From owner-freebsd-hackers Fri Jan 31 20:55:14 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id UAA03952 for hackers-outgoing; Fri, 31 Jan 1997 20:55:14 -0800 (PST) Received: from hydrogen.nike.efn.org (metriclient-11.uoregon.edu [128.223.172.11]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id UAA03945 for ; Fri, 31 Jan 1997 20:55:07 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by hydrogen.nike.efn.org (8.8.4/8.8.4) with SMTP id UAA28220; Fri, 31 Jan 1997 20:53:37 -0800 (PST) Date: Fri, 31 Jan 1997 20:53:37 -0800 (PST) From: John-Mark Gurney Reply-To: John-Mark Gurney To: Terry Lambert cc: hackers@freefall.freebsd.org Subject: Re: performance puzzler In-Reply-To: <199701311738.KAA03009@phaeton.artisoft.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Fri, 31 Jan 1997, Terry Lambert wrote: > > The puzzling thing comes when I try to run the test at home on my AMD > > 486-120, running 2.1.0-RELEASE. It runs the test in 0.6 milliseconds!! > > Divide each clock speed by increasing integer values starting with 1 > until the result is less than or equal to 33. This is your max bus > speed possible for the system. An easy way to do this is magnitude > based arithmatic (yes, I own a slide-rule): > > exp(log(120)%log(33)) = 30 > exp(log(66)%log(33)) = 33 > > Your bus on the 120 is 3MHz slower than the bus on the 66. What you > are doing is not I/O bound, it is CPU bound. umm... this usually isn't true... most of the non 33mhz bus speeds (for 486 based chips) are actually 40 mhz or 50mhz... the amd-486/120dx4 is actually a 40mhz bus multiplied by 3... it's kinda like the Intel 486/100dx4... the chip is actually 3x bus speed (33mhz)... like AMD makes a 5x86/133... if you get the ADZ version you can usually over clock it to a 160... 40mhz x 4... the reason being is the ADZ's encasing is rated at 85C unlike the ADW that's only 55C... sure it's taking a chance, but it's a nice boost on a vlb based machine :)... John-Mark gurney_j@efn.org http://resnet.uoregon.edu/~gurney_j/ Modem/FAX: (541) 683-6954 (FreeBSD Box) Live in Peace, destroy Micro$oft, support free software, run FreeBSD (unix)