Supporting GPU Sharing in Cloud Environments with a Transparent Runtime Consolidation Framework

Driven by the emergence of GPUs as a major player in high performance computing and the rapidly growing popularity of cloud environments, GPU instances are now being offered by cloud providers. The use of GPUs in a cloud environment, however, is still at initial stages, and the challenge of making GPU a true shared resource in the cloud has not yet been addressed. This paper presents a framework to enable applications executing within virtual machines to transparently share one or more GPUs. Our contributions are twofold: we extend an open source GPU virtualization software to include efficient GPU sharing, and we propose solutions to the conceptual problem of GPU kernel consolidation. In particular, we introduce a method for computing the affinity score between two or more kernels, which provides an indication of potential performance improvements upon kernel consolidation. In addition, we explore molding as a means to achieve efficient GPU sharing also in the case of kernels with high or conflicting resource requirements. We use these concepts to develop an algorithm to efficiently map a set of kernels on a pair of GPUs. We extensively evaluate our framework using eight popular GPU kernels and two Fermi GPUs. We find that even when contention is high our consolidation algorithm is effective in improving the throughput, and that the runtime overhead of our framework is low.