From owner-freebsd-questions Tue Apr 6 21:56:46 1999 Delivered-To: freebsd-questions@freebsd.org Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (Postfix) with ESMTP id 8FD6614CC0 for ; Tue, 6 Apr 1999 21:56:39 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id OAA12350; Wed, 7 Apr 1999 14:24:39 +0930 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id OAA13271; Wed, 7 Apr 1999 14:24:36 +0930 (CST) Message-ID: <19990407142436.D2142@lemis.com> Date: Wed, 7 Apr 1999 14:24:36 +0930 From: Greg Lehey To: Darren Pilgrim , unknown@riverstyx.net Cc: Mark Ovens , Leif Neland , FreeBSD Questions Subject: Re: K6-2/333, was: Re: Debug kernel by default (was: System sizewith-g) References: <3709EE06.77F97B9E@uswest.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93.2i In-Reply-To: <3709EE06.77F97B9E@uswest.net>; from Darren Pilgrim on Tue, Apr 06, 1999 at 04:20:38AM -0700 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tuesday, 6 April 1999 at 4:20:38 -0700, Darren Pilgrim wrote: > unknown@riverstyx.net wrote: >> On Mon, 5 Apr 1999, Darren Pilgrim wrote: >>> unknown@riverstyx.net wrote: >>>> I may be out to lunch on this one, but I'm pretty sure that the multiplier >>>> is for the internal clock of the chip. So, if, after applying the >>>> multiplier to one chip you get 300MHz, and after applying a different >>>> multiplier to a different chip with a different bus speed you also get >>>> 300MHz, you get two chips that perform the exact same number of >>>> operations/sec. The difference is the bus speed, which affects I/O >>>> performance, etc. A 100 MHz bus with a x3 multiplier will outperform a 66 >>>> MHz bus with a x4.5 multiplier because the CPU will have to wait more >>>> often when it wants to fetch non-cached data from RAM. >>> >>> While this is mathematically and theoretically sound thinking, tests >>> have shown that there is little CPU/memory performance gain with a >>> 100MHz bus. Just take a look at www.tomshardware.com. As for my own >>> systems, I run K6-2 333s at 5x66 just because it sets the PCI and AGP >>> clocks at their spec'd rate of 33 and 66MHz, respectively, while >>> providing the CPU's spec'd 333MHz. >> >> I've seen good speed gains by moving to a 100MHz bus, although this was >> for servers that were doing a lot of database work and heavy network >> traffic. Perhaps it wouldn't matter much for servers doing more >> calculation-intensive work? > > Aye, in a server setup a faster bus does make a difference, but my > reference (Tom's HW) is for workstations. Did I miss the first part > of the thread, was this discussion about servers? If so, my apologies > for my misunderstanding. No, we're not talking about artificial concepts like servers and workstations, we're talking about the low-level behaviour of the processor and memory. > Disk and memory work in a server can max a slower FSB, but if the > server is being used for CPU-intensive work, then what's the point > of spending extra for a server? I'm not sure I understand this statement. To restate it: the whole matter is relevant only to processor and memory. If your bottleneck is disk I/O, you're not going to see much difference. If you're running lots of long-running instructions such as double floating point divides, the bottleneck is the processor, not the cache interface. If you're running CPU bound with a typical instruction mix (single-cycle execution) and you're accessing a large amount of memory, you will see a significant difference. Depending on what a "server" or "workstation" is doing, any may fit into any of these categories. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message