HOOP: Efficient Hardware-Assisted Out-of-Place Update for Non-Volatile Memory

Byte-addressable non-volatile memory (NVM) is a promising technology that provides near-DRAM performance with scalable memory capacity. However, it requires atomic data durability to ensure memory persistency. Therefore, many techniques, including logging and shadow paging, have been proposed. However, most of them either introduce extra write traffic to NVM or suffer from significant performance overhead on the critical path of program execution, or even both. In this paper, we propose a transparent and efficient hardware-assisted out-of-place update (HOOP) mechanism that supports atomic data durability, without incurring much extra writes and performance overhead. The key idea is to write the updated data to a new place in NVM, while retaining the old data until the updated data becomes durable. To support this, we develop a lightweight indirection layer in the memory controller to enable efficient address translation and adaptive garbage collection for NVM. We evaluate HOOP with a variety of popular data structures and data-intensive applications, including key-value stores and databases. Our evaluation shows that HOOP achieves low critical-path 1atency with small write amplification, which is close to that of a native system without persistence support. Compared with state-of-the-art crash-consistency techniques, it improves application performance by up to 1.7×, while reducing the write amplification by up to 2.1×. HOOP also demonstrates scalable data recovery capability on multi-core systems.