The Grid-Computing library PACX-MPI
Extending MPI for Computational Grids
The library PACX-MPI (PArallel Computer eXtension)
enables scientists and engineers
to seamlessly run MPI-conforming parallel application on a Computational Grid,
such as a cluster of High-Performance Computers like MPPs,
connected through high-speed networks or even the Internet.
The parallel application doesn't have to be changed in any way but only
recompiled and linked against PACX-MPI.
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| Communication between MPI processes internal to an MPP is done with
the vendor MPI, while communication to other members of the Metacomputer is done via the
connecting network. The characteristics of such systems show two different levels
of quality of communication: |
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Usage of the optimized vendor-MPI library: Internal operations are
handled using the vendor-MPI environment on each system. This allows
to fully exploit the capacity of the underlying communication
subsystem in a portable manner.
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Usage of communication daemons: on each system in the metacomputer two
daemons take care of communication between systems. This allows to
bundle communication and to avoid to have thousands of open
connections between processes. In addition it allows to handle
security issues centrally. The daemon nodes are implemented as
additional, local MPI processes. Therefore, no additional
TCP-communication between the application nodes and the daemons is
necessary, which would needlessly increase the communication latency.
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Initially PACX-MPI was developed to connect a
Cray-YMP vector computer to an Intel Paragon with only a subset of MPI calls.
It has been extended to support up to 1024 computers to form a Metacomputer,
support the full MPI-1.2 and parts of MPI-2.0 standard and
make best usage of resources and optimize communication.
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