On the Joint Optimization of Function Assignment and Communication Scheduling toward Performance Efficient Serverless Edge Computing

Serverless edge computing is booming as an efficient carrier of deploying complex applications composed of dependent functions, whose assignment decisions highly influence the application performance. Although similar problem has been widely studied, none of existing approaches considers the diversity of communication styles, which is specially introduced in serverless computing and also imposes high influence to the performance efficiency. We compare two communication styles, called direct-passing and remote-storage, to transmit intermediate data between functions. We find that there is no single communication style that can prevail under all scenarios and the optimal selection depends on several factors, such as fanout degree, data size, and network bandwidth. Hence, how to select the appropriate communication style for each inter-function communication link, together with the function assignment decision, is essential to the application performance. To this end, we propose a Priority-based ASsignment and Selection (PASS) algorithm with joint consideration of function assignment and communication style selection. We theoretically analyze the approximation ratio of PASS algorithm and extensive experiments on real-world applications show that PASS can averagely reduce the completion time by 24.1% in comparison with state-of-the-art approaches.