[Beowulf] Home beowulf - NIC latencies
josip at lanl.gov
Tue Feb 8 08:54:07 PST 2005
Rossen Dimitrov wrote:
> So, if you really want to optimize the use of your cluster resources, in
> addition to the network and compute nodes, you will need to also
> consider the communication middleware and the design of your application
> and how they all work together.
Are there any projects that would expand the ability of MPI application
programmers to provide performance hints to the MPI library? For
example, hints indicating that certain messages are latency sensitive
whereas others need optimal bandwidth and low CPU overhead?
One can already obtain some MPI performance data through the PMPI
mechanism, and Rossen is helping develop MPI PERUSE
(http://www.mpi-peruse.org/) intended to provide even more detail. I'm
asking about the other direction of information flow, i.e. performance
hints from the application to the MPI layer...
Ideally, such hints would be propagated fairly close to the actual
hardware, e.g. application hints would guide the MPI library in
selecting improved interrupt mitigation strategies used by the network
interfaces (assuming that a suitable API exists for the underlaying
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