What is priority scheduling

Priority scheduling algorithm executes the processes depending upon their priority. Each process is allocated a priority and the process with the highest priority is executed first. Priorities can be defined internally as well as externally. Internal priorities are decided by the system depending upon the number of resources required, time needed etc. whereas external priorities are based upon the time in which the work is needed or the amount being paid for the work done or the importance of process. Priority scheduling can be preemptive or non- preemptive.

Note –

• If two processes have the same priority then tie is broken using FCFS.
• The waiting time for the highest priority process is always zero in preemptive mode while it may not be zero in case of non preemptive mode