SIMT-X

Abstract

This work introduces Single Instruction Multi-Thread Express (SIMT-X), a general-purpose Central Processing Unit (CPU) microarchitecture that enables Graphics Processing Units (GPUs)-style SIMT execution across multiple threads of the same program for high throughput, while retaining the latency benefits of out-of-order execution, and the programming convenience of homogeneous multi-thread processors. SIMT-X leverages the existing Single Instruction Multiple Data (SIMD) back-end to provide CPU/GPU-like processing on a single core with minimal overhead. We demonstrate that although SIMT-X invokes a restricted form of Out-of-Order (OoO), the microarchitecture successfully captures a majority of the benefits of aggressive OoO execution using at most two concurrent register mappings per architectural register, while addressing issues of partial dependencies and supporting a general-purpose Instruction Set Architecture (ISA).