20 years later, real-time Linux makes it to the kernel
The work done on real-time Linux has benefitted the open-source OS for years, but it was only this week that Linus Torvalds admitted its last piece into the mainline kernel. Exactly what took so long?
After 20 years, Real-Time Linux (PREEMPT_RT) is finally -- finally -- in the mainline kernel. Linus Torvalds blessed the code while he was at Open Source Summit Europe. Why is this a big deal? Let's start by explaining what a real-time operating system (RTOS) is and what it's good for.
What is an RTOS?
An RTOS is a specialized operating system designed to handle time-critical tasks with precision and reliability. Unlike general-purpose operating systems like Windows or macOS, an RTOS is built to respond to events and process data within strict time constraints, often measured in milliseconds or microseconds. As Steven Rostedt, a prominent real-time Linux developer and Google engineer, put it, "Real-time is the fastest worst-case scenario."
He means that the essential characteristic of an RTOS is its deterministic behavior. An RTOS guarantees that critical tasks will be completed within specified deadlines. Many people assume that RTOSs are for fast processes. They're not. Speed is not the point in RTOSs -- reliability is. This predictability is crucial in applications where timing is essential, such as industrial control systems, medical devices, and aerospace equipment.
One example of real-time operating systems in use today is VxWorks, which is used in NASA's Mars rovers to guide them, and in the Boeing 787 Dreamliner aircraft to control avionics systems, ensuring real-time responsiveness for flight controls. Another example is QNX Neutrino, which is widely used in cars for infotainment, and advanced driver-assistance systems such as anti-lock brakes.
One example of real-time operating systems in use today is VxWorks, which is used in NASA's Mars rovers to guide them, and in the Boeing 787 Dreamliner aircraft to control avionics systems, ensuring real-time responsiveness for flight controls. Another example is QNX Neutrino, which is widely used in cars for infotainment, and advanced driver-assistance systems such as anti-lock brakes.
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