Kernelsäien

Kernelsäien is a term originating from Swedish and can be translated to "kernel threads" in English. It refers to the threads that are managed and executed directly by the operating system's kernel. Unlike user-level threads, which are managed by a user-space library and are not directly visible to the kernel, kernel threads are known to the kernel scheduler. This means the kernel is aware of each kernel thread and can independently schedule them for execution on available CPU cores.

The primary advantage of kernel threads is their ability to run in parallel on multi-core processors. If one kernel thread is blocked waiting for an I/O operation, other kernel threads can continue to run. This significantly improves the responsiveness and performance of applications, especially those that are I/O-bound or computationally intensive. The operating system's kernel manages the creation, termination, and context switching of these threads.

However, managing kernel threads incurs some overhead. The kernel needs to maintain data structures for each thread, and context switching between them involves saving and restoring more state compared to user-level threads. This overhead can make kernel threads less efficient for applications that require a very large number of threads. Despite this, kernel threads are fundamental to modern operating system design, enabling efficient multitasking and concurrency. Many programming languages and libraries abstract away the direct management of kernel threads, providing higher-level threading primitives to developers.