The present invention provides a new method and system to provide a flexible and easily reconfigurable way to map threads or tasks of a parallel program to CPUs of a parallel computer. The inventive method replaces the necessity of coding the mapping of threads or tasks to CPUs in the parallel computer by looking up in a mapping description which is preferably presented in form of least one table that is provided at runtime. The mapping description specifies various mapping strategies of tasks or threads to CPUs. Selecting of a certain mapping strategy or switching from a specified mapping strategy to a new one can be done manually or automatically at runtime without any decompilation of the parallel program.