From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx110.postini.com [74.125.245.110]) by kanga.kvack.org (Postfix) with SMTP id 79F548D0001 for ; Thu, 27 Dec 2012 19:39:58 -0500 (EST) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 096EC3EE0D1 for ; Fri, 28 Dec 2012 09:39:57 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id DD91645DEBB for ; Fri, 28 Dec 2012 09:39:56 +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 BB1AE45DEB7 for ; Fri, 28 Dec 2012 09:39:56 +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 ABDE41DB8042 for ; Fri, 28 Dec 2012 09:39:56 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 5FB1B1DB803F for ; Fri, 28 Dec 2012 09:39:56 +0900 (JST) Message-ID: <50DCEA3D.1030501@jp.fujitsu.com> Date: Fri, 28 Dec 2012 09:39:25 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 Subject: Re: [PATCH V3 2/8] Make TestSetPageDirty and dirty page accounting in one func References: <1356455919-14445-1-git-send-email-handai.szj@taobao.com> <1356456156-14535-1-git-send-email-handai.szj@taobao.com> In-Reply-To: <1356456156-14535-1-git-send-email-handai.szj@taobao.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Sha Zhengju Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, dchinner@redhat.com, mhocko@suse.cz, akpm@linux-foundation.org, gthelen@google.com, fengguang.wu@intel.com, glommer@parallels.com, Sha Zhengju (2012/12/26 2:22), Sha Zhengju wrote: > From: Sha Zhengju > > Commit a8e7d49a(Fix race in create_empty_buffers() vs __set_page_dirty_buffers()) > extracts TestSetPageDirty from __set_page_dirty and is far away from > account_page_dirtied. But it's better to make the two operations in one single > function to keep modular. So in order to avoid the potential race mentioned in > commit a8e7d49a, we can hold private_lock until __set_page_dirty completes. > There's no deadlock between ->private_lock and ->tree_lock after confirmation. > It's a prepare patch for following memcg dirty page accounting patches. > > > Here is some test numbers that before/after this patch: > Test steps(Mem-4g, ext4): > drop_cache; sync > fio (ioengine=sync/write/buffered/bs=4k/size=1g/numjobs=2/group_reporting/thread) > > We test it for 10 times and get the average numbers: > Before: > write: io=2048.0MB, bw=254117KB/s, iops=63528.9 , runt= 8279msec > lat (usec): min=1 , max=742361 , avg=30.918, stdev=1601.02 > After: > write: io=2048.0MB, bw=254044KB/s, iops=63510.3 , runt= 8274.4msec > lat (usec): min=1 , max=856333 , avg=31.043, stdev=1769.32 > > Note that the impact is little(<1%). > > > Signed-off-by: Sha Zhengju > Reviewed-by: Michal Hocko Acked-by: KAMEZAWA Hiroyuki Hmm,..this change should be double-checked by vfs, I/O guys... increasing hold time of mapping->private_lock doesn't affect performance ? -- 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