Collaborative edge computing has become a popular paradigm where edge devices collaborate by sharing resources. Data dissemination is a fundamental problem in CEC to decide what data is transmitted from which device and how. Existing works on data dissemination have not focused on coflow scheduling in CEC, which involves deciding the order of flows within and across coflows at network links. Coflow implies a set of parallel flows with a shared objective. The existing works on coflow scheduling in data centers usually assume a non-blocking switch and do not consider congestion at different links in the multi-hop path in CEC, leading to increased coflow completion time (CCT). Furthermore, existing works do not consider multiple flow sources that cannot be ignored, as data can have duplicate copies at different edge devices. This work formulates the multi-source coflow scheduling problem in CEC, which includes jointly deciding the source and flow ordering for multiple coflows to minimize the sum of CCT. This problem is shown to be NP-hard and challenging as each flow can have multiple dependent conflicts at multiple links. We propose a source and coflow-aware search and adjust (SCASA) heuristic that first provides an initial solution considering the coflow characteristics. SCASA further improves the initial solution using the source search and adjust heuristic by leveraging the knowledge of both coflows and network congestion at links. Evaluation done using simulation experiments shows that SCASA leads to up to 83% reduction in the sum of CCT compared to benchmarks without a joint solution.

翻译：协作边缘计算已成为一种流行范式，其中边缘设备通过共享资源进行协作。数据传播是CEC中的一个基本问题，旨在决定从哪个设备传输何种数据以及如何传输。现有关于数据传播的研究尚未关注CEC中的协同流调度，该问题涉及决定网络链路上协同流内部及跨协同流的流顺序。协同流指具有共同目标的一组并行流。现有数据中心协同流调度研究通常假设非阻塞交换机，未考虑CEC多跳路径中不同链路的拥塞，导致协同流完成时间增加。此外，现有研究未考虑不可忽略的多流源问题，因为数据在不同边缘设备上可能存在重复副本。本研究构建了CEC中的多源协同流调度问题，该问题需要联合决定多个协同流的源和流顺序以最小化CCT总和。该问题被证明是NP难问题且具有挑战性，因为每个流可能在多个链路上存在多重依赖冲突。我们提出一种源与协同流感知的搜索调整启发式算法，该算法首先基于协同流特性提供初始解，进而利用协同流和链路网络拥塞知识，通过源搜索调整启发式优化初始解。仿真实验评估表明，相较于无联合解决方案的基准方法，SCASA能将CCT总和降低达83%。