Compiler Enhanced Scheduling for OpenMP for Heterogeneous Multiprocessors

Abstract: Scheduling in Asymmetric Multicore Processors (AMP), a special case of Heterogeneous Multiprocessors, is a widely studied topic. The scheduling techniques which are mostly runtime do not usually consider parallel programming pattern used in parallel programming frameworks like OpenMP. On the other hand, current compilers for these parallel programming platforms are hardware oblivious which prevent any compile-time optimization for platforms like big.LITTLE and has to completely rely on runtime optimization. In this paper, we propose a hardware-aware Compiler Enhanced Scheduling (CES) where the common compiler transformations are coupled with compiler added scheduling commands to take advantage of the hardware asymmetry and improve the runtime efficiency. We implement a compiler for OpenMP and demonstrate its efficiency in Samsung Exynos with big.LITTLE architecture. On an average, we see 18% reduction in runtime and 14% reduction in energy consumption in standard NPB and FSU benchmarks with CES across multiple frequencies and core configurations in big.LITTLE.