Is Linux a Real Time Operating System

Most of the telecommunication and data-communication products use Real Time  Operating   Systems  (RTOS). Application of a RTOS is called embedded software. Let's discuss some basic definitions and classification of RTOS and how Linux does it.

Since  Linux  is an open-source  operating   system  with strong ability to support multiple processors, including MIPS, x86, PowerPC, its becoming more popular with the embedded software developers as RTOS. Because of Linux open-source nature, its constantly evolving. In this article, the standard Linux is analyzed.

What's an RTOS

An RTOS has ability to respond to an external event within a deterministic time. The performance of the real time is measured by the RTOS customers based on the information provided by the RTOS vendors to analyze the execution times for interrupts and any system tasks that are higher priority than the customer's tasks.

The "kernel" of a RTOS provides an "abstraction layer" that hides the hardware details of the processor (or set of processors) from application software upon which it runs.

Hard  real-time applications have a very specific deadline. That is the RTOS must respond to application within a specific time, otherwise an unacceptable result occurs. Something blows up, something crashes, some operation fails, someone dies. Soft real-time applications usually must satisfy a deadline, but if a certain number of deadlines are missed by just a little bit, the  system  may still be considered to be  operating  acceptably.

The Real Time kernel service includes: Task Scheduling, Intertask communication and synchronization, Timer, Dynamic Memory Allocation, and Device I/O Supervisor.Even though Linux kernel provides all these services, in general, Linux is designed for performance-limited applications, but it is not well designed for deterministic response.