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

随着多核处理器对存储器性能的要求越来越高，存储器子系统已经成为继处理器和硬盘驱动器之后的又一个热问题。 为了应对这一挑战，必须开发出平滑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存储器热模型和模拟工具。该项目提出了DRAM存储器子系统的存储器热模型和热模拟器，以及有效的DTM（动态热管理）方法。 研究人员开发了一个简单而准确的动态热模型的基础上完全缓冲的DIMM和一个准确而快速的两级模拟器估计内存子系统的热行为。 他们还研究了几种新的系统级DTM方案，这些方案将DRAM热管理与处理器性能调节相协调。 几种新的DTM方法有待开发。 第一种方法是自适应核心门控，根据内存热状态调整活动核心的数量;第二种方法是协调DVFS（动态电压和频率缩放），在内存热紧急情况下主动降低处理器频率和电压，从而减少DRAM发热和处理器功耗。 此外，热感知OS作业调度通过适当地混合具有不同存储器需求的作业来平滑存储器流量和DRAM热量生成。 在硬件平台上验证了热模型的执行;并在真实的系统上对所提出的方法进行了评估。

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.