Chipsets and memory speed...

[Mark Hahn]

> Anyone know the difference in bandwidth/stream performance between a PC with
> a Duron vs an Athlon cpu?  Is there much/any difference?

none: duron and thunderbird differ only in size of onchip cache
(192K vs 384K - those are actual capacities; coppermine's is 256K).

> I looked at the stream benchmark pages, but didn't find any benchmarks using
> the Duron.

here's one:

Function      Rate (MB/s)   RMS time     Min time     Max time
Assignment:   525.1589       0.0305       0.0305       0.0306
Scaling   :   505.7214       0.0317       0.0316       0.0317
Summing   :   553.1737       0.0434       0.0434       0.0435
SAXPYing  :   523.9031       0.0458       0.0458       0.0459

that's for a duron/600, 128M PC133 sdram (cas2, I think - bios doesn't say).

it's interesting to consider the "efficiency" of various cpu/northbridge/dram
combinations.  the above machine delivers 500-550 MB/s out of a theoretical
(never-possible) 1066 MB/s: 47% efficiency.  good old PII/bx/PC100 boxes 
would deliver 3-400 MB/s out of 800 MB/s: around the same efficiency.  
i840 machines seem to max out at around 550 MB/s out of 3200, for a record
of around 17% efficiency!  otoh, rumor has it that i850's deliver more like
1400/3200, back into the 40-50% range, and well into Alpha territory...

of course, stream doesn't credit the machine for write-allocate traffic,
which would "improve" the numbers by 3/2 or 4/3...

regards, mark hahn.