From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 12 Sep 2001 14:09:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 12 Sep 2001 14:09:48 -0400 Received: from adsl-63-194-239-202.dsl.lsan03.pacbell.net ([63.194.239.202]:2302 "EHLO mmp-linux.matchmail.com") by vger.kernel.org with ESMTP id ; Wed, 12 Sep 2001 14:09:36 -0400 Date: Wed, 12 Sep 2001 11:09:50 -0700 From: Mike Fedyk To: linux-kernel@vger.kernel.org Subject: Re: Duron kernel crash (i686 works) Message-ID: <20010912110950.D25683@mikef-linux.matchmail.com> Mail-Followup-To: linux-kernel@vger.kernel.org In-Reply-To: <2415359415.20010912164800@port.imtp.ilyichevsk.odessa.ua> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2415359415.20010912164800@port.imtp.ilyichevsk.odessa.ua> User-Agent: Mutt/1.3.20i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 12, 2001 at 04:48:00PM +0300, VDA wrote: > >> A better way to do it is to bencmark several routines at > >> startup time and pick the best one. It is done now > >> for RAID xor'ing routine. > AC> Not in this case. It is Athlon specific code. It was fine > AC> tuned when it was written > Yes, but sometimes we have routines which perform > differently on different CPUs. See inslude/asm-i386/string.h > and string-486.h: on Pentium rep movsd is faster, on 386 unrolled > loop is faster... so optimal routine can be picked only at runtime. > CPU-specific routines can compete in such runtime benchmark > too when proper processor is detected - see how KNI-specific > RAID xor routine does that. Hmm, just how far do you want to take that? Compile in all of the optimizations and test which is fastest on each processor at startup? Hmm, that might not be a bad idea for dev kernels, as it might show optimization problems on certain processors...