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From: Mike Houston (mhouston_at_[hidden])
Date: 2005-10-31 11:22:09

Same performance problems with that fix. In fact, if I ever use tcp
currently, OpenMPI crashes...


George Bosilca wrote:

> If there are several networks available between 2 nodes they will get
> selected. That can lead to poor performances in the case when the
> second network is a high latency one (like TCP). If you want to
> insure that only the IB driver is loaded you have to add in the
> .openmpi/mca-params.conf the following line:
> btl_base_exclude=tcp
> This will force the TCP driver to be unloaded (always). In order to
> use this option you have to have all nodes reacheable via IB.
> Thanks,
> george.
> On Oct 31, 2005, at 10:50 AM, Mike Houston wrote:
>> When only sending a few messages, we get reasonably good IB
>> performance,
>> ~500MB/s (MVAPICH is 850MB/s). However, if I crank the number of
>> messages up, we drop to 3MB/s(!!!). This is with the OSU NBCL
>> mpi_bandwidth test. We are running Mellanox IB Gold 1.8 with 3.3.3
>> firmware on PCI-X (Couger) boards. Everything works with MVAPICH, but
>> we really need the thread support in OpenMPI.
>> Ideas? I noticed there are a plethora of runtime options configurable
>> for mvapi. Do I need to tweak these to get performacne up?
>> Thanks!
>> -Mike
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> "Half of what I say is meaningless; but I say it so that the other
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> Kahlil Gibran