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Performance of NEMO V3.0

The scaling on NEMO V3.0 is similar to that of version 2.3. For 398 and 794 processor runs the total runtime was found to be highly unstable, varying as much as 400%. Due to these variations, the results shown by figure 9 have been taken from the best of 5 runs.

Figure 9: Performance of NEMO V3.0 showing the breakdown of the total runtime for various processor counts. All tests carried out using PGI compiler
Image totalruntime_v3.0

The variability of the total runtime appears to be highly dependent on the system load. This makes predicting the length of a run or indeed attempting to specify an appropriate wallclock time difficult. Anything that can be done to improve this situation will be hugely beneficial to the researchers.