A performance and cost analysis of applying superscalar method to mainframe computers

The paper presents the results of evaluating the increased performance and cost of mainframe computers with superscalar architectures. Since mainframe users demand object compatibility, we assume the same object as that of nonsuperscalar machines. We compared four differently configured superscalar machines based on Hitachi's high end mainframe computer, the HITAC M-880, varying the multiplicity of operand accessibility and arithmetic capability. In estimating performance, we considered the effect of critical path delay on machine cycle time. For scientific jobs, either dual operand accessibility or dual arithmetic capability, or both, improved performance (MIPS) by 11-28% while increasing CPU hardware cost by 2-21%. For online transaction processing (OLTP), no configuration increased performance more than 4%. To make the superscalar architecture more effective for OLTP, it is important to reduce execution cycles per instruction (CPI), by reducing overhead caused by sequential processes.< >