Etujärjestys

Etujärjestys, also known as priority scheduling, is a scheduling algorithm used in operating systems to determine the order in which processes are executed by the CPU. In this algorithm, each process is assigned a priority, and the CPU executes the process with the highest priority first. If two processes have the same priority, they are typically executed in the order they arrived in the queue.

The priority of a process can be determined by various factors, such as the type of process, the amount of CPU time it has already used, or the amount of time it has been waiting in the queue. The priority can be either static, meaning it does not change over time, or dynamic, meaning it can change based on certain conditions.

Priority scheduling can be either preemptive or non-preemptive. In preemptive priority scheduling, the CPU can interrupt the currently running process if a new process with a higher priority arrives. In non-preemptive priority scheduling, the CPU will continue to execute the current process until it is completed or blocked.

One of the main advantages of priority scheduling is that it can provide a more responsive system for high-priority processes. However, it can also lead to starvation, where low-priority processes may never get executed if high-priority processes are constantly arriving. To mitigate this, some systems use aging, where the priority of a process is gradually increased as it waits in the queue.