Performance

Cocoa is designed for high performance on modern GPU and CPU architectures. This page presents benchmark results comparing Cocoa with ADCIRC on a representative large-scale simulation, including strong-scaling behavior in CPU-MPI mode and single-GPU performance across three GPU generations.

Benchmark Configuration

The benchmark is a Hurricane Katrina (2005) hindcast with the following characteristics:

• Mesh size: 1,568,749 nodes

• Forcing: Tidal boundary, tidal potential, and hurricane wind and pressure fields

• Time step: 2 s for both the implicit and explicit (lumped-mass) solvers, for both models

• Simulated duration: 25 days

ADCIRC runs use double precision throughout. Cocoa computes in double precision with single-precision storage for bandwidth-bound fields.

Hardware:

• CPU (PSC Bridges-2): dual-socket AMD EPYC 7742 64-core nodes (128 cores per node), 128 to 1024 MPI ranks (1 to 8 nodes)

• GPU (Lambda Labs): NVIDIA H100 (SXM5, host Intel Platinum 8480+) and NVIDIA B200 (SXM6, host Intel Platinum 8592+), single device

• GPU (workstation): NVIDIA V100 (host AMD Ryzen 9 9950X), single device

Both solvers use the same time step (2 s) and run for the same simulated duration, so the implicit and explicit results are a direct, step-for-step comparison. Results are still presented separately per solver because they exercise different work per step.

Implicit Solver Results

Fig. 9 Wall-clock time for the implicit solver (dt=2s) on the 1.57M-node Hurricane Katrina hindcast.

Model	Hardware	Wall Time
ADCIRC	128 cores (1 node)	607m (10.1h)
Cocoa	128 cores (1 node)	492m (8.2h)
ADCIRC	1024 cores (8 nodes)	124m (2.1h)
Cocoa	1024 cores (8 nodes)	142m (2.4h)
Cocoa	1x V100 GPU	207m (3.5h)
Cocoa	1x H100 GPU	82m (1.4h)
Cocoa	1x B200 GPU	62m (1.0h)

Explicit Solver Results

Fig. 10 Wall-clock time for the explicit lumped-mass solver (dt=2s) on the 1.57M-node Hurricane Katrina hindcast.

Model	Hardware	Wall Time
ADCIRC	128 cores (1 node)	450m (7.5h)
Cocoa	128 cores (1 node)	317m (5.3h)
ADCIRC	1024 cores (8 nodes)	99m (1.6h)
Cocoa	1024 cores (8 nodes)	78m (1.3h)
Cocoa	1x V100 GPU	72m (1.2h)
Cocoa	1x H100 GPU	35m (0.6h)
Cocoa	1x B200 GPU	34m (0.6h)

CPU-MPI Scaling

Fig. 11 Top: log-log scaling of wall-clock time vs MPI ranks on PSC Bridges-2, one panel per solver, with horizontal reference lines marking Cocoa’s single-GPU wall times for the same solver. Bottom: parallel efficiency relative to each configuration’s own 128-core run.

Wall-clock time in minutes by MPI rank count:

Ranks	Cocoa Implicit	ADCIRC Implicit	Cocoa Explicit	ADCIRC Explicit
128	492	607	317	450
256	266	319	148	239
512	171	160	94	142
1024	142	124	78	99