[Beowulf] Threaded code

Mark Hahn hahn at physics.mcmaster.ca
Tue Aug 17 11:34:41 EDT 2004


> variables? (do you have an NCPU=1 or something like that hanging around?)

afaikt, when threads are enabled, atlas compiles in the number of threads,
based on what it detects on the machine doing the compilation.  so, for
instance, if you happened to compile atlas on this machine with the uni
kernel, (or some other uni) you'd get no threads.  this is a bit
counterintuitive to anyone used to OMP_NUM_THREADS, but it certainly
makes sense for atlas.

> Are you sure you are using only one CPU (e.g. what tests are you using 
> that indicate a single CPU)?

yes, another good question.  if you simply don't get any speedup from using
threads, it doesn't necessarily imply that you're not using threads ;)

regards, mark hahn.

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