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 others, 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 ensure fairness and Quality-of-Service(QoS). The key idea is that each streaming multiprocessor (SM) executes the Cooperative Thread Arrays (CTAs) that belong to only one application (similar to 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 overhead, and flexibility.We also perform some hardware modifications as an architectural support for our software-based proposal. Our conservative analysis reveals that the hardware area overhead of our proposal is less than 1.07% with respect to the whole GPU die. Our experimental results over various mixes of GPU workloads show that NURA improves throughput by 26% compared to the state-of-the-art spatial multi-tasking, on average, while meeting QoS targets. In terms of fairness, NURA has almost similar results to spatial multitasking, while it outperforms simultaneous multi-kernel by 76%, on average.