Difference between Preemptive and Non-Preemptive Kernel

An OS serves as a bridge between hardware resources and user programs. It handles various critical OS tasks. Some examples of the OS are process scheduling, file handling, data protection, and memory management. Furthermore, the kernel is the core of an OS. There are two kinds of OS kernels: preemptive kernels and non-preemptive kernels.

In this article, you will learn about the difference between Preemptive and Non-preemptive Kernel. But before discussing the differences, you must know about Preemptive and Non-preemptive kernels.

What is a Preemptive Kernel?

A computer system has two operation modes: user mode and kernel mode. Kernel mode has more privileges than user mode. Programs running in user mode are not permitted to access memory or hardware resources directly, but kernel-mode programs are permitted to do so.

The preemptive kernel enables you to interrupt a program while it is running. In other terms, the kernel can halt the execution of the presently operating process and enable another process to run. As the name implies, a preemptive kernel is a form of the kernel that always runs the highest priority tasks that are available to execute. Non-reentrant functions may not be used unless and until functions are mutually exclusive. This type of kernel is more secure since it doesn't enable the CPU to continuously run a process for an extended period of time.

What is a Non-Preemptive Kernel?

The non-preemptive kernel doesn't enable interrupting the currently executing process. The execution of a running process cannot be stopped; it will keep running until it exits kernel mode or is blocked. Furthermore, with the non-preemptive kernel, only one process is active at any particular time. As a result, this kernel doesn't arise a race condition on the kernel data structures. Non-preemptive kernels are not as responsive as preemptive kernels when a process runs for a lengthy time.

Key differences between Preemptive and Non-Preemptive Kernel

Here, you will learn about the various key differences between Preemptive Kernel and Non-Preemptive Kernel. Some main differences between Preemptive Kernel and Non-Preemptive Kernel are as follows:

1. A preemptive kernel is a kernel form that permits a process to be replaced when it is in kernel mode. On the other hand, Non-preemptive kernels enable a process executing in kernel mode to be preempted.
2. Some instances of the preemptive kernel are IRIX, Linux, and Solaris OS. In contrast, some instances of the non-preemptive kernel are Windows XP and 2000.
3. Preemptive kernels are complex to design. In contrast, non-preemptive kernels are simpler to design.
4. In a preemptive kernel, the response time is more responsive and deterministic. In contrast, the response time is nondeterministic and less responsive in the non-preemptive kernel.
5. Preemptive kernels are more reliable and useful in practical situations. On the other hand, Non-preemptive kernels offer less security and are less practical.

Head-to-head comparison between Preemptive Kernel and Non-Preemptive Kernel

Here, you will learn about the head-to-head comparison between Preemptive and Non-Preemptive Kernels. Some main differences between Preemptive and Non-Preemptive Kernels are as follows:

Conclusion

In summary, the major difference between a preemptive and non-preemptive kernel is that a preemptive kernel permits a process in kernel mode execution to be interrupted by another process, but a non-preemptive kernel doesn't. Non-preemptive kernels are also simpler to construct. In contrast, preemptive kernels are secure and effective in real-world cases.