Skyloft: A General High-Efficient Scheduling Framework in User Space

Abstract

Skyloft is a general and highly efficient user-space scheduling framework. It leverages user-mode interrupt to deliver and process hardware timers directly in user space. This capability enables Skyloft to achieve μs-scale preemption. Skyloft offers a set of scheduling interfaces that supports different scheduling policies, including both preemptive and nonpreemptive ones. Operating as a user-space scheduling framework, Skyloft is compatible with Linux and integrates seamlessly with high-performance I/O frameworks like DPDK.Evaluation results show that optimizations in per-CPU scheduling with user-space timer interrupts allow Skyloft's Completely Fair Scheduler (CFS) and Round Robin (RR) to significantly reduce wake-up latency compared to their Linux counterparts (100μs vs. 10000μs). In comparison to the general scheduling framework ghOSt, Skyloft achieves a 1.2× increase in maximum throughput for Latency Critical (LC) applications. Additionally, unlike the specialized scheduling framework Shinjuku, Skyloft not only supports LC applications but also efficiently allocates CPU resources to Best Effort (BE) applications under low load conditions. By incorporating a 5μs preemption mechanism into the Work-Stealing strategy, a RocksDB Server running on Skyloft exhibits a performance improvement of 1.9× compared to Shenango.