arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1805.03048cs.AR
收藏

Tiered-Latency DRAM:以低成本实现低延迟主存

Tiered-Latency DRAM: Enabling Low-Latency Main Memory at Low Cost

Donghyuk Lee, Yoongu Kim, Vivek Seshadri, Jamie Liu, Lavanya Subramanian, Onur Mutlu

摘要:

本文总结了在HPCA 2013上发表的分层延迟DRAM(TL-DRAM)的思想,并探讨了这项工作的意义和未来的潜力。DRAM的容量和每比特成本在历史上已经缩放以满足日益庞大和复杂的计算机系统的需要。然而,DRAM延迟几乎保持不变,使得存储器延迟成为当今系统中的性能瓶颈。我们观察到,高访问延迟不是DRAM固有的,而是为了降低每位成本而做出的权衡。为了减轻DRAM感测结构的高面积开销,商品DRAM通过称为DRAM的导线将许多DRAM单元连接到每个感测放大器。这些位线由于其长的长度而具有高寄生电容,并且该寄生电容是DRAM延迟的主要来源。专用的低延迟DRAM使用具有较少单元的较短位线,但由于较大的读出放大器面积开销而具有较高的每位成本。为了实现低延迟和低每位成本,我们引入了分层延迟DRAM(TL-DRAM)。在TL-DRAM中,每个长DRAM被隔离晶体管分成两个较短的段,允许以短DRAM的延迟访问两个段中的一个,而不会导致每比特的高成本。我们提出的机制,使用低延迟段作为硬件管理或软件管理的缓存。我们的评估表明,我们提出的机制提高了单核和多编程工作负载的性能和能源效率。分层延迟DRAM启发了其他几项减少DRAM延迟的工作,几乎没有架构修改。

英文摘要:

This paper summarizes the idea of Tiered-Latency DRAM (TL-DRAM), which was published in HPCA 2013, and examines the work's significance and future potential. The capacity and cost-per-bit of DRAM have historically scaled to satisfy the needs of increasingly large and complex computer systems. However, DRAM latency has remained almost constant, making memory latency the performance bottleneck in today's systems. We observe that the high access latency is not intrinsic to DRAM, but a trade-off is made to decrease the cost per bit. To mitigate the high area overhead of DRAM sensing structures, commodity DRAMs connect many DRAM cells to each sense amplifier through a wire called a bitline. These bit-lines have a high parasitic capacitance due to their long length, and this bitline capacitance is the dominant source of DRAM latency. Specialized low-latency DRAMs use shorter bitlines with fewer cells, but have a higher cost-per-bit due to greater sense amplifier area overhead. To achieve both low latency and low cost per bit, we introduce Tiered-Latency DRAM (TL-DRAM). In TL-DRAM, each long bitline is split into two shorter segments by an isolation transistor, allowing one of the two segments to be accessed with the latency of a short-bitline DRAM without incurring a high cost per bit. We propose mechanisms that use the low-latency segment as a hardware-managed or software-managed cache. Our evaluations show that our proposed mechanisms improve both performance and energy efficiency for both single-core and multiprogrammed workloads. Tiered-Latency DRAM has inspired several other works on reducing DRAM latency with little to no architectural modification.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑