From owner-freebsd-fs@FreeBSD.ORG Tue Mar 15 19:59:43 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D9D631065675 for ; Tue, 15 Mar 2011 19:59:43 +0000 (UTC) (envelope-from giffunip@tutopia.com) Received: from nm30.bullet.mail.sp2.yahoo.com (nm30.bullet.mail.sp2.yahoo.com [98.139.91.100]) by mx1.freebsd.org (Postfix) with SMTP id B651B8FC12 for ; Tue, 15 Mar 2011 19:59:43 +0000 (UTC) Received: from [98.139.91.70] by nm30.bullet.mail.sp2.yahoo.com with NNFMP; 15 Mar 2011 19:59:43 -0000 Received: from [98.139.91.39] by tm10.bullet.mail.sp2.yahoo.com with NNFMP; 15 Mar 2011 19:59:43 -0000 Received: from [127.0.0.1] by omp1039.mail.sp2.yahoo.com with NNFMP; 15 Mar 2011 19:59:43 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 322079.84647.bm@omp1039.mail.sp2.yahoo.com Received: (qmail 68451 invoked by uid 60001); 15 Mar 2011 19:59:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1300219183; bh=QMT0xpvgvafj8upaxCwrKHzEh8ibZcda78X/zPhxaVs=; h=Message-ID:X-YMail-OSG:Received:X-RocketYMMF:X-Mailer:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type; b=gdVh/9xoD1iYbBG9k/pkKJPP2iNXFzNKtyTOCYljmYuc+Bri8JuS4mg95gFZa10d8cWZ59H/yHZSdBCQ/yHkkXMeSEvSbjvk6qdprqFgDK6AgxehuNYBZaxCyd1jgoxUi5iZI6BmOBUv9RQYP6TWgiAFOXFPDzy+m5OHpO4DvdI= Message-ID: <995608.55186.qm@web113511.mail.gq1.yahoo.com> X-YMail-OSG: OWnEKcMVM1lK2oD8rhe3hLBtVw5xy4FWJZpjdNtf17NaQzM N4KudVm_ET0u_05RGDS6U0YuFLPtx2TlCQi5ts6bXVZWGkGLY1SqMjHNTwX0 ALQ1x0Wo2NBzXx.05Tk0LSP68G2LLUfoE3xsG9q8rJVeMckbGOwCady3kRyP L.u78qlz013GHzIMncAO.5z2NzFwY4WkRxCgq5D2aCFrOrJ00MNHWs6bkxgX ohT4IM_Nx33s3aKW6vBkxSeQi81MRHvMroc10LTwT7pm0_rUhKP4EaZhUx80 dtS8brZjKjAhovG1qhXQruv8o1CR2HMWoZOB9rFApZlwEzl430k0K5XB949R xsX78VfqbzuYIOW3.InP6KhhSGwOdM9cWC3enDS0JXq2l3USfPZzB.utFX9X uVHT9nxp2nEj2 Received: from [200.118.159.214] by web113511.mail.gq1.yahoo.com via HTTP; Tue, 15 Mar 2011 12:59:42 PDT X-RocketYMMF: giffunip X-Mailer: YahooMailClassic/11.4.20 YahooMailWebService/0.8.109.295617 Date: Tue, 15 Mar 2011 12:59:42 -0700 (PDT) From: "Pedro F. Giffuni" To: freebsd-fs@freebsd.org, gnehzuil In-Reply-To: <4D7F58C7.4060402@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Subject: Re: [ext2fs][patch] reallocblks X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: giffunip@tutopia.com List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Mar 2011 19:59:43 -0000 --- On Tue, 3/15/11, gnehzuil wrote: ... > Hi there, > > I have implemented reallocblks in ext2fs. I added some > structures in m_ext2fs to record cluster summary information > due to group descriptor has not a structure to record these > data in disk. So I implemented it in memory. The > implementation is almost the same to in ffs. > > I have done some simple benchmarks with dbench. This patch > can improve the performance a little. > I should mention here that this approach (used by FFS) has shown to be a little better than the reservation window preallocation in performance and is specially important to control fragmentation and filesystem aging: an area that hasn't been worked on very much on other filesystems (notably ext2/3/4). This is loosely related to, and reduces the need for, some other "features" planned in ext4 like delayed allocation, online defragmentation, preallocation and to some extent tailmerging. For more discussion on this topic from a non-BSD perspective, check out: http://www-stud.rbi.informatik.uni-frankfurt.de/~loizides/reiserfs/ I am really glad to see this feature in our ext2 implementation. so thanks Zheng for doing the hard work, and Google for sponsoring him. cheers, Pedro.