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(removed obsolete tutorial reference, mentioned how to disable OpenMP parallelization, which the QE user docs describe as less mature.) |
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The above example requests two whole nodes for a total of 64 single-threaded processes. This is certainly more processors than is needed for the silicon tutorial case. Please be aware that suitable selection of a process count is complicated, but it is your responsibility to choose an efficient number. | The above example requests two whole nodes for a total of 64 single-threaded processes. This is certainly more processors than is needed for the silicon tutorial case. Please be aware that suitable selection of a process count is complicated, but it is your responsibility to choose an efficient number. | ||
= Segfaults with OpenMPI 3.1.2 = | |||
Users have reported random segfaults on Cedar when using Quantum ESPRESSO versions compiled for OpenMPI 3.1.2 in single-node jobs (shared memory communication). These issues seem not to happen with other versions of OpenMPI. If you experience such problems, first try to use an OpenMPI 2.1.1-based toolchain. For example: | |||
{{Commands | |||
|module load gcc/5.4.0 | |||
|module load openmpi/2.1.1 | |||
|module load quantumespresso/6.3 | |||
}} | |||
= Notes = <!--T:5--> | = Notes = <!--T:5--> |