Empirical Study of NVM Storage: An Operating System's Perspective and Implications

摘要

As high performance NVM storage such as PCM and STT-RAM emerge, legacy software layers optimized for HDDs should be revisited. Specifically, as storage performance approaches DRAM performance, existing I/O mechanisms and software configurations should be reassessed. This paper explores the challenges and implications of using NVM storage with a broad range of experiments. We measure the performance of a system with NVM storage emulated by DRAM with proper timing parameters and compare it with that of HDD storage environments under various configurations. Our experimental results show that even with storage as fast as DRAM, the performance gain is not large for read operations as current I/O mechanisms do a good job of hiding the slow performance of HDD. To assess the potential benefit of fast storage media, we change various I/O configurations and perform experiments to quantify the effects of existing I/O mechanisms such as buffer caching, read-ahead, synchronous I/O, direct I/O, block I/O, and byte-addressable I/O on systems with NVM storage. We also investigate some unique performance characteristics of NVM in comparison with HDD by changing the number of accesses and the amount of data to be transferred. We anticipate that our results will provide directions in system software development in presence of ever faster storage devices.