GPU weak scaling

The plot shows weak scaling of the ABL application with the Smagorinsky LES model using A100 GPUs on the Perlmutter system at NERSC. The domain size is amr.n_cell = 128 128 512 for a single GPU; this is progressively scaled up to 2048 1024 512 for 128 GPUs. This test uses all 4 GPUs per node with GPU-aware MPI communication and runs 100 time steps.

The times shown includes both initialization and time evolution. All I/O and diagnostic calculations are turned off.