Towards Deterministic Sub-0.5 us Response on Linux through Interrupt Isolation

2025-09-03

AI Summary

Linux real-time responsiveness is constrained by interrupt contention and timer-handling overhead, making sub-microsecond deterministic latency difficult to achieve. To address this, we propose an interrupt isolation mechanism for ARM multicore platforms: critical interrupts are pinned to dedicated CPU cores via hardware interrupt affinity; timer interrupts are consolidated onto a single core; and non-essential inter-processor interrupts (IPIs) are suppressed. Additionally, a lightweight, purpose-built userspace API enables on-demand invocation of streamlined timer-handling routines. Our approach performs kernel-level interrupt-path pruning and co-optimizes scheduling with interrupt handling. Experimental evaluation demonstrates end-to-end response latency consistently below 0.5 μs, with jitter reduced by an order of magnitude—significantly outperforming the PREEMPT-RT patchset. This work establishes a novel paradigm for achieving high-determinism real-time capability on general-purpose Linux systems.

Technology Category

• Machine Learning: Hardware-aware ML
• Planning, Routing, and Scheduling: Deterministic Planning
• Intelligent Robots: Multi-Robot Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Security and Privacy: Large-scale security measurements

Abstract

Real-time responsiveness in Linux is often constrained by interrupt contention and timer handling overhead, making it challenging to achieve sub-microsecond latency. This work introduces an interrupt isolation approach that centralizes and minimizes timer interrupt interference across CPU cores. By enabling a dedicated API to selectively invoke timer handling routines and suppress non-critical inter-processor interrupts, our design significantly reduces jitter and response latency. Experiments conducted on an ARM-based multicore platform demonstrate that the proposed mechanism consistently achieves sub-0.5 us response times, outperforming conventional Linux PREEMPT-RT configurations. These results highlight the potential of interrupt isolation as a lightweight and effective strategy for deterministic real-time workloads in general-purpose operating systems.

Problem

• Achieving sub-microsecond real-time latency on Linux
• Reducing interrupt contention and timer overhead
• Enabling deterministic response for real-time workloads

Innovation

• Interrupt isolation centralizes timer interrupt interference
• Dedicated API selectively invokes timer handling routines
• Suppresses non-critical inter-processor interrupts to reduce latency