From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267678AbUHJTvh (ORCPT ); Tue, 10 Aug 2004 15:51:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267682AbUHJTvg (ORCPT ); Tue, 10 Aug 2004 15:51:36 -0400 Received: from hera.kernel.org ([63.209.29.2]:43936 "EHLO hera.kernel.org") by vger.kernel.org with ESMTP id S267685AbUHJTvf (ORCPT ); Tue, 10 Aug 2004 15:51:35 -0400 To: linux-kernel@vger.kernel.org From: hpa@zytor.com (H. Peter Anvin) Subject: Re: AES assembler optimizations Date: Tue, 10 Aug 2004 19:51:29 +0000 (UTC) Organization: Transmeta Corporation, Santa Clara CA Message-ID: References: <2riR3-7U5-3@gated-at.bofh.it> <1092067328.4332.40.camel@orion> <20040809171231.GG2716@mea-ext.zmailer.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Trace: terminus.zytor.com 1092167489 13233 127.0.0.1 (10 Aug 2004 19:51:29 GMT) X-Complaints-To: news@terminus.zytor.com NNTP-Posting-Date: Tue, 10 Aug 2004 19:51:29 +0000 (UTC) X-Newsreader: trn 4.0-test76 (Apr 2, 2001) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Followup to: <20040809171231.GG2716@mea-ext.zmailer.org> By author: Matti Aarnio In newsgroup: linux.dev.kernel > > Usage of MMX inside the Linux kernel is like the usage of FP inside > the Linux kernel: Can be done after jumping complex hoops, BUT NOT > RECOMMENDED... (MMX in intertwined with FP hardware, after all.) > > You have to do lots of the MMXes in order to win after amortizing those > necessary hoops... RAID-5 code does XOR via MMX code, under some > conditions. ... where that happens to become a win. > It's not really that hard, you just have to have enough work to amortize it over. The two metrics are: how much work do you get per call, and how much work do you get before the next schedule(). -hpa