PageCmp: Bandwidth Efficient Page Deduplication through In-memory Page Comparison

KSM-based page deduplication is an important Linux system service for reducing main memory consumption on cloud servers. However, it tends to incur large computation and memory bandwidth overheads. Recently proposed hardware-assisted KSM approaches, while effectively addressing the computation overhead, still need to consume a dramatic amount of off-chip memory bandwidth. In this paper, we propose PageCmp, a PIM (Processing-In-Memory) based page deduplication approach, to achieve bandwidth efficiency on cloud servers. PageCmp exploits the bitwise operation capability inside the DRAM cell array to enable fast page comparison. By integrating a lightweight local comparator inside the output buffer of DRAM modules, PageCmp sends only the page comparison result back to the processor. Our experimental results show that, comparing to the state-of-the-art, PageCmp achieves 4x memory bandwidth reduction while introducing less than 1% hardware overhead.