To improve the application-level data efficiency, the scheduling of coflows, defined as a collection of parallel flows sharing the same objective, is prevailing in recent data centers. Meanwhile, optical circuit switches (OCS) are gradually applied to provide high data rate with low power consumption. However, so far few research outputs have covered the flow, let alone the coflow, scheduling in the context of OCS. In this work, we investigate coflow scheduling in OCS-based data centers. We first derive a novel operation called regularization processed respectively on the flow traffic demands and the flow start times, which can be efficiently implemented and reduce the circuit reconfiguration frequency dramatically. We then propose a 2-approximation algorithm, called Reco-Sin , for single coflow scheduling to minimize the coflow completion time (CCT). For multiple coflows, we derive Reco-Mul to minimize the total weighted CCT, which can transform any non-preemptive multi-coflow scheduling in packet switches to a scheduling scheme in OCS. Reco-Mul can achieve a constant approximation under the assumption that no tiny flows will be transmitted in OCS. To get rid of this assumption, we present another multiple coflow scheduling scheme, named Reco-Mul+ , which has an approximation ratio of $O(K)$ . Here, $K$ is the total number of coflows. Extensive simulations based on Facebook data traces show that our approaches outperform state-of-the-art schemes significantly, i.e., one single coflow can be finished up to $1.97\times $ faster with Reco-Sin , and multiple coflows can be completed up to more than $2\times $ faster with Reco-Mul and Reco-Mul+ .

中文翻译：

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光电路交换机中基于正则化的协流调度

为了提高应用层的数据效率，coflow的调度，定义为共享同一目标的并行流的集合，在最近的数据中心盛行。同时，光电路开关（OCS）逐渐被应用以提供高数据速率和低功耗。然而，到目前为止，很少有研究成果涵盖了 OCS 上下文中的流程，更不用说协流了。在这项工作中，我们研究了基于 OCS 的数据中心的协流调度。我们首先推导出一个新的操作叫做正则化分别对流量需求和流量开始时间进行处理，可以有效地实现并显着降低电路重构频率。然后我们提出了一种 2-近似算法，称为再罪 , 用于单个 coflow 调度以最小化 coflow 完成时间 (CCT)。对于多个协流，我们推导出Reco-Mul 最小化总加权 CCT，这可以将分组交换机中的任何非抢占式多协流调度转换为 OCS 中的调度方案。 Reco-Mul在 OCS 中不会传输微小流的假设下，可以实现常数近似。为了摆脱这个假设，我们提出了另一个多协流调度方案，命名为Reco-Mul+ ，其近似比为 $O(K)$ . 这里， $K$ 是协流的总数。基于广泛的模拟Facebook 数据跟踪表明，我们的方法明显优于最先进的方案，即一个单一的 coflow 可以完成 $1.97\times $ 更快 再罪 , 并且最多可以完成多个 coflows $2\times $ 更快 Reco-Mul 和 Reco-Mul+ .