From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH RFC] nilfs2: continuous snapshotting file system Date: Thu, 21 Aug 2008 08:51:31 -0400 Message-ID: <1219323091.7854.45.camel@think.oraclecorp.com> References: <20080820004326.519405a2.akpm@linux-foundation.org> <200808201613.AA00212@capsicum.lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Ryusuke Konishi , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Szabolcs Szakacsits Return-path: Received: from rgminet01.oracle.com ([148.87.113.118]:59200 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753902AbYHUMwl (ORCPT ); Thu, 21 Aug 2008 08:52:41 -0400 In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, 2008-08-21 at 00:25 +0300, Szabolcs Szakacsits wrote: > On Thu, 21 Aug 2008, Ryusuke Konishi wrote: > > >> Some impressive benchmark results on SSD are shown in [3], > > > > > >heh. It wipes the floor with everything, including btrfs. > > It seems the benchmark was done over half year ago. It's questionable how > relevant today the performance comparison is with actively developed file > systems ... > I'd expect that nilfs continues to win postmark. Btrfs splits data and metadata into different parts of the disk, so at best btrfs is going to produce two streams of writes into the SSD while nilfs is doing one. Most consumer ssds still benefit from huge writes, and so nilfs is pretty optimal in that case. The main benefit of the split for btrfs is being able to have different duplication policies for metadata and data, and faster fsck times because the metadata is more compact. Over time that may prove less relevant on SSD, and changing it in btrfs is just flipping a few bits during allocation. -chris