Abstract: Methods and apparatus, including computer program products, for measuring the performance of aspects of a complex data processing system. In one aspect, a method uses a dynamic synthetic benchmark to provide performance information for a program application running on a virtual machine. The benchmark in one implementation uses a load profile that includes information about instructions that make up the application, their call frequencies, and their workloads. Microbenchmarks of individual virtual machine instructions provide performance information about the virtual machine that is used with the load profile to synthesize a performance benchmark for the application.