•  Winterhawk Performance
•  PCM (version 2) Coupler Performance on Winterhawk 1 (Tony Craig)
•  PCM (version 2) Coupler Improvements (Chris Ding and Yun He)
•  Winterhawk I/O
•  Performance on Other Machines

Winterhawk 1 and Winterhawk 2 Performance

Below are tables containing the performance of the Parallel Climate Model (version 1) on the IBM SP Winterhawk 1 and Winterhawk 2 nodes.  Units are wallclock seconds per simulated day.

The performance characteristics of PCM on the IBM SP are well known.  Namely:

• scaling to 64pes is marginally acceptable
• ccm inherently does not scale linearly beyond 32pes due to internal 1-D data decomposition of T42 spectral problem size
• coupler does not scale well due to mapping and conservation (global sum) bottlenecks, but is less than 20% of the total computation time
• pop barotropic solver scales poorly
• ice scales relatively well

Specific performance for the PCM (version 2) coupler was produced by Tony Craig.   Craig's coupler PCM coupler performance summary .

Chris Ding and Yun He (NERSC) have further analyzed the PCM (version 2) coupler performance, and have produced improvements.  Improvement summary .
 
 

Winterhawk 1 I/O

The relative importance of I/O (on gseaborg at NERSC, the IBM SP WH1 machine) is shown in the following plot.  During the integration, history and restart files are written at the end of every month for each component.

• red:      full model time per simulated day
• green:  ccm time per simulated day
• black:  pop time per simulated day
• blue:    ice time per simulated day.

For comparison with other machines, see results presented in November 1999 at SC99 in Portland, Oregon:

•  PCM Performance Full Model
•  PCM Performance CCM plus coupler
•  PCM Performance POP Ocean
•  PCM Performance POP Ocean - Barotropic Solver
•  PCM Performance Ice