From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH 2/8 v3] ext4: add operations on extent status tree Date: Thu, 8 Nov 2012 18:21:23 -0500 Message-ID: <20121108232123.GP19977@thunk.org> References: <1351257825-3701-1-git-send-email-wenqing.lz@taobao.com> <1351257825-3701-3-git-send-email-wenqing.lz@taobao.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, jeff.liu@oracle.com, hughd@google.com, xiaoqiangnk@gmail.com, achender@linux.vnet.ibm.com, lczerner@redhat.com, Zheng Liu To: Zheng Liu Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:60144 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751425Ab2KHXVg (ORCPT ); Thu, 8 Nov 2012 18:21:36 -0500 Content-Disposition: inline In-Reply-To: <1351257825-3701-3-git-send-email-wenqing.lz@taobao.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Oct 26, 2012 at 09:23:39PM +0800, Zheng Liu wrote: > + * 3. performance analysis > + * -- overhead > + * 1. Apart from operations on a delayed extent tree, we need to > + * down_write(inode->i_data_sem) in delayed write path to maintain delayed > + * extent tree, this can have impact on parallel read-write and write-write Hi Zheng, I can fix this up, before I finalize your commit, but I just want to check. I believe this comment is out of date --- we are now using a r/w spinlock, i_es_lock, yes? Since we never hold the spinlock for very long, I would be surprised if this is going to be a scalability bottleneck (too bad Eric doesn't have access to the big SMP machine that he used to use to help us do our scalability testing, so we could check to be sure). - Ted