From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id n5GM4ohI181220 for ; Tue, 16 Jun 2009 17:04:51 -0500 Received: from mail.sandeen.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 1C0B4126A086 for ; Tue, 16 Jun 2009 15:05:14 -0700 (PDT) Received: from mail.sandeen.net (sandeen.net [209.173.210.139]) by cuda.sgi.com with ESMTP id aMWmDScO8pGwFVNP for ; Tue, 16 Jun 2009 15:05:14 -0700 (PDT) Message-ID: <4A38171A.4080500@sandeen.net> Date: Tue, 16 Jun 2009 17:05:14 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: Re: XFS Preallocate using ALLOCSP References: <24042506.post@talk.nabble.com> <4A3712BF.7030101@sandeen.net> <8770d98c0906152344p185533a9rc144a5667d13d2de@mail.gmail.com> <4A37B744.9030301@sandeen.net> <0B774481-16A5-42FC-89C3-91096E59E861@sgi.com> <8770d98c0906161028j1cc5cbadl49d30092fddf3dbe@mail.gmail.com> <8770d98c0906161442t634467bxe8b0f5c32b49502e@mail.gmail.com> In-Reply-To: <8770d98c0906161442t634467bxe8b0f5c32b49502e@mail.gmail.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Smit Shah Cc: linux-xfs@oss.sgi.com Smit Shah wrote: > On 6/16/09, Felix Blyakher wrote: >>> but the write performance is going to suffer. >> It's not clear why it should. Not doing preallocation doesn't >> mean that there is no inode updates with every write. Why >> would extent conversion be more expensive that creating the >> space (extent) and updating the inode size for every write? >> It'd interesting to reproduce your results. Any details on >> your tests and the iometer usage? > > Since fallocate uses the RESVSP cmd for xfs. And as given given for > RESVSP in man page for xfsctl > If the XFS filesystem is configured to flag unwritten file extents, > performance will be negatively affected when writing to preallocated > space, since extra filesystem transactions are required to convert > extent flags on the range of the file written. And ext4 must do basically the same thing, as would any fs that flags unwritten extents. ext4 may convert more at a time, though, rather than leaving "fragmented" written/unwritten/written/unwritten regions. -Eric _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs