Date: Wed, 02 Oct 96 12:09:47 PST From: BRETT_GLASS@infoworld.com To: "Michael L. VanLoon -- HeadCandy.com" <michaelv@MindBender.serv.net> Cc: rgrimes@gndrsh.aac.dev.com, narvi@haldjas.folklore.ee, obrien@nuxi.cs.ucdavis.edu, freebsd-hardware@freebsd.org Subject: Re: H/W recommendation Message-ID: <9609028442.AA844282062@ccgate.infoworld.com>
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>> But the bargain >> basement version of the Pentium Pro, with the 256 KB cache, will drag in >> the same configuration. Unfortunately, far too many clone vendors just >> HAPPEN not to mention in their ads that they're including the cheaper >> CPU. > Do you have any proof of this? I think you're speculating. I've done benchmarks of heavily-loaded servers with and without the proper chip. Intel originally wanted *all* Pentium Pros to have half a meg of cache on board (see their earliest announcements), and for good reason: it's needed. Otherwise, the ratio of internal to external bus speeds is a killer. > And, I don't know how you can call the 256K P6 the "bargain basement" > when it costs as much as the *highest* speed Pentium. Because it's under-engineered to pinch pennies. Again, Intel originally specified the parts to ALL have 512K of cache. > ... But if you like paying $1200 for your processors, you can think of > them any way you like. :-) Usually, a high price for a chip means either great demand or yield problems. I can't speculate on Intel's rationale, but in this case, both factors could be important. > Besides, as already pointed out above, the 256K Pentium Pro cache is > already *way* faster than any size cache on a Pentium. Plus, with a 256K > cache you're already taking about hits in the 90+% range. On a personal machine, maybe. But not on a UNIX server with a substantial working set. Or on a multiprocessing machine. > 512K would be nice, but its definitely at the far side of diminishing > returns. Not when the penalty for using the external bus is so high. When misses carry a high cost, a higher hit rate is required. --Brett
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