From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 1/4] md: Factor out RAID6 algorithms into lib/ Date: Wed, 29 Jul 2009 11:20:58 -0700 Message-ID: <4A70930A.1050006@zytor.com> References: <1247494302.19180.268.camel@macbook.infradead.org> <4A5F6590.9000006@zytor.com> <4A608913.1060808@redhat.com> <4A6096A0.5050501@zytor.com> <4A609A52.7070506@redhat.com> <4A609B72.2010901@zytor.com> <4A609CFA.2060707@redhat.com> <4A609D8D.8050501@zytor.com> <1247918016.22313.138.camel@macbook.infradead.org> <4A61C3D9.6020200@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org To: Alex Elsayed Cc: linux-raid@vger.kernel.org, linux-btrfs@vger.kernel.org List-Id: linux-raid.ids On 07/18/2009 11:52 AM, Alex Elsayed wrote: > Alex Elsayed wrote: > >> H. Peter Anvin wrote: >>> implementation in Java, called "Jerasure".) Implementability using real >>> array instruction sets is key to decent performance. >> Actually, it is made clear in the paper that Jerasure is written as a C >> library, and Clearsafe is the only Java implementation. Don't let the name >> fool you. ;D > And again, I make a typo. s/Clearsafe/Cleversafe/. > It's still their own implementation of poor quality. That it is poor quality shows in the numbers, which are dramatically lower than the actual Linux implementation -- by an order of magnitude or more. In other words, they build a strawman and knock it down. The actual Linux implementation blasts any of the numbers they have in their paper, which I presume means they haven't optimized any of them. As such, all the numbers are meaningless. -hpa