Phase change memory (PCM) recently has emerged as a promising technology to meet the fast growing demand for large capacity main memory in modern computing systems. Multi-level cell (MLC) PCM storing multiple bits in a single cell offers high density with low per-byte fabrication cost. However, PCM suffers from long write latency, short cell endurance, limited write throughput and high peak power, which makes it challenging to be integrated in the memory hierarchy.ududTo address the long write latency, I propose write truncation to reduce the number of write iterations with the assistance of an extra error correction code (ECC). I also propose form switch (FS) to reduce the storage overhead of the ECC. By storing highly compressible lines in single level cell (SLC) form, FS improves read latency as well. ududTo attack the short cell endurance and large peak power, I propose elastic RESET (ER) to construct triple-level cell PCM. By reducing RESET energy, ER significantly reduces peak power and prolongs PCM lifetime. ududTo improve the write concurrency, I propose fine-grained write power budgeting (FPB) observing a global power budget and regulates power across write iterations according to the step-down power demand of each iteration. A global charge pump is also integrated onto a DIMM to boost power for hot PCM chips while staying within the global power budget. ududTo further reduce the peak power, I propose intra-write RESET scheduling distributing cell RESET initializations in the whole write operation duration, so that the on-chip charge pump size can also be reduced.
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机译:相变存储器(PCM)最近已成为一种有前途的技术,可以满足现代计算系统中对大容量主存储器快速增长的需求。在单个单元中存储多个位的多级单元(MLC)PCM提供了高密度,而每字节的制造成本却很低。但是,PCM具有较长的写入延迟,较短的单元寿命,有限的写入吞吐量和较高的峰值功率,这使其很难集成到存储器层次结构中。 ud ud为了解决较长的写入延迟,我建议采用写入截断的方法来减少借助额外的纠错码(ECC)进行的写迭代次数。我还建议使用表格切换(FS)来减少ECC的存储开销。通过以单级单元(SLC)形式存储高度可压缩的行,FS还可以改善读取延迟。 ud ud为了攻击电池寿命短和峰值功率大的问题,我建议使用弹性复位(ER)来构造三级电池PCM。通过降低RESET能量,ER可以显着降低峰值功率并延长PCM寿命。 ud ud为了改善写入并发性,我提出了细粒度的写入功率预算(FPB),它遵循全局功率预算,并根据每次迭代的降压功率需求来调节整个写入迭代的功率。全局电荷泵也集成到DIMM中,以提高热PCM芯片的功率,同时保持在全局功率预算之内。为了进一步降低峰值功率,我建议在整个写操作期间内进行写内RESET调度,以分配单元RESET初始化,从而也可以减小片上电荷泵的尺寸。
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