Download DU (University of Delhi) B-Tech 3rd Semester 1566 Operating System Question Paper

Download DU (University of Delhi) B-Tech (Bachelor of Technology) 3rd Semester 1566 Operating System Question Paper

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Roll No.
S. No. onueslion Paper : 1566
Unique Paper Code : 2341301 ? F?3
Name of the Paper : Operating System
Name of the Course : B.Tech. in Computer Science '
'S?mester ' : 111
Duration :3 Hours - ? Maximum Marks : 75?
(b)
(C)
(Write your Roll No. on the top immediately on receipt of this question paper.)
I
Section A is compulsory. Attempt any 4 questiox?ls from Section B.
Parts of a question must Be answered together.
SECTION A.
Name thg scheduler resporisible f0} : .
(1) I sWapping out partially executed programs
1 (ii) controlling the degree of multiprogramxhing '
(iii) shifting a process frbm ready state to ninning?tate ? _
(iv) selecting a proper mix 6f CPU bound andiI/O bound processes. , 2
List.an.~advat'1tage and a disadvant?ge 6f integrating the user interface into the operating
What may happen if getting the value(s) of- fhe following fegisters is not prix?il?igea ? I
(1') CPU time; ? '1
(i1) baseregister?and limitre'gi'ster " . I _ . 2
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(d) Differentiate between the following :
I (e)
'(g)
02')"
2(1)"
_ (n
. (/2)
' (I)
(m)
(i) system calls and system programs
(ii) user level thread and kernel level thread
(iii) paging and d?emandpaging. ' I . 2 ' 3x2
Assume that you have a page-reference string for a prece?s with m ?fra'mes (initially al]
empty): The page reference string has length p; n distinctpagehumbers occur in it. Answer,
these questions for any page? replacement algorithm. I
(i) What is the-lewer bohnd on?the number of page faults ?
(i1) - What is the upper bound on the number of page faults ? ? I '2
What is the pur.pcl)ise of keeping, open ?le tatble by operating system ? . I 2
fWhat' ?is 'need-tol-knox'y principa! 1? I V I i ? i 2
Explaihi'any two program threats. , 2 ? ~_ ' ? ' - . 2 .2
' What ,are the-dvo ways 19 specify the. 'pathnarrtes in tree stritctilred direetorives ? 2 .
What ?re the' ehallehges'fl?aeed'by developers of handheld devices ?2 2 _ _ ? ? 2 ?2
?What is e dispatcher and give its various ?mctiohs ?. 2, ' 2 ' I l, ' ? 2
J Why is rouhd;robih algorithm afso 'catled as proceesof.shafing ? 2 . -_2
List foqf necessary leonditions: forfde'adleck to OGCl-Ilf?i-n the systetn. . l 2 ~ 2
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(11) How many processes are created by the program segment given below ?.7 Justify your
answer.
mainO
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(o) ? De?ne transfer rateand positioning time With rgs?e?t to magnetic disk. 3
SECTION B
2.' (a) D Consider th? fbllowihg set of processes, with the length ?of CPU burst time given in
D?rocess ? _ VAnl'ival'Tih?me' I 3th Tide - " Priority
?Pl ' - f ' 07?. ' ,8 V. 4- _.
P2 2, 5 3
P3 D 3" _. 6 2
P4 5 2 1
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(b)
(a) '
(b)
1 4 ) , 1506?
(1') Draw Gantt charts illustrating the execution of these processes using :
(a) Shortest remaining time ?rst
(b) Priority based (non-preemptive)
(c) Round robin with time quantum = 3
(1'1) -What is the turnaround time of every process for each of the scheduling algorithrhs
given in part (i) ? . 3+3
What is race condition ? Give an example to show race between two different
processes ? 1 - I .' 4,
Consider a paging system with the page table stored in memory.
(1) if a memory reference takes 200 nanoseconds, how long does a. paged memory
reference take ?
(ii) if We add TLBs arid 75% of all page table references are found in the TLBs,
- what 15 the e??ective memory access time ? Assume that the time taken to access
A a TLB is 20 nanoseconds. ? 1 - 7 . . 1+3.
7
ConSider the following memory address references :
. .0030, '0012, 0315, 0104 0185 0445, 0467, 021.,5 0732, 0749, 0752, 0612, 0204,
. 0239 0226, 01738, 0184, 0426 0781, 0381, 0261, 0286, 0278, 0257, 0189, 0289,
_ 0146, 0178.
i What will the refe?rehce- string con?esponding to the addresses given above (assuming page
' siZe is 100 bytes) ? Determine the number of page faults fer optimal page replacement
' algorithm. Assume that there are three frames and all of them? are initially empty. 2+4 '

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(0) Suppose the read/write head is at track 97. moving towards track 199 (the highest numbered
track on the dlSk) and the disk request queue contains read/write requests for the sectoxs
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on tracks 34, 155, io3, 96 and 197, respectively. What is the tetal number of head
movements needed to satisfy the requests in the queue Using :
(I) SCAN
(ii) c-Loom ? 6
(b) How are threads di?'erent ?'om processes ? Give an example (an environment/applicatlon)
5 where threads ?u'e more appropriate than processes. 4
(a) Draw a resource allocation graph for the-fbllowing data :
P = {P1,?P2, P3}
EIV= {P -> R], R1'> P3, P2 '> RI, R2 '> 92? R3 '> P2: P3 '> R3}.
The number of Instances of RI and R3 is l and R2 18 2.
Is there a cycle 1n the graph 7 Is the system in a deadlock state ? If not, then give
reason.
P.T.O.
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(b) Explain the three disadvantages of linked allocation. Which disadvantage can be overcome
using FAT and how ? V 5
Write short notes (any two) :
(z) Microkcmel apprqach
(it) Real time operating system
(in) Segmentation. - ' 5+5