The EDPEPPS toolset is the fruit of a 10 man-year-research development and integrates many modules in order to predict and classify the execution times of C/PVM programs mapped on a cluster of heterogeneous workstations. In this project, a performance characterization tool called Chronos has been developed to model the processor and C instructions. Chronos can be used to characterize a wide range of machines as it is developed round a specialized benchmark. Chronos uses a parameter-based model and characterizes the machine and the program studied. Then, the execution predictor evaluates the time spent in each program block, according to a generic model of cache memory which simulates most of the CPU internal cache memory architecture. Chronos does not need any user’s intervention as all the operations are automatic. The performance accuracy of Chronos is highlighted by a real processor-consuming sequential example.\parThis tool can be used by designers to predict the average execution time of their applications quickly. Average percentage errors obtained from this tool are below 10%.