Express Read in MLC Phase Change Memories
Express Read in MLC Phase Change Memories
复制标题
MLC 相变存储器中的快速读取
DOI：
10.1145/3177876
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
H. Sarbazi
中科院分区：
文献类型：
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作者：
Majid Jalili;H. Sarbazi
在大数据时代，必须增强计算机系统的能力，以支持2.5万亿字节/天的数据传输。在计算机系统的组件中，主存对系统的整体性能有很大影响。在过去的40年里，DRAM技术一直被用来构建主存储器。然而，DRAM技术的可扩展性面临着严峻的挑战。为了跟上不断增长的对更大主存的需求，已经引入了一些新的替代技术。相变存储器(PCM)被认为是替代DRAM的技术之一。PCM提供了一些值得注意的特性，如低静态功耗、非易失性以及每个单元(多级单元或MLC)存储一位以上的能力。然而，PCM(特别是MLC PCM)的短寿命和长访问延迟需要可行和有效的解决方案。在本文中，基于应用程序访问大量读友好数据块的观察，我们提出了Express Read，以防止MLC PCM读取电路花费不必要的时间来感测内存块的单元。读取友好的数据块(RFDB)仅由“11”和“00”位对组成，因此在感测到单元的最高有效位时，可以提前终止读取操作，以减少MLC读取时间和功耗。此外，我们使用两种简单的技术来增加RFDB的数量，以更好地利用Express Read的优势。全系统模拟的结果表明，与基准系统相比，性能平均提高了6%，能量平均提高了21%。
In the era of big data, the capability of computer systems must be enhanced to support 2.5 quintillion byte/day data delivery. Among the components of a computer system, main memory has a great impact on overall system performance. DRAM technology has been used over the past four decades to build main memories. However, the scalability of DRAM technology has faced serious challenges. To keep pace with the ever-increasing demand for larger main memory, some new alternative technologies have been introduced. Phase change memory (PCM) is considered as one of such technologies for substituting DRAM. PCM offers some noteworthy properties such as low static power consumption, nonvolatility, and capability of storing more than one bit per cell (multilevel cell, or MLC). However, the short lifetime and long access latency of PCM (specifically MLC PCM) require feasible and efficient solutions. In this article, based on the observation that applications access a significant number of read-friendly data blocks, we propose Express Read to prevent the MLC PCM read circuit to spend unnecessary time sensing the cells of a memory block. A read-friendly data block (RFDB) is composed of only “11” and “00” bit pairs, and thus upon sensing the most significant bit of a cell, the read operation can be early terminated to reduce the MLC read time and power consumption. Moreover, we increase the number of RFDBs using two simple techniques to better exploit the benefits of Express Read. Results obtained from full-system simulation near 6% performance improvement and 21% energy gain, on average, over the baseline system.