Scheduling

Scheduling

1. Scheduling make multi tasking possible and is carried out by a 'Scheduler'. The scheduler manages the time that different processes spend in the CPU. There are different algorithms that the scheduler can use

   • Round Robin. Here each process is given fixed periods of time and if it is not finished then it is put back into the queue so the next process can have its turn
   • Shortest Job first. This picks the job that will take the shortest time and run until it's finished. However it needs to know the time of each process
   • First Come First Serve. Here the first process to arrive will be dealt with until it's finished. Other processes that arrive hasve to wait untill the process is finsihed
   • Shortest Remaining time. Here the scheduler estimates the time of the process and then picks the one that will take the least amount of time. If a shorter process arrive it will run that one.
   • Multi-level feedback queues. This uses a number of queues, each with a different priority. The algorithm can move between the queues depending of the job behaviour.