kontekstinvaihtojen

Kontekstinvaihto, also known as context switching, is a fundamental concept in operating systems and computer science. It refers to the process of saving the state of one process or thread so that it can be restored and resumed later, and then loading the saved state of another process or thread. This allows a single CPU to appear to run multiple tasks concurrently.

The state that is saved during a context switch typically includes the program counter, CPU registers, memory management information, and other process-specific data. When a context switch occurs, the operating system's scheduler decides which process or thread will run next. If the currently running process is preempted, its state is saved, and the state of the next process is loaded. This enables time-sharing, where multiple users or applications can share a computer's resources.

Context switching is essential for multitasking and interactive computing. Without it, a computer would only be able to execute one program at a time. However, context switching is not without its overhead. The process of saving and restoring state takes time, which can impact overall system performance. Therefore, operating system designers aim to minimize the frequency and cost of context switches. Factors that influence context switching include the number of processes, the scheduling algorithm, and the hardware architecture. Efficient context switching is a key indicator of an operating system's responsiveness and throughput.