Re: CPU Speed vs. Memory Bandwidth

From: Hugh LaMaster -- RCS (
Date: Fri Apr 23 1993 - 10:51:04 CDT

>Except that one of the tests is simply a copy, which should not
>require any FPU intervention.

I guess I bungled my attempt to express what you just wrote.
Sorry about that. "Compute" was a poor choice of words intended
to express that we are looking at CPU load/store here, plus maybe
FP operations, but not the raw speed of the bus. John Mashey's
post is typical of what you get from a vendor -- the guaranteed
not to exceed speed of the bus. However, in the case of the SGI,
only a small fraction is available to an application in any single CPU.
I admit that I am disappointed by the SGI numbers. There seems to
be a bit of a cache bottleneck there. The DEC 3000/500 looks better:
and, I am told, has better random access speed than IBM.

I hope you don't mind my posting your results. I couldn't resist
the opportunity to bring up my favorite subject while responding
to someone else.

>>Does anyone have numbers for the new DEC AXP systems, and new HP
>>7100-based systems? Can someone from DEC or HP post results?
>I have received a number of new results lately -- check the archive.
>These include SGI Challenge, SGI Crimson, DEC 3000/500, HP 9000/755,
>and IBM RS/6000-580. The results are very interesting....

I had fetched the previous week's table, which had only the SGI and IBM.
I just fetched the latest and posted the HP and DEC numbers as a
supplement (I hope before 20 other people do as well.) Thanks!

Hugh LaMaster

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