The paper is devoted to analysis of a strategy of computation distribution on heterogeneous parallel systems. According to this strategy processes of parallel program are distributed over the processors according to their performances and data are distributed between processes evenly. The paper presents an algorithm that computes optimal number of the processes and their distribution over processors minimizing the execution time of an application. The processor performance is considered as a function of the number of processes running on the processor and the amount of the data processing by the processor.