From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: [PATCH 1/4] md: Factor out RAID6 algorithms into lib/ Date: Fri, 17 Jul 2009 11:35:46 -0400 Message-ID: <4A609A52.7070506@redhat.com> References: <1247494302.19180.268.camel@macbook.infradead.org> <4A5F6590.9000006@zytor.com> <4A608913.1060808@redhat.com> <4A6096A0.5050501@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A6096A0.5050501@zytor.com> Sender: linux-raid-owner@vger.kernel.org To: "H. Peter Anvin" Cc: Dan Williams , David Woodhouse , chris.mason@oracle.com, linux-btrfs@vger.kernel.org, neilb@suse.de, linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/17/2009 11:20 AM, H. Peter Anvin wrote: > Ric Wheeler wrote: >> >> Worth sharing a pointer to a really neat set of papers that describe >> open source friendly RAID6 and erasure encoding algorithms that were >> presented last year and this at FAST: >> >> http://www.cs.utk.edu/~plank/plank/papers/papers.html >> >> If I remember correctly, James Plank's papers also have implemented >> and benchmarked the various encodings, >> > > I have seen the papers; I'm not sure it really makes that much > difference. One of the things that bugs me about these papers is that he > compares to *his* implementation of my optimizations, but not to my > code. In real life implementations, on commodity hardware, we're limited > by memory and disk performance, not by CPU utilization. > > -hpa > Fair enough - I thought that his coverage of the other open source friendly encodings beyond RAID6 was actually quite interesting. If you have specifics that you found unconvincing in his work, I am pretty sure that he would be delighted to hear from you first hand. James seemed to me to be very reasonable and very much a pro-Linux academic, so I would love to be able to get him and his grad students aligned in a useful way for us :-) ric