Top 500 trends

Joachim Worringen joachim at
Wed Nov 27 13:20:22 EST 2002

Mark Hahn:
> out of curiosity, do you mean "PCs have improved a lot",
> or "big iron is even faster now"?
> I tend to think of Stream as being embarassingly parallel,
> thus doable well on a simple grid of chickens ;)

STREAM bandwidth is a performance characteristic: it's the bandwidth that a 
single processor achieves with the STREAM benchmark. It's not an application.

To illustrate: on an SX-6, this is in the range of 25 GB/s/CPU on a 8-CPU 
node. A Pentium-4/Xeon Dual-SMP node get's about 0,5 GB/s/CPU (E7500 chipset 
- which has dual channel RAM, IIRC). This alone gives a performance advantage 
of about a factor 20-40 if not inside the caches, which shows in the MFLOPS 
efficiency (achieved vs. peak) of many codes (the ones which can be 

The SX-5 had even higher memory bandwidth, but in turn, the SX-6 is has become 
more cost- and energy-efficient.


Joachim Worringen - NEC C&C research lab St.Augustin
fon +49-2241-9252.20 - fax .99 -

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