Redefining the Role of the CPU in the Era of CPU-GPU Integration

We've seen the quick adoption of GPUs as general-purpose computing engines in recent years, fueled by high computational throughput and energy efficiency. There is heavier integration of the CPU and GPU, including the GPU appearing on the same die, further decreasing barriers to the use of the GPU to offload the CPU. Much effort has been made to adapt GPU designs to anticipate this new partitioning of the computation space, including better programming models and more general processing units with support for control flow. However, researchers have placed little attention on the CPU and how it must adapt to this change. This article demonstrates that the coming era of CPU and GPU integration requires us to rethink the CPU's design and architecture. We show that the code the CPU will run, once appropriate computations are mapped to the GPU, has significantly different characteristics than the original code (which previously would have been mapped entirely to the CPU).