Path: utzoo!attcan!uunet!cs.utexas.edu!usc!apple!bionet!arisia!butcher
From: butcher@arisia.Xerox.COM (Lawrence Butcher)
Newsgroups: comp.arch
Subject: How fast is fast?
Keywords: SPEC
Message-ID: <12035@arisia.Xerox.COM>
Date: 29 Aug 90 07:26:15 GMT
Organization: Xerox PARC
Lines: 22

While eating chinese in downtown asymptotia, we came up with this question:

What is the biggest SPEC mark a computer can have?

To try to make this more concrete, imagine a computer which fetches or stores
one data item each clock.  Let each data reference be to an aligned data item
of the proper size; so that for instance fetching 4 bytes one at a time takes
4 clocks.  (Fetching a 64 bit quantity would take 2 clocks over a 32 bit bus.)
Let it have about 32 integer and 32 floating point registers to allow reuse of
data.  Assume that it never misses a clock due to data dependencies.  It just
does the data references the SPEC programs need, one reference per clock.

At 10 MHz and with a 32 bit bus, what would the SPEC rating be?

At 10 MHz and with a 64 bit bus, what would the SPEC rating be?

What if it had 2 data busses?  Specifically if it could reference 32 bits of
data from the stack AND main memory per clock, what SPEC rating would it have?

What about the same 2 data busses, but with each data path 64 bits wide?

				Lawrence