GATE - 2007 | OS | Consider n jobs J1, J2,......Jn such that job Ji has execution time

GATE - 2007 [Operating System]

Question:

Consider n jobs J₁, J₂,......J_n such that job J_i has execution time t_i and a non-negative integer weight w_i. The weighted mean completion time of the jobs is defined to be 

where T_i is the completion time of job J_i. Assuming that there is only one processor available, in what order must the jobs be executed in order to minimize the weighted mean completion time of the jobs?

A	Non-decreasing order of ti
B	Non-increasing order of wi
C	Non-increasing order of witi
D	None-increasing order of wi/ti

  

Solution:

Option (D) is Correct.

Like OS concept, execute job which have more completiontime in 1 sec i.e.,

find w_i/t_i for every process then arrange it in the decreasing order.

So, we get complete time is minimum always.

So answer is the non-increasing order of w_i/t_i.

 

Thank You