check the quesion

Question

consider a uniprocess system executing four tasks T1,T2,T3 and T4 each of which is composed of an 10 sequence of job(or instances) which are arrives at periodically at interval of 2,4,8 and 16 ms respectively.the priority of each task is directly proportional to its periods and the avaliable task are schedule in order of priority,with the highest priority task schedule first.each instance of T1,T2,T3 and T4 requires an execution time 1,2,4 and 6 ms respectively.given that all task arrive at beginning of the  2ms and task preempted allowed,the 2nd instance of T3 its execution at the end of_______ ms

Answer 1

execution sequence....

1).............................

2)T4

3)T4

4)T4

5)T4

6)T4

7)T4

8)T3

9)T3

10)T3

11)T3

12)T2

13)T2

14)T1

15)................................

16)T4

17)T4

18)T4

19)T4

20)T4

21)T4

22)T3

23)T3

24)T3

25)T3....

so ans according to me is 25 ms..

please let me know,if it is correct or not.... 

Comments

yes @Sayantan it will be 25ms.

Answer 2

Answer will be 25 ms

As priority of job is directly proportional to its period 

So T₄ has highest priority and T₁ has lowest priority

So, execution sequence

1. T₄
2. T₄
3. T₄
4. T₄
5. T₄
6. T₄
7. T₃
8. T₃
9. T₃
10. T₃
11. T₂
12. T₂
13. T₁
14. _ (All jobs are in interval here)
15. T₃
16. T₃
17. T₄
18. T₄​
19. T₄
20. T₄
21. T₄
22. T₄
23. T₃
24. T₃

_​Here all jobs arrived at the begining of 2 ms , So, total time(24+1)=25ms

Comments

how possible????source of the qs???

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i get T4 start at 2 ms completed at 8ms.T3 start at 8ms and completed at 12 ms.T2 start at 12ms and completed at 14ms and then T1 start at 14ms and completed at 16ms...but not T3

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in 2nd instance ans must be 25ms.i think ans they are given is wrong.