From owner-freebsd-alpha@FreeBSD.ORG Fri Jan 14 18:06:01 2005 Return-Path: Delivered-To: freebsd-alpha@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 18B7316A4CE for ; Fri, 14 Jan 2005 18:06:01 +0000 (GMT) Received: from mail27.sea5.speakeasy.net (mail25.sea5.speakeasy.net [69.17.117.27]) by mx1.FreeBSD.org (Postfix) with ESMTP id C47BA43D45 for ; Fri, 14 Jan 2005 18:06:00 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 23218 invoked from network); 14 Jan 2005 18:06:00 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) AES256-SHA encrypted SMTP for ; 14 Jan 2005 18:06:00 -0000 Received: from [10.50.40.231] (gw1.twc.weather.com [216.133.140.1]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id j0EI5ruJ042325; Fri, 14 Jan 2005 13:05:54 -0500 (EST) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: freebsd-alpha@FreeBSD.org Date: Fri, 14 Jan 2005 10:43:00 -0500 User-Agent: KMail/1.6.2 References: <16866.32790.398095.651691@canoe.dclg.ca> <20050114002651.GD29445@dragon.nuxi.com> <20050114074336.GA97061@freebie.xs4all.nl> In-Reply-To: <20050114074336.GA97061@freebie.xs4all.nl> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200501141043.00568.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx Subject: Re: processor type. X-BeenThere: freebsd-alpha@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Porting FreeBSD to the Alpha List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Jan 2005 18:06:01 -0000 On Friday 14 January 2005 02:43 am, Wilko Bulte wrote: > On Thu, Jan 13, 2005 at 04:26:51PM -0800, David O'Brien wrote.. > > > On Mon, Jan 10, 2005 at 08:16:06AM -0500, David Gilbert wrote: > > > I see in the compiler lines crawling by that gcc is asked to optimize > > > for 'EV5' while being compatible with 'EV4'. My Alpha is an EV4 --- > > > I'm wondering if I would see better performance with a different flag > > > there, but the gcc manual doesn't even acknowledge the existance of > > > the options that are in use, let alone the available options. > > > > It doens't??? > > > > >From /usr/share/mk/bsd.cpu.mk: > > > > . elif ${MACHINE_ARCH} == "alpha" > > _CPUCFLAGS = -mcpu=ev4 -mtune=ev5 > > > > http://gcc.gnu.org/onlinedocs/gcc-3.4.3/gcc/DEC-Alpha-Options.html#DEC-Al > >pha-Options clearly tells: > > > > -mcpu=cpu_type > > Set the instruction set and instruction scheduling parameters for > > machine type cpu_type. You can specify either the EV style name or > > the corresponding chip number. GCC supports scheduling parameters for > > the EV4, EV5 and EV6 family of processors. > > > > -mtune=cpu_type > > Set only the instruction scheduling parameters for machine type > > cpu_type. The instruction set is not changed. > > > > > > That said, you should remove the -mtune=ev5 or change it to -mtune=ev4. > > My guess is you won't notice a difference, but this this change will > > produce the best code for your machine. > > Any idea how drastic -mtune=ev6 would change things on a DS10 (to name > a random box ;-) ? > > Am I correct in assuming that -mcpu=ev4 will result in not using the BWX > etc of the newer CPUs? And that -mcpu=ev6 will result in code that does > not run on anything older than EV6 due to missing instructions etc? Yes. Note that setting CPUTYPE in make.conf gets all the right flags set for you automagically. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org