🚀 go-pugleaf

In article <1989Nov21.015953.13817@elroy.jpl.nasa.gov> david@elroy.jpl.nasa.gov (David Robinson) writes:
>Can anyone with any detailed knowledge compare the new MIPS R6000 with
>the BIT 80Mhz SPARC (B5000)?  BIT is claiming 65 MIPS while the R6000
>is rated at 55 MIPS.  I thought both the R6000 and B5000 were manufactured
>by BIT and probably with the same ECL process.

Right now, this is probably premature in most possible ways.

1) It is no secret that both are manufactured by BIT with the same
ECL process.

2) The BIT claims are for a chipset, whereas MIPS is claiming a system that
yields 55-(MIPS)-mips.  Sun has not yet published the detials of the
SYSTEM(s) that they're building.
Note that chipsets and systems are different [in my car model,
one is measuring RPM at the engine, and the other speed on the road].
This doesn't say one is better or worse than the other, just that they're
different.  BIT isn't building systems, and their claims imply few committments
about what Sun is doing with the chips.

3) As always, especially on these fast machines, relative performance
ratings will vary around quite a bit, i.e., the faster things get,
the worse an approximation a single-number-mips-rating is.

4) Remember that different vendors (legitimately) have different ideas of -mips
ratings, and you believe they're equivalent at your peril; this has been
true forever in the computer business, starting (most notably) with
the difference between IBM-mainframe-mips and VAX-mips ratings.

Vendors can call their -mips whatever they want, but they're
essentially meaningless except when you have comparable & realistic
benchmarks.  REMEMBER A VENDOR CAN LABEL THEIR MACHINES WITH ANY
MIPS-RATING THEY LIKE, AND MAYBE THEY'LL BE CONSISTENT WITHIN THEIR
PRODUCT LINE (or not), BUT THE PROBLEM COMES WHEN YOU MAKE EVEN THE SLIGHTEST
ASSUMPTION THAT YOU CAN COMPARE THEM.  This is like claiming that
one car has better gas mileage than another because its figures are given
in km/gallon instead of miles/gallon.  A useful thing to have is conversion
factors, if such exist, between different vendor's -mips ratings.
(I say, "if such exist", carefully:
	a) It might be that one number gives a +/-10^% estimate.
	b) It might be that one for integer and one for floating-point
		is needed.
	c) It might that a whole bunch more are needed, especially as
		one gets faster machines.)
For example, one observes that on the SPEC benchmark set,
although the relative performance bounced around, the (16-SPARC-mips)
SPARCsystem 330 and (13-MIPS-mips) MIPS M/120 are quite similar in
overall performance. (It really helps to see the charts superimposed,
which unfortunately do not post very well on the net :-)

Needless to say, cost/mips comparisons are mostly meaningless to compare
vendors with, if you can't calibrate the kinds of -mips used.

Right now, there is insufficient public data to decide
which of the two ECL SYSTEMS is faster, or for which benchmarks,
even for the simplest single-user cases, much less more complex environments.
-- 
-john mashey	DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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