The advent of heterogeneous multi-core architectures brought with it huge benefits to energy efficiency by running programs on properly-sized cores. Modern heterogeneous multi-core systems as suggested by Artjom et al. schedule tasks to different cores based on governors that may optimize a task for energy use or performance. This provides benefits to the system as a whole in reducing energy costs where possible, but also not compromising on performance for timing-critical applications. In the era of dark silicon, energy optimization is increasingly important, and many architectures have arisen that seek to optimize processors to specific tasks, often at the cost of generality. We propose that we can still achieve energy-saving and potentially performance-improving benefits while not affecting a system's generality at all, by achieving heterogeneity at the level of Arithmetic logic unit (ALUs). Much like a heterogeneous multi-core system achieves benefits from its heterogeneity and efficient scheduling, a heterogeneous ALU system can achieve similar benefits by routing ALU operations to properly sized ALUs. Additionally much like there are scheduling modes for the governors of heterogeneous multi-core processors, we propose that energy-constrained modes can be effective in a heterogeneous ALU system with the routing of operations to smaller ALUs for immense energy savings. We examine the energy and performance characteristics of scaling ripple carry adders and evaluate the total energy and performance benefits of such a system when running applications. With our proposed controls, input operand size-based and energy constraint-based, we could potentially emulate the success of heterogeneous processor task scheduling at a finer-grained level. This paper presents our evaluation of the potential of heterogeneous ALU processors.

翻译：异构多核架构的出现通过将程序运行在适当大小的核心上，为能效带来了巨大好处。正如Artjom等人所建议的，现代异构多核系统基于调节器将任务调度到不同核心，这些调节器可针对能耗或性能优化任务。这有助于整个系统在可能的情况下降低能耗，同时不对时序关键型应用的性能造成妥协。在暗硅时代，能耗优化日益重要，许多架构应运而生，旨在针对特定任务优化处理器，但往往以牺牲通用性为代价。我们提出，通过在不影响系统通用性的前提下，在算术逻辑单元（ALU）层面实现异构性，我们仍能实现节能乃至性能提升的好处。正如异构多核系统从其异构性和高效调度中获益一样，异构ALU系统可以通过将ALU运算路由到适当大小的ALU来获得类似的好处。此外，正如异构多核处理器的调节器有多种调度模式，我们提出在异构ALU系统中，能耗受限模式可通过将运算路由到更小的ALU来实现巨大的节能效果。我们研究了不同规模行波进位加法器的能耗和性能特性，并评估了此类系统在运行应用程序时的总能耗和性能收益。通过我们提出的基于输入操作数大小和能耗约束的控制机制，我们有望在更细粒度层面上复现异构处理器任务调度的成功。本文展示了我们对异构ALU处理器潜力的评估。