Exploring new features of high-bandwidth memory for GPUs

Abstract

Due to the off-chip I/O pin and power constraints of GDDR5, HBM has been proposed to provide higher bandwidth and lower power consumption for GPUs. In this paper, we first provide detailed comparison between HBM and GDDR5 and expose two unique features of HBM: dual-command and pseudo channel mode. Second, we analyze the effectiveness of these two features and show that neither notably contributes to performance. However, by combining pseudo channel mode with cache architecture supporting fine-grained cache-line management such as Amoeba cache, we achieve high effciency for applications with irregular memory requests. Our experiment demonstrates that compared with Amoeba caches with legacy mode, Amoeba cache with pseudo channel mode improves GPU performance by 25% and reduces HBM energy consumption by 15%.