Date: Mon, 29 Jun 1998 09:52:05 -0400 (EDT) From: "Christopher G. Petrilli" <petrilli@dworkin.amber.org> To: Atipa <freebsd@atipa.com> Cc: Niall Smart <rotel@indigo.ie>, freebsd-smp@FreeBSD.ORG Subject: Re: PPro vs PII Message-ID: <Pine.BSF.3.96.980629094802.28663A-100000@dworkin.amber.org> In-Reply-To: <Pine.BSF.3.96.980628203701.5661A-100000@altrox.atipa.com>
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On Sun, 28 Jun 1998, Atipa wrote: > The P2 will smoke it. Better yet, go up to 350 or 400MHz, then you can > utilize 100MHz system bus. This is a red herring... the system bus was a big restriction back when the cache was running at bus speed---any increment made a huge difference, but with the current PII architecture, the bus speed has long since ceased to be a problem. How many devices do you know that can saturate a PCI bus constitently? Don't use this as a reasoning. > Since the P2 has DIB (dual independent bus) for the L2 cache, higher clock > rates, and much faster DRAM access, you'll definitely notice the > difference. Pros are at the end of their lifecycle, and will be hard to > support. The PROs will be faster ata given clock speed, and with the cache architecture of the Pros, probably at 50% above that, given a normal model of execution (80-90% cache hit rate). Remember, that you can get PPros with 512K or 1Mb of L2 cache that is running 1:1 with the chip, rather than 2:1. The big problem in most systems in my view (having been responsible for system optimization of mainframes and large UNIX boxes) is never the CPU---unless you're doing scientific applications, then it's usually memory---it's almost always I/O bandwidth. A faster disk, more memory for caching, more SCSI busses, etc, will make a BIG impact on your overal system throughput---which is a much better measure than "boboMIPS" :-) Just cuz you're CPU can spin faster, doesn't mean it doesn't do anything useful during those cycles. Chris -- | Christopher Petrilli | petrilli@amber.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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