From: "Aneesh Kumar K.V" Subject: Re: delalloc and reservation. Date: Mon, 29 Oct 2007 20:03:23 +0530 Message-ID: <4725EF33.7050804@linux.vnet.ibm.com> References: <4725AF5B.1000300@linux.vnet.ibm.com> <4725F8E6.2050500@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , Eric Sandeen , Valerie Clement , Theodore Tso , Mingming Cao , linux-ext4 To: Alex Tomas Return-path: Received: from E23SMTP03.au.ibm.com ([202.81.18.172]:60643 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757990AbXJ2PF3 (ORCPT ); Mon, 29 Oct 2007 11:05:29 -0400 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.18.234]) by e23smtp03.au.ibm.com (8.13.1/8.13.1) with ESMTP id l9TEXw3s030644 for ; Tue, 30 Oct 2007 01:33:58 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l9TEXxkm2617344 for ; Tue, 30 Oct 2007 01:33:59 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l9TEXe0e017446 for ; Tue, 30 Oct 2007 01:33:41 +1100 In-Reply-To: <4725F8E6.2050500@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Alex Tomas wrote: > Hi, > > could you try the patch attached. it should fix the issue. the idea > was to align requests in order to help raid5-like setups. but somewhere > I lost one bit in mballoc: it should pre-allocate all crossed stripes, > but it didn't. > > as for discard, lustre doesn't use open/close for data, so discard-on-close > makes zero sense in our case. I'm not very positive whether we need to > drop preallocation on file close in case of delayed allocation as writeback > can be started while file is open and finish after close(2). > > mballoc by default doesn't give the particular layout only if i force small size to use inode preallocation i am hitting the problem. ie to change the below line in ext4_mb_group_or_file if (ac->ac_o_ex.fe_len >= sbi->s_mb_small_req) to if (ac->ac_o_ex.fe_len <= sbi->s_mb_small_req) Do you want to test the patch with this change ? We are observing the problem with delalloc and nomballoc. -aneesh