From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 06/13] async_tx: add support for asynchronous GF multiplication Date: Sat, 21 Mar 2009 12:15:12 -0700 Message-ID: <49C53CC0.5060303@zytor.com> 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> <49C45159.8020503@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Dan Williams Cc: Ilya Yanok , "H. Peter Anvin" , "linux-raid@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "neilb@suse.de" , "Sosnowski, Maciej" , Yuri Tikhonov List-Id: linux-raid.ids Dan Williams wrote: >> >> 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. > > Understood. However this routine also needs to cover the non-generic > and non-constant case where we have a separate coefficient per > element. I suppose it could scan the coefficient list to see if it > can bypass the 2-dimensional lookup multiply. At the very least we > need something like the following, because async_pq is really only a > helper routine for async_r6recov.c which knows how to avoid the > synchronous path. > Why does it? I don't see why you'd need to cover the vector-vector case at all, since it doesn't appear anywhere in the algorithms. Certainly going backwards from a vector-vector set to derive if you can do a scalar-vector multiply when you should have known that in the first place is not really useful. > > Looking closer, the only other caller, async_pq_zero_sum, can be > deleted because it has no users. So async_pq can become a static > routine in async_r6recov. > That's another issue entirely, of course :) -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.