Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: [OMPI users] TCP Latency
From: Andy Georgi (Andy.Georgi_at_[hidden])
Date: 2008-07-28 14:53:58


Hi all,

we use Chelsio S320E-CXA adapters
(http://www.chelsio.com/assetlibrary/products/S320E%20Product%20Brief%20080424.pdf) in one of our
clusters. After tuning the kernel i measured the ping pong latency via NetPIPE and got ~12us which
is pretty good for TCP i think. So i wrote a simple ping-pong-kernel and was really terrified about
the ~45us i got with OpenMPI 1.2.6. Are there any hints how we can reduce the MPI latency? To
increase the bandwidth we already set the buffer sizes but we couldn't find a parameter which can be
relevant for the latency. Every hint is welcome.

Thanks and best regards

Andy

-- 
Dresden University of Technology
Center for Information Services
and High Performance Computing (ZIH)
D-01062 Dresden
Germany
e-mail: Andy.Georgi_at_[hidden]
WWW:    http://www.tu-dresden.de/zih