Real-Time Linux: How Far Can It Go?  | Deciphering Mechanisms and Performance Comparisons – Key Criteria for Choosing Between Real-Time Linux and Commercial Real-Time OSes

As systems grow in scale and complexity, Linux-based approaches are attracting attention even in mission-critical systems in recent years. While Linux offers a rich ecosystem and flexible extensibility, being open-source raises the question of how much real-time performance it can guarantee when compared to commercial real-time OSes.

This document focuses on "PREEMPT_RT," a patch that improves Linux's real-time performance, and explains in detail the criteria for choosing between Linux and commercial real-time OSes in mission-critical systems, covering the following topics:

Contents of This Document

• What is "mission-critical" in embedded systems?
• Example requirements for mission-critical systems
• Revisiting real-time performance and real-time OSes
• Linux's approaches to real-time performance
• PREEMPT_RT and what preemption means
• PREEMPT_RT key elements (interrupt handler threadification, lock API implementation conversion, real-time RCU)
• PREEMPT_RT performance analysis (jitter evaluation, throughput evaluation)
• PREEMPT_RT vs. commercial real-time OS comparison table
• Solutions supporting real-time system development