I have what I thought would be a sequential program in a file
Pi_X10_Sequential.x10 (it a small "Calculate Pi using Quadrature"
program -- I could send it to the list but it is available in the Bazaar
branch at http://www.russel.org.uk/Bazaar/Pi_Quadrature; use
http://www.russel.org.uk:8080/Bazaar/Pi_Quadrature if you just want to
browse rather than branch).
Using the Java backend but compiling with x10c:
|> x10c Pi_X10_Sequential.x10
|> x10 Pi_X10_Sequential
<< . . . all 8 cores at 90%+ for > 70s >>
compilation is successful but on execution on a twin-Xeon workstation
(i.e. 8 cores) all 8 cores go to 90%+ usage permanently seemingly
forever. This is strange behaviour for a sequential program! Is it
though what should be expected at this stage of X01/Java backend
development?
I then tried switching to using the C++ backend on the grounds that it
has been worked on more and the Java backend is far behind. Compilation
is successful but on execution of the compiled code:
|> x10c++ -o Pi_X10_Sequential Pi_X10_Sequential.x10
|> Pi_X10_Sequential
0: xlupc transport: missing environment variable: MP_CHILD
Aborted
|>
This doesn't really qualify as the most helpful message ;-) OK so the
install instructions are very clear that runx10 needs to be used but I
am not sure the "How to compile and run X10 programs" is on the website,
only in the INSTALL.txt file. (But maybe I just missed it.)
When run correctly as:
|> runx10 Pi_X10_Sequential
==== X10 Sequential pi = 3.141592653589971
==== X10 Sequential iteration count = 1000000000
==== X10 Sequential elapse = 22.918572312999999
so clearly things work as they should. Except that the problem left to
me now is that this is about 2.5x slower than C, C++, Java, Scala,
Fortran -- which is a bit of a problem.
(I know this is effectively a microbenchmark, but that is not what the
example is being used for, so please no hate mail on the topic of
micrbenchmarks :-)
--
Russel.
=============================================================================
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Road m: +44 7770 465 077 xmpp: rus...@russel.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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