Stan Cao

A backend developer.

Scheduling - Time Sharing

less than 1 minute read

Aspect to analyse performance of scheduling policy

Turnaround time = Tcompletion - Tarrival

Response Time = Tfirst-run - Tarrival

Schedule Policy

  • FIFO: first in, first out
  • SJF: shortest job first
  • STCF: shortest time to complete first
  • RR: round robin, good for response time
  • Lottery: allocate a range for each process, get a random number to find it locates in which range and run that process

MLFQ: multi-level-feedback-queue

mlfq

  • priority A>B, run A. A=B, run in RR
  • new process in the top most queue
  • reduce time when its time slice used up
  • reset to top periodically, time to reset too long results in stravation for long running process, too short makes it runs like RR

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