From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [PATCH 0/6] writeback time order/delay fixes take 3 Date: Fri, 24 Aug 2007 21:55:04 +0800 Message-ID: <387963704.05674@ustc.edu.cn> References: <386910467.21100@ustc.edu.cn> <20070821202314.335e86ec@think.oraclecorp.com> <20070822011841.GA8090@mail.ustc.edu.cn> <20070823023306.GM61154114@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Chris Mason , Andrew Morton , Ken Chen , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe To: David Chinner Return-path: Received: from smtp.ustc.edu.cn ([202.38.64.16]:35697 "HELO ustc.edu.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1752956AbXHXNzI (ORCPT ); Fri, 24 Aug 2007 09:55:08 -0400 Message-ID: <20070824135504.GA9029@mail.ustc.edu.cn> Content-Disposition: inline In-Reply-To: <20070823023306.GM61154114@sgi.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Aug 23, 2007 at 12:33:06PM +1000, David Chinner wrote: > On Wed, Aug 22, 2007 at 09:18:41AM +0800, Fengguang Wu wrote: > > On Tue, Aug 21, 2007 at 08:23:14PM -0400, Chris Mason wrote: > > Notes: > > (1) I'm not sure inode number is correlated to disk location in > > filesystems other than ext2/3/4. Or parent dir? > > The correspond to the exact location on disk on XFS. But, XFS has it's > own inode clustering (see xfs_iflush) and it can't be moved up > into the generic layers because of locking and integration into > the transaction subsystem. > > > (2) It duplicates some function of elevators. Why is it necessary? > > The elevators have no clue as to how the filesystem might treat adjacent > inodes. In XFS, inode clustering is a fundamental feature of the inode > reading and writing and that is something no elevator can hope to > acheive.... Thank you. That explains the linear write curve(perfect!) in Chris' graph. I wonder if XFS can benefit any more from the general writeback clustering. How large would be a typical XFS cluster? -fengguang From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [PATCH 0/6] writeback time order/delay fixes take 3 Date: Fri, 24 Aug 2007 21:55:04 +0800 Message-ID: <20070824135504.GA9029__4576.59745957262$1187963748$gmane$org@mail.ustc.edu.cn> References: <386910467.21100@ustc.edu.cn> <20070821202314.335e86ec@think.oraclecorp.com> <20070822011841.GA8090@mail.ustc.edu.cn> <20070823023306.GM61154114@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Chris Mason , Andrew Morton , Ken Chen , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jens Axboe To: David Chinner Return-path: Message-ID: <20070824135504.GA9029@mail.ustc.edu.cn> Content-Disposition: inline In-Reply-To: <20070823023306.GM61154114@sgi.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Aug 23, 2007 at 12:33:06PM +1000, David Chinner wrote: > On Wed, Aug 22, 2007 at 09:18:41AM +0800, Fengguang Wu wrote: > > On Tue, Aug 21, 2007 at 08:23:14PM -0400, Chris Mason wrote: > > Notes: > > (1) I'm not sure inode number is correlated to disk location in > > filesystems other than ext2/3/4. Or parent dir? > > The correspond to the exact location on disk on XFS. But, XFS has it's > own inode clustering (see xfs_iflush) and it can't be moved up > into the generic layers because of locking and integration into > the transaction subsystem. > > > (2) It duplicates some function of elevators. Why is it necessary? > > The elevators have no clue as to how the filesystem might treat adjacent > inodes. In XFS, inode clustering is a fundamental feature of the inode > reading and writing and that is something no elevator can hope to > acheive.... Thank you. That explains the linear write curve(perfect!) in Chris' graph. I wonder if XFS can benefit any more from the general writeback clustering. How large would be a typical XFS cluster? -fengguang