Process management

Question

In a single core processor, with Round Robin scheduling, how does the CPU keep track of time when a time quantum expires and brings in another process?

Answer 1

CPU don't actually keep track of the time.

Let the scheduling algorithm is Round Robin then when the process has done with the time quantum time (Round Robin scheduling has it's fixed time quantum time) Then According to algorithm there would be an Interrupt generated (Time slice complete interrupt) and then the Short Term scheduler then schedule new process from ready queue.

tell me if something is not clear yet.

Comments

No.Short Term Scheduler (CPU Scheduler) has nothing to do with context switching.

STS only select which process to allocate CPU after receiving kind of signal(interrpt) that means , hey! you STS select which process to pick from ready queue for actal execution.

It's Dispatcher , OS modle which deals with context switching and actually allocate CPU to selected process by STS.

read  more here

https://en.wikipedia.org/wiki/Scheduling_(computing)

---

Ok thanks @RupendraChaudhary sir got your point but u didn't answere that all 3 schedulers effect the performance of the system..??

---

This is an trivial question sahil.They are schedulers so of course if they don't do their work properly , system performance will have to suffer. Or in another way tell me what do you mean by system performance then i can be more specific.

STS speed must be fast enough because CPU do it's work very quickly. If there is less physical memory and MTS is not swapping then it's an bad impact on multiprogramming. It's responsibility of LTS to select combination of i/o bound and cpu bond processes in that way system performance will be good.