Date: Thu, 2 Feb 2012 00:09:48 +0000 From: Anton Shterenlikht <mexas@bristol.ac.uk> To: freebsd-questions@freebsd.org Subject: OpenMP on FreeBSD Message-ID: <20120202000947.GA71405@mech-cluster241.men.bris.ac.uk>
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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
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