Performance evaluation of the PowerPC 620 microarchitecture

The PowerPC 620™ microprocessor is the most recent and performance leading member of the PowerPC™ family. The 64-bit PowerPC 620 microprocessor employs a two-phase branch prediction scheme, dynamic renaming for all the register files, distributed multi-entry reservation stations, true out-of-order execution by six execution units, and a completion buffer for ensuring precise exceptions. This paper presents an instruction-level performance evaluation of the 620 microarchitecture. A performance simulator is developed using the VMW (Visualization-based Microarchitecture Workbench) retargetable framework. The VMW-based simulator accurately models the microarchitecture down to the machine cycle level. Extensive trace-driven simulation is performed using the SPEC92 benchmarks. Detailed quantitative analyses of the effectiveness of all key microarchitecture features are presented.