FaaSPR: Latency-Oriented Placement and Routing Optimization for Serverless Workflow Processing

Workflow processing enhances the applicability of serverless computing while retaining the characteristics of fine-grained resource management and elastic scalability. However, current serverless platforms lack targeted optimization of placement and routing strategies for workflow processing, leading to high overheads due to inter-server data transmission, instance cold starts, and function request queuing. We propose FaaSPR, a serverless scheduling system that exploits placement and routing optimizations to minimize workflow processing latency. FaaSPR groups instances with potential data transmission and proportionally distributes groups with heterogeneous instances across multiple servers, taking into account resource constraints and historical placement traces. This method addresses the issues of poor scalability and frequent instance migrations in existing solutions. Utilizing a routing algorithm based on multi-stage linear programming, FaaSPR minimizes cross-server data transmission within and between instance groups while ensuring load balancing among instances. Experiments show that, compared to the state-of-the-art solution FaaSFlow, FaaSPR decreases the average and 99th percentile tail latency by up to 68.03% and 93.46%, respectively. Additionally, reducing workflow processing latency leads to up to 46.18% decrease in resource consumption for FaaS users.