The decision between RTOS and Linux is far from clear-cut. Especially when it comes to development costs.
RTOS vs Linux: a prime example
When one of our clients approached us to design a router with data logger functionality for an energy management system, they felt uncertain. Linux provides quicker development time and lower initial costs; however, production expenses will be higher.
In this instance, the decision was straightforward. Given the project’s complex functionality and high-performance requirements, we recommended using Linux because of its ability to handle demanding workloads.
“Yet, in some cases, selecting the most suitable approach can be quite challenging. Certain embedded system projects, such as software for human-machine interface devices, pose unique challenges that make the best choice unclear,” says Pavlo Matiieshyn, Head of Embedded Development at Lemberg Solutions.
Typically, a client and a team of embedded developers evaluate several critical factors to reach a final decision.
Key drivers behind the RTOS vs Linux choice
The key factors influencing the decision include the complexity of developing business logic, development costs, and performance. Let’s take a closer look at the entire list of factors.
Business logic
“Choosing between Linux and RTOS depends on the purposes a client sets for their system,” shares Ivan Kubara, the Embedded Team Lead.
For a simple user interface with few buttons, a real-time operating system may be sufficient. However, if a product’s user interface includes menus, transitions, and network connectivity, Linux becomes a more effective choice.
To get a better insight into the system choice, let’s take a look at another case — a smart home controller with a graphical display, Wi-Fi, and GSM connectivity. Using Linux, an embedded development team can quickly start building business logic and focus on functionality. In contrast, when using an RTOS, specialists must first configure the project, connect and test drivers, and manage inputs from various sources. In simple, too many low-level steps before even starting the core logic.
For embedded system projects, such as an IoT telemedicine platform for cough sound recognition, Linux is a better option. In this instance, LS specialists created an SBC-based IoT gateway device with secure embedded software that monitors patients and helps to deliver health-related data to caregivers.
Integration
The complexity of integration on RTOS can be illustrated by this quote: “Our team spent over a month resolving driver issues, even with the manufacturer’s support.” This is how Pavlo Matiieshyn recollects selecting a specific integrated circuit for the client’s battery management system. On Linux, drivers are generally better tested and more widely used, reducing the effort needed to work on low-level functionality.
While both Linux and RTOS offer pre-built drivers and resources, using the latter can be time-consuming in scenarios like the one mentioned above. For the development team, this means they must invest more effort and time to ensure RTOS functions correctly. In contrast, ready-made drivers for Linux function well without major adjustments.
Scalability
Linux is a suitable choice for developing embedded systems that involve data processing, complex user interfaces, routers, diverse data streams, and computer vision. In essence, all scenarios where development complexity and scalability needs outweigh the cost of the device.
Take, for instance, a charging station. Developing software on Linux will offer greater functionality compared to RTOS; moreover, achieving the same result will require several subsystems operating on a real-time operating system.
Another illustration is running an IoT modem with six CAN lines — a complex task requiring significant computational power and software optimization to prevent overload. We opted for an MCU in this case, but it took considerable time to optimize performance and properly configure the RTOS. This process would have been much smoother on Linux. However, for projects like an IoT telemetry solution for Voltfang's energy storage systems, RTOS is a better fit.
Performance
For tasks demanding high performance and heavy workloads, Embedded Linux development stands out as the best option.
And our embedded software development for 3D bioprinters project confirms it. In this case, the embedded team worked on continuous improvement of the client’s Qt apps, middleware, and firmware. To enhance the functionality of the devices, LS engineers modified Embedded Linux applications and developed new features for them.
Cybersecurity
“Responsibility for cybersecurity is always on the embedded development team for both Linux and RTOS,” shares Ivan Kubara. In an RTOS, the system is more optimized, which lowers vulnerabilities; in contrast, a Linux system’s greater complexity may lead to increased security risks.
Development time
The difference between development time on RTOS vs Linux becomes apparent when looking at a typical task. For a device with multiple communication interfaces and a display, where data must be collected and processed, Linux generally requires less time to implement.
Take, for instance, complex applications such as the PoC development of a sports tech fitness device. An embedded development team benefited from using Linux since many resources were instantly available, simplifying the software development process.
Support & maintenance
Updating Linux compared to RTOS might require more involvement from a development team.
“Whenever a driver or system component is updated, it is essential to verify compatibility across various Linux layers. This creates dependencies that can slow down the update process, leading to delays and added costs,” shares Ivan Kubara, the Embedded Team Lead.
In contrast, RTOS drivers are custom-built for specific hardware and rarely change. However, as more features are added, it becomes increasingly difficult to maintain RTOS.
Development costs
Comparing RTOS vs Linux in the context of development costs is anything but black and white.
Pavlo Matiieshyn states, “for clients, the primary concern often revolves around the hardware costs.” RTOS may be more cost-effective for mass production. However, Linux allows for faster deployment and reduces development costs, making it an ideal choice for businesses looking to launch products rapidly.
The table below shows how key cost factors could impact the development costs of a basic function: LED flashing in response to system activity or status changes.
Final thoughts
Choosing RTOS vs Linux for an embedded system development depends primarily on its complexity and purpose.
A real-time operating system may be more cost-effective for mass production and require less upgrading effort. However, if the embedded systems project is multi-faceted, RTOS might not be a good choice for extensive business logic requirements, integration, and high performance.
Linux allows for faster deployment and reduces software development costs. It is an ideal choice for projects requiring complex business logic, high performance, and increased scalability. However, upgrading Linux systems can be more challenging, and the overall platform cost may be higher.
