On 25-05-2024 03:49, Hongyi Zhao via slurm-users wrote:
Ultimately, I found that the cause of the problem was that hyper-threading was enabled by default in the BIOS. If I disable hyper-threading, I observed that the computational efficiency is consistent between using slurm and using mpirun directly. Therefore, it appears that hyper-threading should not be enabled in the BIOS when using slurm.
Whether or not to enable Hyper-Threading (HT) on your compute nodes depends entirely on the properties of applications that you wish to run on the nodes. Some applications are faster without HT, others are faster with HT. When HT is enabled, the "virtual CPU cores" obviously will have only half the memory available per core.
The VASP code is highly CPU- and memory intensive, and HT should probably be disabled for optimal performance with VASP.
Slurm doesn't affect the performance of your codes with or without HT. Slurm just schedules tasks to run on the available cores.
/Ole