1. A method of determining a system configuration for performing a collective operation on a parallel computer, the parallel computer comprising a plurality of compute nodes, the compute nodes coupled for data communications over a data communications network, the method comprising: selecting from a plurality of system configurations, by a performance measurement module, a system configuration on the parallel computer for executing the collective operation; executing, by the performance measurement module, the collective operation on the selected system configuration on the parallel computer; determining, by the performance measurement module, performance metrics associated with executing the collective operation on the selected system configuration on the parallel computer; selecting, by the performance measurement module using a simulated annealing algorithm, a plurality of test system configurations on the parallel computer for executing the collective operation, wherein the simulated annealing algorithm specifies a similarity threshold between the plurality of test system configurations and the selected system configuration; executing, by the performance measurement module, the collective operation on each of the test system configurations; determining, by the performance measurement module, performance metrics associated with executing the collective operation on each of the test system configurations; and identifying, by the performance measurement module, a preferred system configuration in dependence upon performance metrics associated with each system configuration of the plurality of test system configurations.