Cross-ISA execution of SIMD regions for improved performance

Abstract

We investigate the effectiveness of executing SIMD workloads on multiprocessors with heterogeneous Instruction Set Architecture (ISA) cores. Heterogeneous ISAs offer an intriguing clock speed/parallelism tradeoff for workloads with frequent usage of SIMD instructions. We consider dynamic migration of SIMD and non-SIMD workloads across ISA-different cores to exploit this trade-off. We present the necessary modifications for a general compiler/run-time infrastructure to transform the dynamic program state of SIMD regions at run-time from one ISA format to another for cross-ISA migration and execution. Additionally, we present a SIMD-aware scheduling policy that makes cross-ISA migration decisions that improve system throughput. We prototype a heterogeneous-ISA system using an Intel Xeon x86-64 server and a Cavium ThunderX ARMv8 server and evaluate the effectiveness of our infrastructure and scheduling policy. Our results reveal that cross-ISA execution migration within SIMD regions can yield throughput gains up to 36% compared to traditional homogeneous ISA systems.