From owner-freebsd-questions Wed Apr 18 3: 7:37 2001 Delivered-To: freebsd-questions@freebsd.org Received: from guru.mired.org (okc-65-26-235-186.mmcable.com [65.26.235.186]) by hub.freebsd.org (Postfix) with SMTP id 8F7F237B422 for ; Wed, 18 Apr 2001 03:07:34 -0700 (PDT) (envelope-from mwm@mired.org) Received: (qmail 16632 invoked by uid 100); 18 Apr 2001 10:07:32 -0000 From: Mike Meyer MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15069.26468.279995.42083@guru.mired.org> Date: Wed, 18 Apr 2001 05:07:32 -0500 To: "Jeremiah Gowdy" Cc: questions@freebsd.org Subject: Re: the AMD factor in FreeBSD In-Reply-To: <64762482@toto.iv> X-Mailer: VM 6.90 under 21.1 (patch 14) "Cuyahoga Valley" XEmacs Lucid X-face: "5Mnwy%?j>IIV\)A=):rjWL~NB2aH[}Yq8Z=u~vJ`"(,&SiLvbbz2W`;h9L,Yg`+vb1>RG% *h+%X^n0EZd>TM8_IB;a8F?(Fb"lw'IgCoyM.[Lg#r\ Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Jeremiah Gowdy types: > As for the AMD+SMP vs Intel+SMP, I can't say regarding the FreeBSD support, > however, AMD's SMP is supposed to be far faster than Intel's because it has > a Point-to-Point bus for the SMP connection, meaning _each_ CPU has a > dedicated 200mhz (100mhz DDR) connection to the bus, when on an Intel SMP > motherboard the two or more cpus will share the same 100mhz bus. That means > on a 4 way SMP Intel system, each cpu will get an effective 25mhz access to > the bus under full load in theory. By the same theory, AMD cpus would each > have their own 200mhz dedicated connection to the bus, even in an 8 cpu > setup. You're talking about the speed of the connection to the bus, without talking about the speed of the bus. If the bus in question is 100MHz, then in any 4-cpu system at full load, each cpu will have at most 25MHz on the bus, never mind that their connection to the bus is 200MHz. So you've just spent 4 times the amount on cpu bus hardware for no gain in performance. If the bus is 133MHz, then each cpu can get 33MHz on the bus on a loaded system, and the shared connection to the bus causes a problem. There may be something obvious I've overlooked - in which case, I'm sure I'll be told about it. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message