maximum number of threads for openMP

Hi All,

We got a new server with 72 cores (36 physical CPUs, each hyper threaded). We are still working out some kinks, so we have not yet installed the PGI compilers. I took some code compiled on an otherwise identical machine with 40 threads (20 CPUs, each hyper threaded). I can run the code on the new machine, but I can only go up to 64 threads. Is this a hardware or a software limit? If it is the latter, how can I use 72 threads on the new machine?


Hi Jerry,

Use the environment variable “OMP_THREAD_LIMIT” to set the maximum number of OpenMP threads. It defaults to 64 and has a maximum of 256.

Hope this helps,

Hi Mat,

Thanks, that did the trick.