From owner-freebsd-alpha@FreeBSD.ORG Fri Jan 14 07:43:40 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 3886016A4CE for ; Fri, 14 Jan 2005 07:43:40 +0000 (GMT) Received: from smtp-vbr4.xs4all.nl (smtp-vbr4.xs4all.nl [194.109.24.24]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6305443D39 for ; Fri, 14 Jan 2005 07:43:39 +0000 (GMT) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (freebie.xs4all.nl [213.84.32.253]) by smtp-vbr4.xs4all.nl (8.12.11/8.12.11) with ESMTP id j0E7hbwA078102 for ; Fri, 14 Jan 2005 08:43:37 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (localhost [127.0.0.1]) by freebie.xs4all.nl (8.13.1/8.12.9) with ESMTP id j0E7hbfw098989 for ; Fri, 14 Jan 2005 08:43:37 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: (from wb@localhost) by freebie.xs4all.nl (8.13.1/8.13.1/Submit) id j0E7hbsm098988 for freebsd-alpha@freebsd.org; Fri, 14 Jan 2005 08:43:37 +0100 (CET) (envelope-from wb) Date: Fri, 14 Jan 2005 08:43:37 +0100 From: Wilko Bulte To: freebsd-alpha@freebsd.org Message-ID: <20050114074336.GA97061@freebie.xs4all.nl> References: <16866.32790.398095.651691@canoe.dclg.ca> <20050114002651.GD29445@dragon.nuxi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050114002651.GD29445@dragon.nuxi.com> X-OS: FreeBSD 4.11-RC2 User-Agent: Mutt/1.5.6i X-Virus-Scanned: by XS4ALL Virus Scanner 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 07:43:40 -0000 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-Alpha-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? W/ -- Wilko Bulte wilko@FreeBSD.org