From: Charlie Zender <zender@uc...> - 2008-12-07 20:49:27
At least two independent users of NCO 3.9.5 on AIX
machines have found threading problems with ncea/ncra
that lead to wrong answers. We have been unable to
reproduce the problem on other architectures and are
investigating the causes and full-extent of the problem.
This has proven to be a difficult problem to isolate,
and unfortunately, it can produce answers which are not
obviously wrong, but are only subtly wrong.
So, in the meantime, the following confirmed workarounds are available:
1. On multi-core CPUs, run 3.9.5 arithmetic operators explicitly with
one thread by adding the "-t 1" switch
2. Downgrade to NCO 3.9.2
3. Recompile the 3.9.5 operators with OpenMP turned off.
Do this with CPPFLAGS='-U_OPENMP'
We will fix the problem one way (precisely), or
another (turning off threading until we find the problem)
in NCO 3.9.6, expected to be release between 12/26 and 1/1.
Charlie Zender, Department of Earth System Science
University of California, Irvine (949) 824-2987 :)
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