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This is to notify the community that PBS supports hyper threading on Cray X* series systems using ALPS. No code changes to PBS are required. To use hyper threading, only the aprun call in the job script needs to changerequest hyper threads.
On a Cray X* series system using ALPS PBS creates the values for the vnode's resources based on what is returned in the ALPS inventory response.
PBS sets the resources_available.ncpus value based on the number of compute unit elements returned in the XML inventory response. Refer to the following Cray documentation for an explanation about compute units and CPUs: https://pubs.cray.com/content/S-2529/17.05/xctm-series-programming-environment-user-guide-1705-s-2529/compute-units-and-cpus
This allows PBS to make ALPS reservations for compute units of a node and get all of the hyper threads associated with those compute units.
On an a Cray X* series system with ALPS using Cray's aprun command a user can request to use the hyper threads. Please refer to Cray's man page for aprun.
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