From owner-freebsd-hackers Thu May 16 11:32:02 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id LAA22528 for hackers-outgoing; Thu, 16 May 1996 11:32:02 -0700 (PDT) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id LAA22477 for ; Thu, 16 May 1996 11:32:00 -0700 (PDT) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id LAA17550; Thu, 16 May 1996 11:27:35 -0700 From: Terry Lambert Message-Id: <199605161827.LAA17550@phaeton.artisoft.com> Subject: Re: EDO & Memory latency To: narvi@haldjas.folklore.ee (Narvi) Date: Thu, 16 May 1996 11:27:35 -0700 (MST) Cc: terry@lambert.org, babkin@hq.icb.chel.su, hackers@FreeBSD.org In-Reply-To: from "Narvi" at May 16, 96 09:28:15 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@FreeBSD.org X-Loop: FreeBSD.org Precedence: bulk > > > I have just tried lmbench and the numbers it gives are looking > > > slightly strange for me. It shows memory latency upto 500ns while > > > I have 60-ns EDO memory in a Pentium/75 box. Okay, its external > > > clock is 25MHz, this gives 40ns, one wait state, it gives another 40ns, > > > it gives 80ns, but why the overhead is over 400ns ? > > > > 25 * 3 = 75 > > > > Multiply access latency by 3. > > Contrary to what some prefer to think, Pentium 75 run on the external > speed of 50 Mhz - 1.5*50=75. So how about looking the figures over once > more time? Was this supposed to be a memory bus or a data bus speed? PCI can't run faster than 33 -- on a 75, that means 25. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.