From: Andreas Dilger Subject: Re: [PATCH -V3 04/11] ext4: Add percpu dirty block accounting. Date: Sat, 11 Oct 2008 15:10:07 -0600 Message-ID: <20081011211007.GB2009@webber.adilger.int> References: <1219850916-8986-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1219850916-8986-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1219850916-8986-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1219850916-8986-4-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <48EE6D43.7070404@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7BIT Cc: "Aneesh Kumar K.V" , cmm@us.ibm.com, tytso@mit.edu, linux-ext4@vger.kernel.org, Alex Zhuravlev To: Eric Sandeen Return-path: Received: from sca-es-mail-1.Sun.COM ([192.18.43.132]:60886 "EHLO sca-es-mail-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760262AbYJKVKW (ORCPT ); Sat, 11 Oct 2008 17:10:22 -0400 Received: from fe-sfbay-10.sun.com ([192.18.43.129]) by sca-es-mail-1.sun.com (8.13.7+Sun/8.12.9) with ESMTP id m9BLAJNa009296 for ; Sat, 11 Oct 2008 14:10:20 -0700 (PDT) Received: from conversion-daemon.fe-sfbay-10.sun.com by fe-sfbay-10.sun.com (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) id <0K8L00J01ET09D00@fe-sfbay-10.sun.com> (original mail from adilger@sun.com) for linux-ext4@vger.kernel.org; Sat, 11 Oct 2008 14:10:19 -0700 (PDT) In-reply-to: <48EE6D43.7070404@redhat.com> Content-disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: On Oct 09, 2008 15:44 -0500, Eric Sandeen wrote: > Somehow, though, we seem to be allocating only 2048 blocks at a time > (haven't worked out why, yet - this also seems problematic) - but at any > rate, losing (32767-2048) blocks in each loop from fallocate seems to be > causing this space loss and eventual ENOSPC. I believe the 2048-block (8MB) allocation limit is imposed by mballoc to avoid scanning the whole filesystem looking for huge chunks of free disk. That said, it would be nice if there IS lots of free space that this is allocated optimistically if possible. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.