From: clc5q@hemlock.cs.Virginia.EDU (Clark L. Coleman)
Subject: Re: 100 Mips Intel NeXT (processor comparison)
Organization: University of Virginia Computer Science Department
Date: Tue, 5 Jan 1993 22:05:45 GMT

In article <1992Dec24.190008.25875@ohsu.edu> filibert@ohsu.edu writes:
>In article <1992Dec23.192238.18955@kong.gsfc.nasa.gov>  
>vesper@kong.gsfc.nasa.gov (Greg Vesper - RMS) writes:
>> > 
>> > A little commentary....
>> > 
>> 
>> Your commentary is out of date.  Look at the NEW new HP's. ie the 735 and  
>755.  
>> They beat the alpha's, and at only 99 MHZ - alpha is good, but PA RISC is  
>> better..
>
>So, what you are saying is that HP achieved a performance
>boost from 132 MIPS to 400 MIPS?  This sounds pretty
>far-fetched...  The article states that the Alpha team
>wants to achieve a superiority in clock speed by at least
>50% when Alpha is introduced.  They figured the industry
>leader in 1992 would be at a clock rate of 120 MHz making a
>minimum clock rate for Alpha to be 180 MHz.  It sounds like
>their projections were pretty close, and since they have
>already shown a 150 MHz alpha that achieved a 50% increase
>in performance over the PA-4 at 66 MHz, I think the actual
>release version of Alpha will maintain this advantage. 
>I'm really not up-to-date on the HP line of processors,
>but unless the latest (as compared to July 1992) has
>significant revisions, I find it hard to believe that
>they currently "beat" the latest Alpha technology. 

1) MIPS are marketing hype.  "400 MIPS" is a worthless number to
use when evaluating the Alpha.

2) By reasonable benchmarks (SPECint92 and SPECfp92), the 99 MHz PA-7100
is slightly faster than the 150 MHz Alpha workstations that were just
announced.

3) I want performance on real codes, not MHz. See #2 above.

4) Don't believe the breathless hype from DEC. They are desperate to
   sell everyone on the Alpha in order to recover from their recent
   woes.  Comparing it to previous generations of competitors' machines
   is par for the course.

The 99 MHz HP systems have large primary caches (256KB each, instruction
and data.)  This is implemented on external SRAM (just about the fastest
available.) No secondary cache is used.  The Alpha has small on-chip caches
(8KB each) and then accesses secondary cache over an off-chip bus that is
slower than the CPU clock (e.g. 75 MHz for the 150 MHz systems, I believe.)
The HP will therefore run at 0 wait states much more often that the Alpha
machines of today.

Comparing such dissimilar CPU/cache designs strictly by the internal clock
speed is pointless.  And, as with the MIPS R4x00 family, there are two
clock speeds that you would have to talk about; likewise with the clock
doubling chips from Intel.

The 182 MHz Alpha systems are faster than the 99 MHz HP systems, and the
upcoming 200 MHz systems will be another 10% faster.  But HP is working on
new systems, as well. I predict that there will not be a time in 1993 in
which Alpha workstations are as much as 50% faster than HP at the high end,
yet DEC marketeers continue to befuddle people with that number.

By the way, the 150 MHz Alpha workstations were announced on the same day
in November as their 99 MHz betters from HP.  This was after a year of
vaporous marketing from DEC that claimed they had a chip that was twice as
fast as any chip from the competition (e.g. talking about 200 MHz Alpha chips
in the labs in January of 1992 and comparing them to actual systems that had
been shipping in the 1000s for many months.)  This kind of hyperbole is
associated with desperation in my mind.
-- 
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"It is seldom that any liberty is lost all at once." David Hume
|||  clc5q@virginia.edu (Clark L. Coleman)
Newsgroups: comp.sys.next.advocacy