Kernel Level Threads in Operating System

Pre-requisites: Thread in Operating System

An operating system is a program loaded into a system or computer. and manage all the other program which is running on that OS Program, it manages the all other application programs. or in other words, we can say that the OS is an interface between the user and computer hardware.

So, in this article, we will learn about the Kernal Level Threads in Operating Systems. and understand are required terms with respect to knowing more about the Kernel Level Threads in the Operating system. 

What are Kernel Level Threads?

In operating systems basically, the threads are the unit of execution within a process. and the kernel level threads are also kinds of threads which is directly handled via kernel threads management. The Kernel-level threads are directly handled by the OS directly whereas the thread’s management is done by the kernel.

In the Kernel Level Threads, Each thread is self-organizing and the kernel provides each thread with its own context with information about the thread’s status, such as its name, group, and priority.

Example – The example of Kernel-level threads are Java threads, POSIX threads, etc.

Features of Kernel-Level Threads 

So there are some of the features of Kernel-level threads as listed here.

• It is basically implemented by Operating System.
• These threads have more Context switch time.
• Kernel-Level Threads can be determined as multithreaded.
• Scheduling multiple threads that belong to the same process on different processors is possible in kernel-level threads.

Advantages of the Kernel-Level Threads 

In OS the Kernel-Level Threads offer several kinds of advantages.

1. The Kernel Level Threads also behave like a multithreaded.
2. Kernel-Level Threads are more aware of remaining the threads.
3. They are managed by the kernel.
4. In terms of context switching and scheduling the Kernel-Level Threads are more efficient compared to user-level threads.
5. Kernel-Level Threads have the control of multiple processors or cores to execute threads concurrently.

Disadvantages of the Kernel-Level Threads 

There are also some disadvantages to using the Kernel-level threads as listed here.

1. As the Kernel-level threads have control over the threads, so it’s very complex when we implement any thread synchronization techniques.
2. The kernel is responsible for managing all threads and creating and destroying threads will have more overhead.
3. The Kernel-level threads are slower to create and also manage the threads compare to User-level threads.

In general, kernel-level threads are an essential part of modern operations and are widely used in many applications, including web servers, databases, and computer science applications. The Kernel-level threads have some features and advantages that show their functionality.

Kernel-level threads (KLTs) are threads that are managed directly by the operating system kernel. Unlike user-level threads (ULTs), KLTs are managed entirely in kernel space and do not require any user-level library or support.

Some characteristics of KLTs include:

1. Thread management: KLTs are managed directly by the operating system kernel, which provides scheduling, synchronization, and communication mechanisms.
2. Kernel-level context switching: KLTs switch context at the kernel level, which typically involves saving and restoring the entire processor context, including registers, program counter, and stack pointer.
3. Resource allocation: KLTs are allocated kernel-level resources such as CPU time, memory, and I/O devices.
4. Scalability: KLTs can take advantage of hardware resources such as multi-core processors, as the kernel can schedule threads across multiple processors.
5. Performance: KLTs can provide better performance than user-level threads, as they do not require any user-level library or support, and can take advantage of kernel-level optimizations.

However, KLTs also have some drawbacks, such as:

1. Overhead: KLTs have higher overhead than ULTs, as context switching at the kernel level requires more resources and time.
2. Scalability: While KLTs can take advantage of hardware resources, they may also suffer from scalability issues, as the kernel may become a bottleneck for managing large numbers of threads.
3. Portability: KLTs are highly dependent on the operating system kernel and may not be portable across different systems.

Overall, KLTs provide a powerful mechanism for managing threads at the kernel level, but also have some drawbacks. When designing a multithreaded application, it is important to consider the trade-offs between ULTs and KLTs and choose the appropriate threading model based on the requirements of the application.