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Subject: Re: [OMPI users] TCP Bandwidth
From: Steve Wise (swise_at_[hidden])
Date: 2008-08-18 15:36:07


Andy Georgi wrote:
> Steve Wise wrote:
>> Are you using Chelsio's TOE drivers? Or just a driver from the distro?
>
> We use the Chelsio TOE drivers.
>
>
> Steve Wise wrote:
>> Ok. Did you run their perftune.sh script?
>
> Yes, if not we wouldn't get the 1.15 GB/s on the TCP level. We had
> ~800 MB/s before
> primarily because of too small TCP buffers.
>
> The difference of more than 200 MB/s between 1.15 GB/s we get with
> iperf and the 930 MB/s we
> measured with a MPI-Ping-Pong test is too large, i think. Something in
> Open MPI seems to slow it down.
>
Sounds like the TOE setup is tweaked to get decent sockets performance.

So OMPI experts, what is the overhead you see on other TCP links for
OMPI BW tests vs native sockets TCP BW tests?