Oversubscribing GPU Unified Virtual Memory

Abstract

Recent GPU architectures support unified virtual memory (UVM), which offers great opportunities to solve larger problems by memory oversubscription. Although some studies are concerned over the performance degradation under UVM oversubscription, the reasons behind workloads' diverse sensitivities to oversubscription is still unclear. In this work, we take the first step to select various benchmark applications and conduct rigorous experiments on their performance under different oversubscription ratios. Specifically,we take into account the variety of memory access patterns and explain applications' diverse sensitivities to oversubscription. We also consider prefetching and UVM hints, and discover their complex impact under different oversubscription ratios. Moreover, the strengths and pitfalls of UVM's multi-GPU support are discussed. We expect that this paper will provide useful experiences and insights for UVM system design.