); >>>> if (mapping) { >>>> struct backing_dev_info *bdi = mapping->backing_dev_info; >>>> unsigned long flags; >>>> @@ -2272,6 +2282,8 @@ int test_set_page_writeback(struct page *page) >>>> } >>>> if (!ret) >>>> account_page_writeback(page); >>>> + >>>> + mem_cgroup_end_update_page_stat(page,&locked,&flags); >>>> return ret; >>>> >>>> } >>> Where is the MEM_CGROUP_STAT_FILE_WRITEBACK increased? >>> >> >> It's in account_page_writeback(). >> >> void account_page_writeback(struct page *page) >> { >> + mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_WRITEBACK); >> inc_zone_page_state(page, NR_WRITEBACK); >> } > > I didn't find that chunk, perhaps it's lost due to rebase.. > >> There isn't a unified interface to dec/inc writeback accounting, so >> I just follow that. >> Maybe we can rework account_page_writeback() to also account >> dec in? > > The current seperate inc/dec paths are fine. It sounds like > over-engineering if going any further. > > I'm a bit worried about some 3rd party kernel module to call > account_page_writeback() without mem_cgroup_begin/end_update_page_stat(). > Will that lead to serious locking issues, or merely inaccurate > accounting? > Ah, Hm. Maybe it's better to add some debug check in mem_cgroup_update_page_stat(). rcu_read_lock_held() or some. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org