NVCache: A Plug-and-Play NVMM-based I/O Booster for Legacy Systems

This paper introduces NVCACHE, an approach that uses a non-volatile main memory (NVMM) as a write cache to improve the write performance of legacy applications. We compare NVCACHE against file systems tailored for NVMM (Ext4-DAX and NOVA) and with I/O-heavy applications (SQLite, RocksDB). Our evaluation shows that NVCACHE reaches the performance level of the existing state-of-the-art systems for NVMM, but without their limitations: NVCACHE does not limit the size of the stored data to the size of the NVMM, and works transparently with unmodified legacy applications, providing additional persistence guarantees even when their source code is not available.

I. Introduction

NVMM is a type of memory that preserves its content upon power loss, is byte-addressable and achieves orders of magnitude better performance than flash memory. NVMM essentially provides persistence with the performance of a volatile memory [30]. Examples of NVMM include phase change memory (PCM) [14], [24], [38], [39], [11], resistive RAM (ReRAM) [8], crossbar RAM [32], memristor [58] and, more recently, Intel 3D XPoint [27], [41], [6], [5].