Scheduling based on process priority levels
Priority scheduling is a CPU scheduling algorithm where each process is assigned a priority, and the process with the highest priority is selected for execution. Priorities can be assigned based on various criteria such as process importance, resource requirements, user class, or other system-defined metrics. Priority scheduling can be either preemptive (higher priority process can interrupt a running lower priority process) or non-preemptive (once a process starts, it runs to completion regardless of priority). Processes with equal priority are typically scheduled using FCFS. The main advantage of priority scheduling is that it allows important processes to receive preferential treatment, which is useful in real-time systems and situations where certain tasks are more critical than others. However, priority scheduling can lead to starvation of low-priority processes if higher priority processes continuously arrive. This issue is often addressed through aging techniques that gradually increase the priority of waiting processes. Implementation requires maintaining the ready queue as a priority queue ordered by process priority. Priority scheduling is widely used in modern operating systems, often in combination with other algorithms in multilevel queue systems.