NURA: A Framework for Supporting Non-Uniform Resource Accesses in GPUs.

Multi-application execution in Graphics Processing Units (GPUs), a promising way to utilize GPU resources, is still challenging. Some pieces of prior work (e.g., spatial multitasking) have limited opportunity to improve resource utilization, while other works, e.g., simultaneous multi-kernel, provide fine-grained resource sharing at the price of unfair execution. This paper proposes a new multi-application paradigm for GPUs, called NURA, that provides high potential to improve resource utilization and ensures fairness and Quality-of-Service (QoS). The key idea is that each streaming multiprocessor (SM) executes Cooperative Thread Arrays (CTAs) belong to only one application (similar to the spatial multi-tasking) and shares its unused resources with the SMs running other applications demanding more resources. NURA handles resource sharing process mainly using a software approach to provide simplicity, low hardware cost, and flexibility. We also perform some hardware modifications as an architectural support for our software-based proposal. We conservatively analyze the hardware cost of our proposal, and observe less than 1.07% area overhead with respect to the whole GPU die. Our experimental results over various mixes of GPU workloads show that NURA improves GPU system throughput by 26% compared to state-of-the-art spatial multi-tasking, on average, while meeting the QoS target. In terms of fairness, NURA has almost similar results to spatial multitasking, while it outperforms simultaneous multi-kernel by an average of 76%.