TURBULENCE: Complexity-effective Out-of-order Execution on GPU with Distance-based ISA

A graphic processing unit (GPU) is a processor that achieves high throughput by exploiting data parallelism. We found that many GPU workloads also contain instruction-level parallelism, which can be extracted through out-of-order execution to provide additional performance improvement opportunities. We propose the TURBULENCE architecture for very low-cost out-of-order execution on GPUs. TURBULENCE consists of 1) a novel ISA that introduces the concept of referencing operands by inter-instruction distance instead of register numbers and 2) a novel microarchitecture that executes the novel ISA. Our proposed ISA and microarchitecture enable cost-effective out-of-order execution on GPUs without introducing expensive hardware.