Runtime/Scaling behaviour on GPU platforms

The wall clock time of jobs is influenced by following factors:

1. Scaling with respect to each GPU: the number of threads (SMP) and/or processes (MPI,hybrid) determines the load on each GPU card
2. Scaling with the number of GPU: Only if the job is big enough and exploits the full power of at least one GPU card
3. Binding of threads/processes to specific CPU cores slows down and wastes CPU cycles

Memory considerations

• SMP runs of NAMD only use about 600 MB of resident memory