论文标题
彩虹：多芯片服务器的可组合连贯协议
Rainbow: A Composable Coherence Protocol for Multi-Chip Servers
论文作者
论文摘要
使用多芯片模块（MCM）和/或多插座板的使用是增加服务器计算密度同时保持芯片收益率的最合适方法。本文在此类系统中介绍了一种新的连贯协议，适用于复杂性和可扩展性。该提案使用两个互补的想法：（1）通过彩色计数将复杂性从性能中解散的机制，（2）通过在每个芯片的最后一个级别缓存中使用两个功能对称的模块来优化性能和成本的构造（D | F-LLLC）和每个内存控制器（D | F-MEM）（D | F-MEM）。这些结构中的每一个都分为两个部分：（2.1）第一个结构由一个小松散包容性的稀疏目录组成，其中只有每个存储器控制器（d-mem）（d-mem）和（2.2）在芯片（d-llc）中跟踪最积极的数据，第二个是一个d-left计数滤波器，其内存的内存或块的内部对内部的群体或内部（chip）的内部范围（或者）内部的内部（floom）的内部差异约为conip，或者是内部内部的（f）。 （F-MEM）。这两种结构的协调工作最大程度地减少了对处理器感知的平均内存潜伏期的相干相关影响。我们的提议能够将类似于高传输的连贯协议的性能提高到25％至60％。
The use of multi-chip modules (MCM) and/or multi-socket boards is the most suitable approach to increase the computation density of servers while keep chip yield attained. This paper introduces a new coherence protocol suitable, in terms of complexity and scalability, for this class of systems. The proposal uses two complementary ideas: (1) A mechanism that dissociates complexity from performance by means of colored-token counting, (2) A construct that optimizes performance and cost by means of two functionally symmetrical modules working in the last level cache of each chip (D|F-LLC) and each memory controller (D|F-MEM). Each of these structures is divided into two parts: (2.1) The first one consists of a small loosely inclusive sparse directory where only the most actively shared data are tracked in the chip (D-LLC) from each memory controller (D-MEM) and, (2.2) The second is a d-left Counting Bloom Filter which stores approximate information about the blocks allocated, either inside the chip (F-LLC) or in the home memory controller (F-MEM). The coordinated work of both structures minimizes the coherence-related effects on the average memory latency perceived by the processor. Our proposal is able to improve on the performance of a HyperTransport-like coherence protocol by from 25%-to-60%.
