From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id pBTD8k0s006095 for ; Thu, 29 Dec 2011 07:08:46 -0600 Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com [209.85.212.181]) by cuda.sgi.com with ESMTP id T3KDwcsMf9W6qeia for ; Thu, 29 Dec 2011 05:08:44 -0800 (PST) Received: by wibhq2 with SMTP id hq2so7506155wib.26 for ; Thu, 29 Dec 2011 05:08:44 -0800 (PST) Message-ID: <4efc665b.d139e30a.2f32.fffff97a@mx.google.com> Date: Thu, 29 Dec 2011 13:10:49 +0000 From: "amit.sahrawat83@gmail.com" Subject: Preallocation with direct IO? MIME-Version: 1.0 Reply-To: amit.sahrawat83@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: "hch@infradead.org" , "david@fromorbit.com" , "xfs@oss.sgi.com" Hi, I am using a test setup which is doing write using multiple threads using direct IO. The buffer size which is used to write is 512KB. After continously running this for long duration - i observe that number of extents in each file is getting huge(2K..4K..). I observed that each extent is of 512KB(aligned to write buffer size). I wish to have low number of extents(i.e, reduce fragmentation)... In case of buffered IO- preallocation works good alongwith the mount option 'allocsize'. Is there anything which can be done for Direct IO? Please advice for reducing fragmentation with direct IO. Thanks & Regards, Amit Sahrawat Sent from my Nokia phone _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs