From: tw5232@albnyvms.bitnet (Teddy Wang)
Subject: Re: MIPS results: Which one is true ???
Reply-To: tw5232@albnyvms.bitnet
Organization: University of NY at Albany
Date: Wed, 22 Jul 92 15:36:37 GMT

In article <33228@cbmvax.commodore.com>, mks@cbmvax.commodore.com (Michael Sinz) writes:
[Useless Stuff Deleted]
>This is really very uninteresting.  For example, the on the 68040,
>the NOP instruction is actually sometimes rather slow.  (Very slow)
>yet the time to execute it is basically 0, but the fact that it forces
>pipeline sync and pending writes to finish means that it can take many
>cycles.  On a 68000, a DIVU or DIVS takes up to 168 cycles.  At 7MHz
>this comes out to 41,700 DIVS per second (0.041 MIPS) but then a
>MOVE register to register takes 4 cycles (1.75 MIPS) but then doing
>just one or the other is not what sofeware does.  Plus, given that
>sometimes you get wait states to memory but you may have a cache on
>the CPU but it may be off for certain memory areas, etc, all make MIPS
>figures for processors useless.  Plus, when you look at the difference
>between the instuctions and what they did, if it takes 5 instructions
>to do something on one processor but it take 10 instructions on the other,
>who cares if the second processor has 50% more "MIPS" since you need
>twice as many MIPS just to make up for the fact that it take more
>instructions to get the job done.
>
>Lets just say that the 68040 is *very* fast.  The 68030 is fast (as is the
>68020 at the same clock rate unless you add the external MMU) and the 68000
>is rather slow (when put beside these others).

More importantly, I think, is the performance of these chips in the REAL WORLD. 
How many people run speed-test and comparison programs day in - day out*.  Put
it plainly, doing a DPaint IV move animation, an 030 equipped 2500 was 6 times
quicker than a standard 2000.  An 040 equipped 2000 was 17 times faster than
the standard 2000.  

Doing screen magnification (from 400% to 800%) on a heavily bitmap-imported
PageStream screen took 2 minutes 35 seconds on a standard 68000 based A2000.
On the 030, the same process took 25 seconds.  The 040 took slightly less than
1 second to do the same.

A Turbo Silver ray-tracing which took 14 hours on the standard A2000, took 30
minutes on the 030 equipped 2500 using the floating point version of the
program.  Since the floating point version of Turbo Silver crashed on the 040,
I used the standard non-floating which took 45 minutes.

You must also realize that many programs are not compiled to optimize the
modern chips (come on Lattice and Manx, get your act together and release a
compiler which is 040 specific.) 

* Actually, the first couple of days I had my Fusion Forty, I ran every
speed-testing program available.  I was real curious at how much performance,
$995 got me.
 
     ////////  
       //                                             twang@thor.albany.edu
      //                                              TWANG@ALBNYVMS.BITNET
     //  eddy Wang                                    TW5232@ALBNYVMS.BITNET
    //   Computer Art and Animation at SUNY Albany
         New Illusions      Albany, NY                  "Increase the Peace..."
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