Parameterisation to tailor commodity clusters to applications

Parallel applications can be parameterised by the quotient gamma /sub a/ of flop/s and data transfers between the processors, and by the machine-dependent, maximum local processor performance r/sub a/. Clusters can be parameterised by the quotient gamma /sub m/ of r/sub a/ and the per processor network communication bandwidth b/sub m/. All those parameters are predictable. In parallel machines, the communication time is smaller than the computing time if gamma /sub m/[left angle bracket] gamma /sub a/. A first principles chemistry application is described and parameterised. Benchmarks on the Swiss-T1 cluster machine show that the predicted inter-processor communication and computing times correspond well to the measured times. These parameterisations can now be used to tailor clusters from commodity components to the applications. (16 References).