I don't understand a simple scheduling problem
suppose we have the four jobs: j1, j2, j3, j4
and associated running times: t1=15,t2=8,t3=3,t4=10
only one processor
schedule 1:j1->j2->j3->j4 0->15->23->26->36 avg time:25
schedule 2:j3->j2->j4->j1 0->3->11->21->36 avg time:17.75
Why the 2 is better than 1? The total running times are the same
I mean it always takes 36 to finish all the jobs.So what's the difference?
Who can provide me an example to help me understand?
Thank you
and associated running times: t1=15,t2=8,t3=3,t4=10
only one processor
schedule 1:j1->j2->j3->j4 0->15->23->26->36 avg time:25
schedule 2:j3->j2->j4->j1 0->3->11->21->36 avg time:17.75
Why the 2 is better than 1? The total running times are the same
I mean it always takes 36 to finish all the jobs.So what's the difference?
Who can provide me an example to help me understand?
Thank you
1: j1->j2->j3->j4
t1=15,t2=8,t3=3,t4=10
0->15->23->26->36
avg time : 25
2: j3->j2->j4->j1
t3=3,t2=8,t3=10,t4=15
0->3->11->21->36
avg time : 17.75
Simply the sum (or total) of (1) starts with a larger & bigger number compared to that of (2), and the big numbers add up. And when you get the average number out of it, the result should be clear.
15 + 23 + 26 + 36 = 100
100 / 4 = 25
3 + 11 + 21 + 36 = 71
71 / 4 = 17.75
t1=15,t2=8,t3=3,t4=10
0->15->23->26->36
avg time : 25
2: j3->j2->j4->j1
t3=3,t2=8,t3=10,t4=15
0->3->11->21->36
avg time : 17.75
Simply the sum (or total) of (1) starts with a larger & bigger number compared to that of (2), and the big numbers add up. And when you get the average number out of it, the result should be clear.
15 + 23 + 26 + 36 = 100
100 / 4 = 25
3 + 11 + 21 + 36 = 71
71 / 4 = 17.75
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