Date: Tue, 22 May 2001 23:44:50 -0500 From: Mike Meyer <mwm@mired.org> To: Kent Stewart <kstewart@urx.com> Cc: questions@freebsd.org Subject: Re: Dual Ppro motherboards Message-ID: <15115.16450.249394.115359@guru.mired.org> In-Reply-To: <6338897@toto.iv>
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Kent Stewart <kstewart@urx.com> types: > I have always thought of MP systems as something that didn't run anything > faster but what they would do is run additional applications equally slowly. Yup, that's what they are. They're really nice if you have lots of applications that are otherwise i/o bound. For typical single-user use, they aren't so great. For Unix power users - who have a tendency to have other things going in the background - an extra processor is also a nice thing to have. Of course, if you're developing applications that run in one of those environments, having a second processor so you can do some testing in the environment is also nice. That's why I bought one. When it's not fast enough to be a workstation anymore, I'll probably go buy a single-CPU system, and keep this one around for a test system. It's going to be interesting to see what causes that to happen. > The compiler's on Cray's were the best the world had to offer in 1990. > However, when you turned on full MP and vector support, a 486-PC would out > compile it on a line for line basis. The PC was fast because it didn't have > to worry about pipelines and producing do-loops that could be run on more > than one processor. Another thing to consider is the architecture of the two machines. Crays was designed for crunching numbers, generally in large arrays. Doing character manipulation was a lot of work - you had to shift the word to the character you wanted then mask it off, so that while you were doing a lot more instructions per second than a conventional machine, you were also doing a lot more instructions for each unit of work. The end result was that unix character-crunching benchmarks on a Cray performed about as well as a fast minicomputer of the time. <mike -- Mike Meyer <mwm@mired.org> 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
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