Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754446AbZCUCbj (ORCPT ); Fri, 20 Mar 2009 22:31:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753430AbZCUCb1 (ORCPT ); Fri, 20 Mar 2009 22:31:27 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53841 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753150AbZCUCb0 (ORCPT ); Fri, 20 Mar 2009 22:31:26 -0400 Message-ID: <49C45159.8020503@zytor.com> Date: Fri, 20 Mar 2009 19:30:49 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Ilya Yanok CC: "H. Peter Anvin" , "Williams, Dan J" , "linux-raid@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "neilb@suse.de" , "Sosnowski, Maciej" , Yuri Tikhonov Subject: Re: [PATCH 06/13] async_tx: add support for asynchronous GF multiplication References: <20090318191248.20375.40560.stgit@dwillia2-linux.ch.intel.com> <20090318192046.20375.89854.stgit@dwillia2-linux.ch.intel.com> <49C26D91.10804@intel.com> <49C41C1E.4060401@zytor.com> <49C4201A.5060905@emcraft.com> <49C425F5.8060309@intel.com> <49C42F99.5010700@emcraft.com> In-Reply-To: <49C42F99.5010700@emcraft.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 31 Ilya Yanok wrote: > > async_gen_syndrome() takes element of GF^n(256) and returns result of > scalar multiplication of it with constant ({01}, {02}, {02}^2, ..., > {02}^n) vector. For any n (which would mean any GF field)? In that case, that is generic scalar-vector multiplication... > async_pq() takes two vectors from GF^n(256) and returns their scalar > multiplication. > > We need async_pq() function if we want to offload D_x = A * (P + P_{xy}) > + B * (Q + Q_{xy}) part of DD recovery and D_x = (Q + Q_x) * g^{-x} part > of DP recovery. No, you don't. A and B (and g^{-x}) are scalars, meaning they're the same for every element. This is simpler to do. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/