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Assignment 1, question 6

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Assignment 1, question 6
March 21, 2007 12:39PM
2 questions relating to the arrival times issue.

At one point, the processor stands idle, what do you indicate in your gantt chart, considering that the previous item has completed?

If I have two processors, with the second one arriving at the exact start of a new quantum, but the other process still need to execute, would the first one get its slice, or is it still first come first serve in the round robin, and the first process gets it slice before the next one gets its first slice?
Re: Assignment 1, question 6
March 21, 2007 08:52PM
i left the blank spaces. I suppose you could label them "idle" if you want.

my understanding is that if the 1st process was still waiting for its slice when the 2nd process arrived, then the FCFS scheme would take effect. but if the 1st process had just been processed, then as soon as the 2nd arrives, it will kick the 1st one out, and then it's round-robin from there.
avatar Re: Assignment 1, question 6
March 28, 2007 08:59PM
Is anyone getting negative numbers when calculating turn around time and waiting time.

Did i go terribly wrong somewhere?


or is the processor prediting the futureeye popping smiley
Re: Assignment 1, question 6
March 28, 2007 09:01PM
No negative numbers pal. You should have made a mistake somewhere.
avatar Re: Assignment 1, question 6
March 28, 2007 09:12PM
Thanks

Will attempt to redo
Re: Assignment 1, question 6
March 29, 2007 08:39PM
Yeah I've got negative numbers too! I've done it a few times and I keep getting the same results. It works fine if the scheduling algorithms were pre-emptive, but the question states "SJF without preemption" and "a non pre-emptive priority". I know I am doing this right 'cos I'm following it step by step from the textbook.
Re: Assignment 1, question 6
March 30, 2007 07:46PM
You should recheck your gantt charts. Are you using the formula given in the study guide?
Re: Assignment 1, question 6
March 30, 2007 08:38PM
Stoopid mistake! I somehow copied incorrect values of the Arrival time for certain processes. Got it right now. Are you guys sure its ok to leave a blank space/label "idle"? Just to make sure I'm on the right track - do you by any chance get exactly the same Gantt charts for SJF and Priority scheduling??

Regards
Re: Assignment 1, question 6
March 31, 2007 01:55PM
34898425 Wrote:
-------------------------------------------------------
> Stoopid mistake! I somehow copied incorrect values
> of the Arrival time for certain processes. Got it
> right now. Are you guys sure its ok to leave a
> blank space/label "idle"? Just to make sure I'm on
> the right track - do you by any chance get exactly
> the same Gantt charts for SJF and Priority
> scheduling??
>
> Regards

I do. I found this very weird and will check it again if I finish this Formal Logic and have some time left! But now that one other have the same result I feel a *bit* more assured winking smiley
Re: Assignment 1, question 6
March 31, 2007 04:18PM
Did anyone get the same average wait time for all 3 algorithms?
avatar Re: Assignment 1, question 6
March 31, 2007 08:02PM
I had all different Gantt charts and all different wait times. confused smiley

Anyway if its right or wrong we will know when we get the assignments back. Now days
its very difficult to say which is absolutely right or wrong.

Keep going everyone. Don't give up!
Re: Assignment 1, question 6
March 31, 2007 08:49PM
My maths was bit off - went over my calculations and picked up an error with my round robin wait times.

My SJF and priority still have the same wait times though.

Glad that one is over - gonna upload it now - although I really battled with question 5 - still don't know what they were looking for.
Re: Assignment 1, question 6
April 01, 2007 09:27AM
I got same waiting time for priority and SJF but a different one for RR. It is now better to move on and wait for the marked assignment or solution. There is no point in breaking heads with it. Good luck to you all.
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