NGraph: Parallel Graph Processing in Hybrid Memory Systems

Abstract

Big data applications like graph processing are highly imposed on memory capacity. Byte-addressable non-volatile memory (NVM) technologies can offer much larger memory capacity, lower cost per bit relative to traditional DRAM. They are expected to play a crucial role in mitigating I/O operations for big data processing. However, since the NVMs show higher access latency and lower bandwidth compared with DRAM, it is still challenging to fully exploit the advantages of both the DRAM and NVM for graph processing. In this paper, we propose NGraph, a new parallel graph processing framework specially designed for hybrid memory systems. According to different access patterns of graph data, NGraph exploits memory heterogeneity-aware data placement strategies to avoid random accesses and frequent updates to NVM. NGraph partitions graph by destination vertices and exploits a task decomposition scheme to avoid data contention between multicores. Meanwhile, the NGraph balances the execution time of parallel graph data processing on multicores through a work-stealing strategy. Moreover, the NGraph also proposes software-based data pre-fetching to improve cache hit rate, and supports huge page to reduce address translation overhead. We evaluate NGraph using a hybrid memory emulator. The experimental results show that NGraph can achieve up to 48.28% performance improvement for several typical benchmarks compared with the state-of-the-art systems Ligra and Polymer.