Collaborative Research: CSR --- SMA: Thermal Modeling, Simulation and Management of Memory Subsystems for Multi-Core Systems

随着多核处理器对高存储性能的要求，存储子系统成为继处理器和硬盘之后新的热点问题。为了迎接这一挑战，必须开发出平稳高效的存储器热管理方案。在公共领域也缺乏用于研究和教育的记忆、热模型和模拟工具。该项目提出了用于DRAM存储子系统的存储热模型和热模拟器，以及高效的DTM(动态热管理)方法。研究人员开发了一个基于全缓冲DIMM的简单而准确的动态热模型和一个准确而快速的两级模拟器来估计存储子系统的热行为。他们还研究了几个新的系统级DTM方案，这些方案将DRAM热管理与处理器性能节流相协调。将开发几种新的数字地面模型方法。第一种方法是自适应核门，它根据内存的热状态来调整活跃核的数量；第二种是协调的DVFS(动态电压和频率调节)方法，它在内存过热时主动降低处理器的频率和电压，从而同时减少DRAM的发热量和处理器的功耗。此外，热感知操作系统作业调度通过适当地混合具有不同内存需求的作业来平滑内存流量和DRAM热量生成。热模型在硬件平台上得到了验证，所提出的方法在真实系统上进行了评估。

With the demand for high memory performance from multi-core processors, memory subsystem has become a new thermal concern after processor and hard drive. Smooth and efficient memory thermal management schemes must be developed to meet the challenge. There also lack memory thermal models and simulation tools in the public domain for research and education. This project proposes memory thermal models and thermal simulators for DRAM memory subsystems as well as efficient DTM (dynamic thermal management) methods. The investigators develop a simple and accurate dynamic thermal model based on fully buffered DIMM and an accurate and fast two-level simulator estimating the thermal behavior of a memory subsystem. They also study several new, system-level DTM schemes that coordinate DRAM thermal management with processor performance throttling. Several new DTM methods are to be developed. The first method, Adaptive Core Gating, adjusts the number of active cores according to the memory thermal status.The second method, Coordinated DVFS (dynamic voltage and frequency scaling), proactively scales down the processor frequency and voltage upon memory thermal emergency, reducing both the DRAM heat generation and the processor power consumption. Furthermore, thermal-aware OS job scheduling smoothes memory traffic and DRAM heat generation by mixing jobs with different memory demands appropriately. The thermal model is validated to execution on hardware platforms; and the proposed methods are evaluated on real systems.