Instruction execution trade-offs for SIMD vs. MIMD vs. mixed modeparallelism

摘要

Mixed-mode parallel processors can quickly switch from executinginstructions in single instruction, multiple data stream (SIMD) mode toexecuting them in multiple instruction, multiple data stream (MIMD)mode. To fully exploit this capability, the circumstances under whicheach mode should be used must be understood. This paper exploresmixed-mode parallelism by presenting a general overview of thetrade-offs between SIMD and MIMD modes, and then characterizing indetail three of the trade-offs concerning instruction executionperformance. These include the effect of overlapping control unit andprocessor execution in SIMD mode, performance of conditional statements,and the consequences of switching parallelism modes