# May/June 2011 Past paper - Q5

Posted by Vampyre
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 May/June 2011 Past paper - Q5 October 26, 2011 10:09AM Registered: 8 years ago Posts: 40 Rating: 0
hi guys/gals,

any one manage question 5 of this paper or have any thoughts on it ?
been looking at it for a while and getting no where :-(

 Re: May/June 2011 Past paper - Q5 October 26, 2011 10:28AM Registered: 8 years ago Posts: 55 Rating: 0
At the bottom of S1's tut 102 there's a whole example of almost the exact same question.
 Re: May/June 2011 Past paper - Q5 October 26, 2011 10:32AM Registered: 11 years ago Posts: 14 Rating: 0
Or.....

Tut 102, page 9, Section 4. Page Replacement....
to be excact.

 Re: May/June 2011 Past paper - Q5 October 26, 2011 02:32PM Registered: 11 years ago Posts: 111 Rating: 0
Mine was 0,1,2,0,3,1,3,2,0,4,3
What page fault rates did you get for a) FIFO, b) LRU and c) Optimal?
I got a) 6/11 b) 9/11 and c) 6/11

(c) has me worried since it sounds as if it should be the lowest of the lot.
 Re: May/June 2011 Past paper - Q5 October 26, 2011 02:48PM Registered: 10 years ago Posts: 114 Rating: 0
I got the same reduced string. Haven't done the page fault calculation yet - will get to it shortly and post back then.

The optimal replacement will be the lowest, but its not to say that in some situation the fault rate of another algorithm will produce the same rate as the optimal rate. Optimal is just going to be the lowest in every situation.

EDIT:
Yep, same fault rates as well...
 Re: May/June 2011 Past paper - Q5 October 26, 2011 06:23PM Registered: 9 years ago Posts: 31 Rating: 0
I haven't as yet tackled Q5, but from what I understand and the exercises done so far on Page replacement. Optimal replace should have the lowest fault rate.
Guess there is no need to worry @hexium
 Re: May/June 2011 Past paper - Q5 October 26, 2011 06:35PM Registered: 11 years ago Posts: 111 Rating: 0
Yes, I already confirmed with the lecturer. What was worrying me was that even my page faults were happening in exactly the same spots so for all intends and purposes, the FIFO and Optimal tables looked like I had just copied the one from the other.
 Re: May/June 2011 Past paper - Q5 October 26, 2011 08:44PM Registered: 11 years ago Posts: 14 Rating: 0
Q3.4

I get that the process cannot be safely granted.
However it already fails at the comparison with the Need.
Is that really worth 6 marks?
 Re: May/June 2011 Past paper - Q5 October 26, 2011 10:12PM Registered: 9 years ago Posts: 31 Rating: 0
Good luck everyone
 Re: May/June 2011 Past paper - Q5 October 26, 2011 10:59PM Registered: 7 years ago Posts: 7 Rating: 0
@Takadiyi - Yes - Work = max resource vector. They should match. Check 3.3 again

3.3 last part for Process P3:

Work = (3, 15, 8, 10) + (0,2,1,0)
= (3, 17, 9, 10)
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