From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: Allocation strategy - dynamic zone for small files Date: Tue, 14 Nov 2006 11:23:56 -0700 Message-ID: <20061114182356.GP6012@schatzie.adilger.int> References: <20061113193816.GA31700@filer.fsl.cs.sunysb.edu> <20061113235749.GK6012@schatzie.adilger.int> <1163470783.24187.11.camel@kleikamp.austin.ibm.com> <20061114131521.GA30630@wohnheim.fh-wedel.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: =?iso-8859-1?Q?J=F6rn?= Engel , Dave Kleikamp , Bryan Henderson , Josef Sipek , avishay , linux-fsdevel@vger.kernel.org Return-path: Received: from mail.clusterfs.com ([206.168.112.78]:11153 "EHLO mail.clusterfs.com") by vger.kernel.org with ESMTP id S966256AbWKNSX7 (ORCPT ); Tue, 14 Nov 2006 13:23:59 -0500 To: Ihar `Philips` Filipau Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Nov 14, 2006 14:41 +0100, Ihar `Philips` Filipau wrote: > More I'm thinking about that, more I'm convinced that some sort of > compromise is required. E.g. file system with 2/more cluster sizes: > for example 4k for small/medium files, 64+k cluster for large files. > Files of 100+MB sizes are not that rare anymore (home video/audio > processing now is affordable as never before). But on other side tiny > files like e.g. found in /etc or ~/.kde/* are not going to disappear > anytime soon. Well, current plan is that new allocator (mballoc + delalloc) from Alex Tomas will do efficient in-memory allocation of many contiguous blocks, and extents format will allow efficient on-disk storage of many contiguous blocks, so benefit of larger cluster size in disk format is minimal. Essentially, delaying the disk allocation until a file is large/complete (delalloc) and then using a buddy allocator in memory to get contiguous chunks of disk is better than hard 64K+ cluster because it avoids internal fragmentation and allows much more optimal/efficient placement than just a factor of 16 reduction in the block count. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.