From owner-freebsd-newbies@FreeBSD.ORG Tue Apr 29 10:53:13 2003 Return-Path: Delivered-To: freebsd-newbies@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3FBF637B401 for ; Tue, 29 Apr 2003 10:53:13 -0700 (PDT) Received: from issv0171.isis.de (issv0171.isis.de [195.158.131.223]) by mx1.FreeBSD.org (Postfix) with SMTP id A2F6C43FA3 for ; Tue, 29 Apr 2003 10:53:11 -0700 (PDT) (envelope-from charlie@begeistert.org) Received: (qmail 19812 invoked by uid 1010); 29 Apr 2003 17:53:10 -0000 Received: from unknown (HELO wonderland.1051603270.fake) ([195.158.148.80]) (envelope-sender ) by mail.isis.de (qmail-ldap-1.03) with SMTP for ; 29 Apr 2003 17:53:10 -0000 Date: Tue, 29 Apr 2003 19:54:06 +0200 From: Charlie Clark In-Reply-To: <200304291029.49957.DavidJohnson@Siemens.com> Message-Id: <20030429195406.3583.17@wonderland.1051603270.fake> Mime-Version: 1.0 References: <20030429063543.GA888@home.arachne.cz> <200304291029.49957.DavidJohnson@Siemens.com> To: freebsd-newbies@freebsd.org User-Agent: Beam devel Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Subject: Re: kernel optimized for Athlon XP 1800+ X-BeenThere: freebsd-newbies@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Gathering place for new users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Apr 2003 17:53:13 -0000 On 2003-04-29 at 19:29:49 [+0200], Johnson David wrote: > Those CPU settings for the kernel are not for optimization. They're for > accessing functionality. If you run dmesg and look near the top, you'll > find that FreeBSD kernel is detecting your CPU as a "686-class CPU" > regardless. The kernel is not optimized because it's just too close to > the metal. Optimize it too much and it will break every time gcc changes > its optimizer ever so slightly. I'm just curious as to why someone would be so keen to optimise the kernel: the discussion seemed to be aimed at squeezing the last quantum of performance out of a specific processor. This isn't ever likely to be possible for a system that can run on different processors like FreeBSD at least my understanding is that portability comes at the cost of performance. The best way to optimise is to remove things you don't need then hand tweak the code, use a compiler that's optimised for the processor, ie. Intel rather than gcc and enable all the switches. But as was said - there is a separate mailing list for this. Charlie