[Beowulf] WRF model on linux cluster: Mpi problem

Joachim Worringen joachim at ccrl-nece.de
Wed Jul 6 01:05:52 PDT 2005

Federico Ceccarelli wrote:
> Hi, 
> I did the Pallas benchmark...after removing openmosix...here are the
> ping-pong and ping-ping results...for 2 processes
> What do you think about them?
> Why the bandwidth is raising and decreasing many times as the #bytes
> grow?

The latency is quite high and grows too fast from 0 to 8 bytes. But most of all, 
the bandwidth should be constant with at least 80MB/s, better >100MB/s for large 
messages. Something is wrong, probably with your ethernet setup. I remember such 
effects for half/full-duplex mismatch with 100Mb auto negotiation problems 
between NIC and switch.


Joachim Worringen - NEC C&C research lab St.Augustin
fon +49-2241-9252.20 - fax .99 - http://www.ccrl-nece.de

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