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From: dawg6844@uxa.cso.uiuc.edu (<blank>)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.system
Subject: Re: How many MIPS is the Mac?
Message-ID: <1991Feb16.195110.6278@ux1.cso.uiuc.edu>
Date: 16 Feb 91 19:51:10 GMT
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mkelly@cs.uoregon.edu (Michael A. Kelly) writes:


>How many MIPS is the Mac capable of?  I see ads for workstations such as the
>SPARCs which say they run at 12 or 26 MIPS, and I think 'but how does that
>compare to my Mac IIcx?'

>Thanks in advance,

>Mike.
>--
>_______________________________________________________________________________
>Michael A. Kelly                                     America Online: Michael792
>mkelly@cs.uoregon.edu                                    Compu$erve: 73567,1651
>_______________________________________________________________________________

Patterson & Resnick, the founders of RISC, spend a chapter of their
latest book on hardware design explaining why MIPS and MFLOPS, the two most
common 'measures' of computer performance are basically hogwash.  Since Cycles
per Instruction (CPI) and the design of the FPU (if it is there) are different
from machine to machine, it is meaningless to compare machines of different
architectures by using Mips or Mflops.  (Similar to comparing cars by how many
times the pistons go up and down).

They argue that the only true measure of computer performance is the execution
time of REAL programs (not 'toy' programs or benchmarks).

example:
a machine with optional floating point hardware.
it generally takes more clock cycles per flop then per integer instruction,
so programs that use the optional FPU take less time but have a LOWER MIPS than
programs that use software flop emulation, which executes many more instructions(making it slower) but has higher MIPS because the instructions it executes are
smaller.  ie: MIPS can vary INVERSELY to performance in certain situations.

So how does all this answer your question?  It doesn't.
The only true way to compare these two machines is to run the same software and
compare execution times.  (compile the same large program perhaps?  but even that is bad, because are the compilers the same?)

I am a smalltalk programmer, and smalltalk has the unique feature of being able
to run across many platforms.  A large package we developed here runs about 
one and a half to two times as fast on the Sparc I in the lab as it does on my
IIci.  That ought to give you some idea about relative performance.
(Although even this isnt perfect, as the VM interface is different for the two
machines)

So anyway, have a nice day :)
Dan