OpenMP on FreeBSD

[Anton Shterenlikht]

I'm new to OpenMP. I wonder
if there are any special considerations
when running OpenMP on FreeBSD?

For example, I have this OMP parallelised
fortran program, nested do loops, compiled
with gfortran46. When I run it with 2 threads
on a 2-cpu box, I see in top(1):

  PID    UID   PRI NICE   SIZE    RES STATE   C   TIME    CPU COMMAND
63995   1001    89    0 57048K 34272K CPU1    1   1:06 55.08% dummy.sx{dummy.sx}
63995   1001    87    0 57048K 34272K RUN     1   1:02 52.39% dummy.sx{dummy.sx}
   11      0   155 ki31     0K    32K RUN     0 376:58 51.46% idle{idle: cpu0}
   11      0   155 ki31     0K    32K RUN     1 368:18 45.36% idle{idle: cpu1}

I wonder why, even after a minute of run time,
I still have nearly a whole cpu idle?

As a result the run time with 2 threads
is nearly identical to run time with 1 thread. 

It's likely that I'm not using OMP correctly,
but I wanted to check if there are any
special FreeBSD related issues to bear
in mind when coding with OMP.

Thanks

-- 
Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
Tel: +44 (0)117 331 5944
Fax: +44 (0)117 929 4423