Datacenter applications desire low latency for short messages to provide a better user experience. Therefore, one of the goals of datacenter networks is to minimize flow completion time (FCT), especially for short flows. Multiple scheduling disciplines have been proposed to achieve this goal. In this paper, we develop a Dynamic Longer Stay Less Priority (D-LSLP) which looks at the current queue occupancy to adjust the demotion threshold for the packets of the flows arriving in the strict priority queues. Initially, D-LSLP considers every flow to be a short flow, and with the passage of time, the flow is demoted to the lower priority queue, similar to Multilevel Feedback Queue (MLFQ) Scheduling. It enables short flows to be completed in a couple of higher-priority queues. In contrast, large flows are demoted to the lower priority queues after remaining active in the queues for a certain amount of time (demotion threshold). However, for the different traffic patterns with different distribution of flow lengths, the demotion threshold for the flows should be adapted automatically. In this paper, we leverage the programmable nature of the P4 switches to measure the instant queue occupancy in the P4, which can be used to adjust the demotion threshold accordingly for the highest priority queue. This enables D-LSLP to increase or decrease its highest priority demotion threshold based on the instant queue status. D-LSLP allows multiple traffic patterns to coexist without manually tuning the demotion thresholds. Furthermore, it reduces the tail drop in the highest priority queue when many short flows overwhelm the highest priority queue. The performance evaluation shows that it works equally well for different traffic patterns without operator intervention.

中文翻译：

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用于数据中心网络中自动流量调度的即时队列占用

数据中心应用程序希望短消息具有低延迟，以提供更好的用户体验。因此，数据中心网络的目标之一是最小化流完成时间（FCT），特别是对于短流。为了实现这一目标，已经提出了多种调度规则。在本文中，我们开发了动态较长停留较少优先级（D-LSLP），它查看当前队列占用率，以调整到达严格优先级队列的流数据包的降级阈值。最初，D-LSLP将每个流视为短流，随着时间的推移，该流被降级到较低优先级队列，类似于多级反馈队列（MLFQ）调度。它允许在几个优先级较高的队列中完成短流。相反，大流在队列中保持活动状态一定时间（降级阈值）后会被降级到较低优先级队列。然而，对于具有不同流长度分布的不同业务模式，应该自动调整流的降级阈值。在本文中，我们利用 P4 交换机的可编程特性来测量 P4 中的即时队列占用率，这可用于相应地调整最高优先级队列的降级阈值。这使得 D-LSLP 能够根据即时队列状态增加或减少其最高优先级降级阈值。 D-LSLP 允许多种流量模式共存，无需手动调整降级阈值。此外，当许多短流淹没最高优先级队列时，它减少了最高优先级队列中的尾部丢弃。性能评估表明，它对于不同的流量模式同样有效，无需操作员干预。