As the scaling of applications increases, the demand of main memory capacity increases in order to serve large working set. It is difficult for DRAM （dynamic random access memory） based memory system to satisfy the ...As the scaling of applications increases, the demand of main memory capacity increases in order to serve large working set. It is difficult for DRAM （dynamic random access memory） based memory system to satisfy the memory capacity requirement due to its limited scalability and high energy consumption. Compared to DRAM, PCM （phase change memory） has better scalability, lower energy leakage, and non-volatility. PCM memory systems have become a hot topic of academic and industrial research. However, PCM technology has the following three drawbacks： long write latency, limited write endurance, and high write energy, which raises challenges to its adoption in practice. This paper surveys architectural research work to optimize PCM memory systems. First, this paper introduces the background of PCM. Then, it surveys research efforts on PCM memory systems in performance optimization, lifetime improving, and energy saving in detail, respectively. This paper also compares and summarizes these techniques from multiple dimensions. Finally, it concludes these optimization techniques and discusses possible research directions of PCM memory systems in future.展开更多
Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the...Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the well-known equilibrium hexagonal Sb2Te3 crystal, we prove the metastable face-centered cubic Sb2Te3 phase does exist. Such a metastable crystal contains a large concentration of vacancies randomly occupying the cationic lattice sites. The face-centered cubic to hexagonal phase transformation of Sb2Te3, accompanied by vacancy aggregation, occurs at a quite lower temperature compared to that of Ge2Sb2Te5 alloy. We prove that the covalent-like bonds prevail in the metastable Sb2Te3 crystal, deviating from the ideal resonant features. If a proper doping technique is adopted, the metastable Sb2Te3 phase could be promising for realizing reversibly swift and low-energy phase change memory applications. Our study may offer a new insight into commercialized Ge-Sb-Te systems and help in the design of novel phase change materials to boost the performances of the phase change memorv device.展开更多
并行I/O技术有效优化了I/O性能,但对访问延迟却难以控制.相变存储器(phase change memory,PCM)作为一种SCM(storage class memory),具有非易失性、随机可读写、低延迟、高吞吐率、体积小和低功耗的特点,为I/O性能优化提供了最直接有效...并行I/O技术有效优化了I/O性能,但对访问延迟却难以控制.相变存储器(phase change memory,PCM)作为一种SCM(storage class memory),具有非易失性、随机可读写、低延迟、高吞吐率、体积小和低功耗的特点,为I/O性能优化提供了最直接有效的途径.研究了PCM的特性与存在的问题,总结了目前PCM的应用研究进展,针对高性能计算中的并行I/O问题,提出了一种基于相变存储器PCM的层次式并行混合存储模型,能够有效提高并行文件系统元数据服务效率和并行I/O吞吐率.展开更多
基金This work was supported by the National Basic Research 973 Program of China under Grant No. 2011CB302502, the National Natural Science Foundation of China under Grant No. 61379042, Huawei Research Program under Grant No. YB2013090048, and the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No. XDA06010401.
文摘As the scaling of applications increases, the demand of main memory capacity increases in order to serve large working set. It is difficult for DRAM （dynamic random access memory） based memory system to satisfy the memory capacity requirement due to its limited scalability and high energy consumption. Compared to DRAM, PCM （phase change memory） has better scalability, lower energy leakage, and non-volatility. PCM memory systems have become a hot topic of academic and industrial research. However, PCM technology has the following three drawbacks： long write latency, limited write endurance, and high write energy, which raises challenges to its adoption in practice. This paper surveys architectural research work to optimize PCM memory systems. First, this paper introduces the background of PCM. Then, it surveys research efforts on PCM memory systems in performance optimization, lifetime improving, and energy saving in detail, respectively. This paper also compares and summarizes these techniques from multiple dimensions. Finally, it concludes these optimization techniques and discusses possible research directions of PCM memory systems in future.
基金This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences （No. XDA09020402）, National Integrate Circuit Research Program of China （No. 2009ZX02023-003）, National Natural Science Foundation of China （Nos. 61076121, 61176122, 61106001, 61261160500, and 61376006）, Science and Technology Council of Shanghai （Nos. 13ZR1447200 and 13DZ2295700）. The supercomputer time was provided by the National Supercomputer Center in Tianjin, and the calculations were performed on TianHe-1 （A）.
文摘Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the well-known equilibrium hexagonal Sb2Te3 crystal, we prove the metastable face-centered cubic Sb2Te3 phase does exist. Such a metastable crystal contains a large concentration of vacancies randomly occupying the cationic lattice sites. The face-centered cubic to hexagonal phase transformation of Sb2Te3, accompanied by vacancy aggregation, occurs at a quite lower temperature compared to that of Ge2Sb2Te5 alloy. We prove that the covalent-like bonds prevail in the metastable Sb2Te3 crystal, deviating from the ideal resonant features. If a proper doping technique is adopted, the metastable Sb2Te3 phase could be promising for realizing reversibly swift and low-energy phase change memory applications. Our study may offer a new insight into commercialized Ge-Sb-Te systems and help in the design of novel phase change materials to boost the performances of the phase change memorv device.
文摘并行I/O技术有效优化了I/O性能,但对访问延迟却难以控制.相变存储器(phase change memory,PCM)作为一种SCM(storage class memory),具有非易失性、随机可读写、低延迟、高吞吐率、体积小和低功耗的特点,为I/O性能优化提供了最直接有效的途径.研究了PCM的特性与存在的问题,总结了目前PCM的应用研究进展,针对高性能计算中的并行I/O问题,提出了一种基于相变存储器PCM的层次式并行混合存储模型,能够有效提高并行文件系统元数据服务效率和并行I/O吞吐率.
