PREEMPT_RT Linux Real-Time: Threaded Interrupts to Microsecond Latency

Introduction

General-purpose Linux kernel prioritizes throughput over deterministic latency. PREEMPT_RT transforms Linux into a hard real-time system with worst-case scheduling latency reduced from milliseconds to microseconds.

Core Mechanisms

Threaded interrupts move ISR execution into kernel threads that can be preempted by higher priority tasks. spinlock becomes rt_mutex with priority inheritance. High-resolution timers (hrtimer) provide nanosecond precision.

Performance

Typical Max latency: Generic kernel >1000