Rack-scale computing systems are promising to undertake the emerging large-scale applications by distributing massive tasks to processing cores. The communication and coordination efficiency of these tasks and resources directly affect the system performance and energy consumption. Silicon photonic interconnects are expected to address the communication and system power consumption challenges imposed on rack-scale systems. However, the control for optical interconnects can cause server performance degradation if not properly designed, especially for the complicated and time-consuming multidomain networks. In this paper, we study the optical interconnects for rack-scale computing systems and propose a new communication flow and control scheme for the efficient coordination of distributed resources. Particularly, we first propose a forward propagation strategy that parallels the path reservation process with the distributed tasks connection setup. Second, we develop a pre-emptive chain feedback (PCF) scheme to optimize multidomain path reservation. The PCF scheme pre-emptively allocates network resources with the help of multicell reservation window and quickly releases resources with a feedback mechanism. This solution increases the network resources utilization and task coordination efficiency while minimizing path reservation overheads. Comparing to the baseline InfiniBand network fabric and handshake scheme, PCF can improve network throughput greatly under uniform and hotspot traffic patterns. Realistic benchmark results show that the PCF scheme on average reduces 52% and 60% energy consumption per unit system performance than InfiniBand and the handshake scheme for a 256-node rack system.

中文翻译：

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用于节能机架级计算系统的多域芯片间/芯片内硅光子网络

机架级计算系统有望通过将大量任务分配给处理核心来承担新兴的大规模应用程序。这些任务和资源的通信和协调效率直接影响系统性能和能耗。硅光子互连有望解决机架规模系统所面临的通信和系统功耗挑战。但是，如果设计不当，对光互连的控制会导致服务器性能下降，特别是对于复杂且耗时的多域网络。在本文中，我们研究了机架规模计算系统的光互连，并提出了一种新的通信流和控制方案，以有效协调分布式资源。特别，我们首先提出了一种前向传播策略，该策略将路径保留过程与分布式任务连接设置并行。其次，我们开发了一种先发制人的链反馈（PCF）方案来优化多域路径预留。PCF方案借助多小区预留窗口抢占网络资源，通过反馈机制快速释放资源。该解决方案提高了网络资源利用率和任务协调效率，同时最大限度地减少了路径预留开销。与基准 InfiniBand 网络结构和握手方案相比，PCF 可以在均匀和热点流量模式下大大提高网络吞吐量。