2 research outputs found
Parallelizing the XSTAR Photoionization Code
We describe two means by which XSTAR, a code which computes physical
conditions and emission spectra of photoionized gases, has been parallelized.
The first is pvm_xstar, a wrapper which can be used in place of the serial
xstar2xspec script to foster concurrent execution of the XSTAR command line
application on independent sets of parameters. The second is PModel, a plugin
for the Interactive Spectral Interpretation System (ISIS) which allows
arbitrary components of a broad range of astrophysical models to be distributed
across processors during fitting and confidence limits calculations, by
scientists with little training in parallel programming. Plugging the XSTAR
family of analytic models into PModel enables multiple ionization states (e.g.,
of a complex absorber/emitter) to be computed simultaneously, alleviating the
often prohibitive expense of the traditional serial approach. Initial
performance results indicate that these methods substantially enlarge the
problem space to which XSTAR may be applied within practical timeframes.Comment: ADASS 2008 (Quebec) proceedings (4 pages, 1 figure
MPI_XSTAR: MPI-based Parallelization of the XSTAR Photoionization Program
We describe a program for the parallel implementation of multiple runs of
XSTAR, a photoionization code that is used to predict the physical properties
of an ionized gas from its emission and/or absorption lines. The
parallelization program, called MPI_XSTAR, has been developed and implemented
in the C++ language by using the Message Passing Interface (MPI) protocol, a
conventional standard of parallel computing. We have benchmarked parallel
multiprocessing executions of XSTAR, using MPI_XSTAR, against a serial
execution of XSTAR, in terms of the parallelization speedup and the computing
resource efficiency. Our experience indicates that the parallel execution runs
significantly faster than the serial execution, however, the efficiency in
terms of the computing resource usage decreases with increasing the number of
processors used in the parallel computing.Comment: 5 pages, 1 figure, accepted for publication in Publications of the
Astronomical Society of the Pacific (PASP