What Is a Real-Time Operating System, and Who Needs One?

With such cutting-edge technology as autonomous vehicles and medical IoT devices, real-time performance is becoming a necessity — thus, the increasing need for real-time operating systems.

Christopher Tozzi, Technology analyst

March 5, 2024

6 Min Read
empty cockpit of autonomous car

Compared with other niches within the IT industry, operating systems may not seem especially exciting. The same OS platforms — Windows, Linux, and macOS — have dominated for decades. OS architectures and features evolve more slowly and are much less trendy than, say, cloud-native application design or generative AI.

Yet, there is one aspect of OS design that could turn into a cutting-edge feature for some use cases: real-time operating system (RTOS) capabilities. Although real-time OS platforms are not new, real-time operating systems may become increasingly important in areas such as edge computing and the internet of things (IoT).

Keep reading for a look at what real-time operating systems are and why they may become one of the next big things (or, at least, something you'll hear more about in coming years) in the world of tech.

What Is a Real-Time Operating System?

A real-time operating system is one capable of guaranteeing that certain tasks will be performed in as close to real time as possible.

If that sounds confusing, it might be because standard operating systems typically appear to operate in real time. Usually, if you tell a computer to start an application or copy a file, for example, it will do it right away. The process may take time to complete, but the OS response to your request appears to happen immediately.

Related:The Future of Windows: Windows 11 Leans Into Hybrid Future

In reality, though, there is always some delay between when you ask a computer to do something and when it actually starts to do it. The delays are often imperceptible to humans, but they exist nonetheless — and they can become more noticeable when a machine is under heavy load or receives many requests at once. If you have a hundred browser tabs open, for instance, you may notice a delay when you add another one, because it takes your computer time to switch away from the tasks running in the existing tabs and start the task of opening a new tab.

Real-time operating systems provide the ability to prioritize certain requests such that the computer begins handling them right away. Thus, instead of waiting for your computer to get around to opening a new browser tab on top of the hundred you already have running, a real-time operating system would allow you to tell the OS that opening a new tab is a top priority and to react to the request as quickly as possible.

It's important to note that real-time operating systems don't actually perform tasks in true real time. As with standard OSes, there will always be some delay between when a user makes a request and when the computer responds. Thus, the term real-time OS is something of a misnomer. However, the key difference between a real-time OS and a conventional OS is that a real-time OS is able to prioritize certain tasks so that delays are minimal.

Related:What Is Linux? An Operating System, Software, Program, and More

How Do Real-Time Operating Systems Work?

There are different approaches to implementing real-time operating systems. But in general, an RTOS works by providing a special task scheduling system that allows users or applications to assign priority levels to tasks. When a task with a high priority is introduced, the RTOS recognizes it and begins responding to it immediately.

In contrast, the schedulers of traditional operating systems usually try to balance all requests equally, allocating resources in a way designed to guarantee the best overall performance across all tasks and processes. A real-time OS is different because it can prioritize certain tasks over others.


Benefits and Use Cases for Real-Time Operating Systems

The main benefit of a real-time OS is simple: It reacts to certain events or requests as quickly as possible.

In conventional computing scenarios, this ability is typically not very important. If you're hosting a web app, for example, you probably don't have a reason to tell your operating system to prioritize certain processes over others. On the contrary, you want the OS to manage requests in a way that maximizes overall stability and performance across all tasks and processes.

But for other use cases, real-time operating systems can be valuable. Consider the following examples:

  • Autonomous vehicles, which may need their computers to prioritize certain requests — such as deployment of brakes or airbags if the vehicle suddenly appears headed for a crash.

  • Medical internet of things devices like smart pacemakers, which must prioritize requests to adjust a patient's target heart rate if they detect a sudden change that requires remediation.

  • Manufacturing processes, where the ability to guarantee that certain tasks take place in a defined order can be critical.

These are all examples of use cases where fine-grained control over the timing of events is critical — sometimes even from a life-and-death perspective. Traditional operating systems can't provide that control, but real-time OSes can.

Where Can You Get a Real-Time OS?

In most cases, deploying a real-time operating system doesn't require adopting an entirely new OS. You just need a real-time version of the OS you already use.

For example, for Linux-based operating systems, you can swap out your standard Linux kernel for a real-time kernel. Most of the major Linux vendors — such as Red Hat and Canonical — offer official real-time variants of their distributions. You can also implement a real-time kernel yourself using the PREMPT_RT patch, which you can install on any Linux kernel.

Real-time options are also available for Windows, although Microsoft has not invested extensively in this area — probably because Windows is not widely used for the types of use cases that require an RTOS.


Real-time operating systems won't replace traditional operating systems wholesale because most computing use cases don't require an RTOS. But for certain types of applications — like those that power self-driving cars or manufacturing processes — real-time operating systems offer benefits that just aren't available from a standard OS. Expect to hear more about real-time OSes in the coming years as businesses look for ways to take greater advantage of edge computing, the IoT, and other use cases where real-time performance is a priority.

About the Author(s)

Christopher Tozzi

Technology analyst, Fixate.IO

Christopher Tozzi is a technology analyst with subject matter expertise in cloud computing, application development, open source software, virtualization, containers and more. He also lectures at a major university in the Albany, New York, area. His book, “For Fun and Profit: A History of the Free and Open Source Software Revolution,” was published by MIT Press.

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