ISRO-2013-53

Question

A CPU scheduling algorithm determines an order for the execution of its scheduled processes. Given 'n' processes to be scheduled on one processor, how many possible different schedules are there?

• A. $n$
• B. $n^{2}$
• C. $n!$
• D. $2^{n}$

Answer 1

preemptive= infinite way

non preemptive=n!

option=C

Comments

In all case n! Only

---

no , only for nonpreemptive it will be n!

because, it takes 1 process at a time and completes it

So, 1st process can executes n ways

2nd process can execute (n-1) ways

3rd process can executes (n-2) ways......

So, n process can executes n! ways

---

I did n't get why in case of pre-emption allowed , Why there can be infinite combination , assuming that time quantum tends to 0 and Burst time tending to NP hard problems (a silly way to say infinte) , still  if one  of the process is scheduled by CPU then , if suspended it is not the responsiblity of CPU  again (long term schedular) to schedule it again, rather the duty of Middle term schedular.