What is Linux Kernel? [A Complete Overview]

Q: What kernel property makes it popular?

Open-source properties of a Linux Kernel mainly make it popular because its free modification increases flexibility, versatility, and customizability. It is the property due to its increased number of features.

Q: How is Linux so stable despite using a monolithic kernel?

Due to a mature codebase and robust development model, Linux is very stable despite using a monolithic kernel. As you know the microkernel is so stable and if a failure occurs in one part, it won't hamper the rest of the system. Failure mainly occurs because of the poor kernel code which is not the case for Linux. And for that reason, it is the most stable OS despite having a monolithic kernel.

Q: How can one enhance Kernel performance?

One can enhance or optimize the kernel performance by tuning the system scheduler. The scheduler interacts with the hardware, especially the CPU. So for proper utilization of the CPU, one can do the processes by tuning the scheduler. Another approach can be the increase the virtual memory by swapping memory from the hard disk.

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Linux Kernel is the lowest-level software at the heart of the Linux Operating system that connects the underlying components and utilities. It is called the interface of the hardware and the interface of all the applications. Kernel directly interacts with the hardware and hides all its complexity.

Table of Contents Expand

Let’s see the Linux kernel in detail in this article.

Kernel Type of Linux

Linux has a monolithic kernel which means all the functions and services run for the same kernel address. For this property, it has enhanced the performance and efficient communication between components. In a monolithic kernel, if problems happen in one part then it affects the entire system which causes instability. But despite having a monolithic kernel, Linux is the most stable operating system because of its strong and well-defined kernel code.

Linux Kernel Architecture

The kernel is a connector between the hardware and the user application. It not only manages the resources and memory but also hides all the complexity and the interactions. Nowadays, User space and kernel space are the two divisions seen in modern computers. The structure and position of the kernel are shown in the image which is in the middle of hardware and software.

From the image, one will understand the relation of the kernel with the other components.

Components of Linux Kernel Architecture

All the kernel components and its modules are described below:

Process Scheduler

The process scheduler is the most important subsystem in the Linux kernel because it not only processes the control of the CPUs but also it controls the other subsystems. The process scheduler is divided into four main modules:

System call interface.
Scheduling Policy.
Architecture Independent Scheduler.
Architecture Specific Scheduler.

All the other subsystems depend on it to suspend and resume the process and functions in response to the hardware request.

Memory Manager

The memory manager is responsible for the control process and it manages the hardware’s resource memory. This memory manager redistributes the unused memory into persistent memory by swapping which increases the virtual memory. It has three main modules:

System call Interface.
Architecture Independent scheduler.
Architecture Specific Scheduler.

Virtual File System

The virtual file system is the system that shows data stored on the hardware device. It allows the mounting of any logical system on a physical device. It also loads the executable programs. The modules of the virtual file system:

Device Driver
Device Independent Interface
Logical system
System call interface
System Independent Interface.

Inter-Process Communicator

Inter-process communicator is the subsystem that is responsible for the communication and data exchange between the process scheduler and memory manager as well as other operating subsystems.

Network Interface

A network interface is a component of the kernel that allows the Linux system to connect with other devices over a network. Several hardware devices and networks are used by the network interface. Moreover, user processes and other kernel subsystems can access the network without knowing the configuration. It includes the modules which are the network device driver, device-independent Interface, Network Protocol, System Interface, and Protocol Independent Interface.

How Linux Kernel Works

It is important to understand how the Linux kernel works to understand the core mechanism. The working flow of the Linux kernel is:

Firstly, the Linux kernel should be loaded and booted.
The kernel initializes the other system including device drivers and starts its job which is shown below:
- Memory Management: Manages the hardware memory and pre-processes the memory mapping and swapping.
- Resource Management: Enabling the executable programs it manages and utilizes the resources.
- Security Management: Provide restrictions to the user processes and protection by the end-to-end encryption process.
- Process Management: Schedule the processes according to the high to low level and execute the programs.
Then the process is executed and sends the system calls.
After Switching into the kernel mode, the system calls are executed.

5 key Features of Linux kernel

The features mainly make the kernel unique and different from other OS and also make it popular. Let’s see some key features below:

1. Open Source

Open source means the source code of the kernel is open and can be modified by anyone. Other facilities that include are:

Open-source characteristics have made it more versatile.
Increases the customizability as the kernel mode can be modified by any developer.
Improvements are undergone because of the kernel modification.

2. Monokernality

Because having a mono-kernel, the kernel provides the following advantages:

Tight integration: Provides by communicating with other sub-systems and optimizing the complex functionalities. This feature provides:
Efficiency: As for every system call it does not need to change the mode so it increases the efficiency.
Lower Latency: It directly handles the system call and interrupts which lowers the latency.

3. Simplicity

The monolithic kernel is the simplest structure that can be designed, debugged, and implemented very easily. Its simplicity makes it easy for the developers to understand the core mechanism.

4. Security

Linux kernel is stable and secure to use. As a multiuser OS, the kernel space is separated from the user space. The key security features that the kernel provides are shown below:

User-based permission model which provides encryption and file system permission.
Capability to remove the potentially unsafe component.
Isolated process space.
Secure extensible Inter-process communication.

5. Scalability

Scalability means the ability of the kernel to efficiently utilize hardware resources and adapt its performance as the system’s load increases. Due to the huge scalability property of the Linux kernel, users can use it from the embedded system to the hardware level. Also, it provides multi-process management and a large amount of memory management.

Conclusion

This article illustrates the type, architecture, working principles, and features of the Linux kernel. By reading the article one can understand the mechanism of the core component which nature makes it use from wearable devices to supercomputers to cloud servers. With its unique features, stable and mature kernel code, and being a collaboratory kernel project, it has gained huge popularity all over the world.