Tim Prince wrote:
>In my experience,
>'mpirun -np 2' on a single CPU P4 increases throughput by about 10% from -np
>1, but that gain doesn't hold up for scaling to a large cluster with simple
>interconnects.
>
Tim,
My experience agrees with yours. When I ran the NASA Parallel
Benchmarks on a Xeon cluster with even plain Fast Ethernet, it
was always faster to turn off HT (we did it at the kernel level and
at the BIOS level) These results are also supported by the following:
http://computational-battery.org/Maskinvare/Hyperthreading.html
(which did it for OpenMP codes). I can't seem to find it the link
right now, but I remember one from someone at Scali who saw
the same thing.
Jeff
|