Mixed-Criticality Scheduling with I/O

TL;DR

This paper presents an extended mixed-criticality scheduling approach that integrates I/O management, improving task set schedulability in real-time systems with aperiodic I/O requests.

Contribution

It introduces a novel scheduling method combining mixed-criticality tasks with I/O handling on the same core, surpassing traditional I/O management techniques.

Findings

Enhanced schedulability of task sets with I/O requests

Superior performance over traditional Sporadic Server methods

Effective integration of I/O and mixed-criticality scheduling

Abstract

This paper addresses the problem of scheduling tasks with different criticality levels in the presence of I/O requests. In mixed-criticality scheduling, higher criticality tasks are given precedence over those of lower criticality when it is impossible to guarantee the schedulability of all tasks. While mixed-criticality scheduling has gained attention in recent years, most approaches typically assume a periodic task model. This assumption does not always hold in practice, especially for real-time and embedded systems that perform I/O. For example, many tasks block on I/O requests until devices signal their completion via interrupts; both the arrival of interrupts and the waking of blocked tasks can be aperiodic. In our prior work, we developed a scheduling technique in the Quest real-time operating system, which integrates the time-budgeted management of I/O operations with Sporadic Server scheduling of tasks. This paper extends our previous scheduling approach with support for mixed-criticality tasks and I/O requests on the same processing core. Results show the effective schedulability of different task sets in the presence of I/O requests is superior in our approach compared to traditional methods that manage I/O using techniques such as Sporadic Servers.