关键词: 多任务调度, 实时性, 高精度定时器, 用户态中断处理

Abstract: Task scheduling in Linux kernel has tremendous overhead, and thus cannot fulfill the requirement of real-time applications. ULight, a real-time multi-task scheduling framework running in Linux user space was proposed to conquer this problem. ULight consists of three core modules: multi-task scheduling module, timer module and user-mode interrupt handling module. The multi-task scheduling module provides priority-based preemptive scheduling in Linux user space to reduce the overhead of task switch and scheduling; the timer module introduces a high-resolution timer system to support time-sharing scheduling, enable task sleep and increase preemption points; the user-mode interrupt handling module builds up an channel between kernel and user space, which enables user-mode threads to handle interrupts directly and efficiently in Linux user space. The experiment results show that, ULight brings much less overhead than Linux Pthread in terms of task scheduling; and keeps the precision of the timer stable within 20 μs; and can response to interrupts rapidly in user space.

Key words: user-mode task scheduling, real-time, high-resolution timer, user-mode interrupt handling