Technical Articles
2025-01-13

Differences and Similarities Between RTOS and Linux

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作者 | strongerHuang
公众号 | strongerHuang
Many embedded developers have such doubts: What is the difference between RTOS and Linux?
RTOS: Real-Time Operating System, refers to an operating system that can accept and process external events or data at a fast enough speed when they occur, and the results of the processing can control the production process or respond quickly to the processing system within a specified time, scheduling all available resources to complete real-time tasks, and controlling all real-time tasks to run in coordination.
Linux, generally refers to GNU/Linux, is a free and freely distributed UNIX-like operating system, whose kernel was first released by Linus Benedict Torvalds on October 5, 1991. It is mainly inspired by Minix and Unix ideas and is a multi-user, multitasking, multi-threading, and multi-CPU operating system based on POSIX.

Differences Between RTOS and Linux

Both RTOS and Linux belong to the embedded field, here are some main differences.

1. Real-time Performance

RTOS: RTOS is an operating system designed specifically for real-time applications, its main feature is the ability to respond to inputs within a predetermined time and complete outputs within a given time to ensure real-time performance. The scheduler and kernel of RTOS are optimized for real-time task processing, allowing them to prioritize tasks within a specific time.

Linux: Linux itself is not a hard real-time operating system, but it can meet a certain degree of real-time requirements through specific configurations and optimizations. However, since Linux needs to handle a large number of system schedules and various other tasks, its real-time performance is relatively poor.

2. Kernel Design

RTOS: The kernel of RTOS is usually very lightweight, allowing only a single application to run on it. This design makes RTOS very popular in resource-constrained embedded systems.

Linux: The Linux kernel is a complete operating system kernel that has gradually developed. It supports multi-user and multitasking processing and provides rich networking capabilities and device independence.

3. Application Scenarios

RTOS: RTOS is mainly used in embedded systems that require high real-time performance, such as IoT devices, industrial control, automotive electronics, etc. In these scenarios, RTOS can ensure that tasks are processed within a predetermined time to meet real-time control requirements.

Linux: Linux is widely used in servers, desktop computers, mobile devices, and other more complex systems. It performs well in scenarios that require multitasking, a rich software ecosystem, and extensive hardware support.

4. Performance and Resource Requirements

RTOS: RTOS typically has higher performance, and devices running RTOS also have advantages in startup and recovery times. This is because RTOS does not need to preprocess a large amount of code and data but directly starts the application. In addition, RTOS has a smaller memory footprint and lower resource requirements, making it suitable for use in resource-limited embedded devices.

Linux: Linux usually requires relatively more system resources, such as memory and processing power. Although Linux can be configured and optimized to adapt to different hardware environments, its performance may not be as good as RTOS in resource-constrained embedded systems.

5. Examples

RTOS Example: An industrial automation system needs to monitor and control various devices on the production line in real-time. Using RTOS can ensure that each device responds and processes within the predetermined time, thus achieving efficient automated production.

Linux Example: A large data center needs to run multiple servers to process a large amount of data and tasks. Using Linux can build a stable, reliable, and easy-to-manage server cluster to meet the needs of the data center.

6. Development and Support

Linux: Linux has a large community and a wide range of application development tools, providing developers with rich resources and support. In addition, the open-source nature of Linux allows its code to be freely modified and customized to meet specific needs.

RTOS: RTOS is mainly aimed at real-time embedded applications, so its development tools and community may be relatively small. However, RTOS products targeted at specific fields (such as FreeRTOS, VxWorks, etc.) often have professional technical support and rich documentation to help developers quickly realize applications.

Similarities in Application Scenarios

Although RTOS and Linux have different main characteristics and advantages, they still have similarities in certain application scenarios.

1. Embedded Systems
RTOS: RTOS is widely used in embedded systems, especially in resource-constrained and high real-time environments.
Linux: Although Linux is not designed specifically for embedded systems, it also has many applications in embedded systems, especially in cases where more powerful functions and software ecosystems are required. For example, some high-end embedded devices or devices requiring complex networking functions may choose Linux.
2. Internet of Things (IoT)
RTOS: In IoT devices, RTOS is popular due to its high real-time performance and low resource consumption. These devices often need to respond quickly to external events, and due to cost and energy constraints, they require efficient operating systems.
Linux: Linux is also widely used in the IoT field. Especially for IoT devices that require more complex networking functions, data processing capabilities, or software ecosystems, Linux may be a better choice.
3. Industrial Automation
RTOS: In industrial control systems, the high real-time performance and stability of RTOS make it an ideal choice for critical applications. For example, in systems that require precise control of production processes or devices, RTOS can ensure that tasks are processed within the predetermined time.
Linux: Although Linux may not be as real-time as RTOS, it also has applications in industrial automation. For example, Linux can be used to build industrial-grade servers or data processing centers to support complex industrial networks or data processing needs.
4. Network Devices
RTOS: In network devices, RTOS can be used to implement efficient data processing and network communication mechanisms. For example, in routers, switches, or firewalls, RTOS can ensure that data packets are processed within the predetermined time to meet network performance requirements.
Linux: Linux is also widely used in network devices. Due to its powerful networking capabilities and flexible programming interfaces, Linux has become the operating system of choice for many network device manufacturers.
5. Open Source and Customizability
RTOS: Although RTOS products may not have as extensive an open-source community as Linux, many RTOS also offer customization and extension capabilities. Users can customize the functions and performance of RTOS according to their needs.
Linux: The open-source nature of Linux allows users to freely modify, customize, and extend the operating system. This provides developers with great flexibility to meet various specific application needs.

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Differences and Similarities Between RTOS and Linux

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