🚀 go-pugleaf

In article <22303@gryphon.COM> scarter@gryphon.COM (Scott Carter) writes:
| The 960 CA can issue three instructions per
| cycle to the chosen three of four execute units.  I believe Intel has figures
| showing that on the average they could infact issue two instructions per clock
| _average_ [over what program set?], hence the 960CA can legitimately be called
| 66 Native MIPS average with 99 Native MIPS peak.

The i960CA decoder can dispatch up to 3 instructions per cycle.
However, the decoder looks at 4 instructions at a time, and it appears
that the decoder cannot be loaded with the next set of 4 instructions
until the current set of instructions have all been dispatched.
Therefore, the "99 Native MIPS peak" can only be attained for one
clock cycle; the left-over instruction in the decoder would be
dispatched by itself in the next clock cycle.  In reality, it is "66
Native MIPS peak".

| How this will work out in
| "reality" who knows?  I'm looking forward to Specmarks for a 960CA Real
| System!

Since the 960CA is targeted for embedded control applications, and has
no MMU nor floating-point, I don't think you will ever see Specmarks
for it.  However, Intel released performance numbers for it at the
i960CA announcement.  The numbers were for a 33 MHz i960CA running
with 64KB of 15ns SRAM and 1MB of 4-cycle inital access, 3-cycle
subsequent access DRAM.  The SRAM was used for instruction memory and
the DRAM was used for data memory.  The benchmarks run were Dhrystone
1.1, Buffer Copy, "Travelling Salesman" solution by simulated
annealing, Pi (compute pi to 500 places), quicksort, bubblesort,
integer matrix multiply, CCITT image compression, and Bezier curve
calculation.

Intel compared its i960CA board running this benchmark suite with a
68030 (20MHz), an i960KA(20MHz), and an Am29000(16MHz) board.
However, the board they used to benchmark the Am29000 was not designed
for performance; rather, it was designed to test the functionality of
ADAPT (Advanced Development and Prototyping Tool) hardware debuggers.
To provide a more fair comparison, I requested the benchmark sources
from Intel, to run on a 30MHz Am29000 board (manufactured by YARC
Systems).  This board uses 2-way interleaved, 100ns DRAM memory for
instructions and 35ns SRAM for data.

I received sources for the non-proprietary benchmarks, compiled them
with the current version of the MetaWare HighC29k compiler, and ran
them on the YARC card.  Here are the final results:


     Absolute Performance

      benchmark     68030     960KA    Am29000    960CA
                    20MHz     20MHz     30MHz     33MHz
quicksort (ms)        286       135        51        50
bubblesort (ms)       291       180        65        85
pi-500 (ms)          6999      3510      1398      1624
anneal (ms)         37210     20910      8119      8388
matmult (us)       186552     74873     49135     26898
dhrystone 1.1        5484     14196     44876     41600


     Performance Relative to 68030 Board

      benchmark     68030     960KA    Am29000    960CA
                    20MHz     20MHz     30MHz     33MHz
quicksort            1.00      2.12      5.61      5.72
bubblesort           1.00      1.62      4.48      3.42
pi-500               1.00      1.99      5.01      4.31
anneal               1.00      1.78      4.58      4.44
matmult              1.00      2.49      3.80      6.94
dhrystone 1.1        1.00      2.59      8.18      7.59
-------------------------------------------------------
      geom mean      1.00      2.07      5.11      5.20



     Performance Normalized to 20MHz, Relative to 68030 Board

      benchmark     68030     960KA    Am29000    960CA
quicksort            1.00      2.12      3.74      3.47
bubblesort           1.00      1.62      2.98      2.07
pi-500               1.00      1.99      3.34      2.61
anneal               1.00      1.78      3.06      2.69
matmult              1.00      2.49      2.53      4.20
dhrystone 1.1        1.00      2.59      5.46      4.60
-------------------------------------------------------
      geom mean      1.00      2.07      3.41      3.15


Thus, it would appear that the "66 Native MIPS", 33MHz i960CA
is about the same performance as the 20 Native MIPS (18
VAX-equivalent MIPS), 30MHz Am29000.




	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)