Defending Event-Triggered Systems against Out-of-Envelope Environments

2025-12-06

AI Summary

Event-triggered systems suffer from interrupt storms and degraded timeliness/safety when operating beyond their safe envelope—i.e., under unanticipated environmental conditions. To address this, we propose an importance-driven robust scheduling framework. Our approach introduces a novel “task importance” dimension—orthogonal to both priority and criticality—and integrates mixed-criticality principles to jointly model environmental assumptions and regulate interrupt traffic. We formally verify schedulability using rigorous real-time analysis techniques. Experimental evaluation demonstrates that the framework significantly enhances guarantee rates for critical tasks under anomalous workloads, substantially narrowing the robustness gap between event-triggered and time-triggered systems. This work establishes a new paradigm for designing real-time systems resilient to environmental uncertainty.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Intelligent Robots: State Estimation
• Reasoning under Uncertainty: Sequential Decision Making

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements

Abstract

The design of real-time systems is based on assumptions about environmental conditions in which they will operate. We call this their safe operational envelope. Violation of these assumptions, i.e., out-of-envelope environments, can jeopardize timeliness and safety of real-time systems, e.g., by overwhelming them with interrupt storms. A long-lasting debate has been going on over which design paradigm, the time- or event-triggered, is more robust against such behavior. In this work, we investigate the claim that time-triggered systems are immune against out-of-envelope behavior and how event-triggered systems can be constructed to defend against being overwhelmed by interrupt showers. We introduce importance (independently of priority and criticality) as a means to express which tasks should still be scheduled in case environmental design assumptions cease to hold, draw parallels to mixed-criticality scheduling, and demonstrate how event-triggered systems can defend against out-of-envelope behavior.

Problem

• Defends event-triggered systems against interrupt storms in out-of-envelope environments
• Investigates time-triggered immunity and event-triggered defense strategies
• Introduces importance to schedule tasks when environmental assumptions fail

Innovation

• Introduces importance for task scheduling in overload
• Defends event-triggered systems against interrupt storms
• Draws parallels to mixed-criticality scheduling techniques