Operating System

211. Consider the following page reference string: 1, 2, 3, 2, 4, 1, 3, 2, 4, 1. Assume that there are three page frames which are initially empty. Then, which of the following expressions is true?
Page reference string 1, 2, 3, 2, 4, 1, 3, 2, 4, 1 पर विचार कीजिए। यदि तीन page frames हों और वे शुरुआत में empty हों, तो निम्न में से कौन-सा expression सही है?
(DSSSB PGT Computer Science (Male) 27.07.2018 (Shift-II))
A. LRU = FIFO = OPTIMAL
B. FIFO < OPTIMAL = LRU
C. FIFO = OPTIMAL
D. OPTIMAL < FIFO < LRU

Correct Answer: D

Explanation (EN): For the given sequence, Optimal gives the fewest faults, FIFO is in between, and LRU gives the most faults.

Explanation (HI): दिए गए sequence में Optimal सबसे कम faults देता है, FIFO उससे अधिक, और LRU सबसे अधिक faults देता है।

212. Consider the reference string: 0, 1, 2, 3, 0, 1, 4, 0, 1, 2, 3, 4. If FIFO page replacement algorithm is used, then the number of page faults with three page frames and four page frames are _______ and _______ respectively.
Reference string 0, 1, 2, 3, 0, 1, 4, 0, 1, 2, 3, 4 पर विचार कीजिए। यदि FIFO page replacement algorithm उपयोग किया जाए, तो तीन page frames और चार page frames के लिए page faults क्रमशः कितने होंगे?
(UGC NET Computer Science June 2016 (Paper-II))
A. 10, 9
B. 9, 9
C. 10, 10
D. 9, 10

Correct Answer: D

Explanation (EN): For the given reference string, FIFO gives 9 page faults with 3 frames and 10 page faults with 4 frames.

Explanation (HI): दिए गए reference string पर FIFO, 3 frames के लिए 9 और 4 frames के लिए 10 page faults देता है।

213. If the disk head is located initially at track 32, find the number of disk moves required with FCFS scheduling criteria if the disk queue of I/O block requests are: 98, 37, 14, 124, 65, 67.
यदि disk head प्रारंभ में track 32 पर हो, तो FCFS scheduling में I/O block requests 98, 37, 14, 124, 65, 67 के लिए कुल disk moves कितनी होंगी?
(UGC NET Computer Science June 2016 (Paper-II))
A. 320
B. 322
C. 321
D. 319

Correct Answer: C

Explanation (EN): Adding the head movements in FCFS order gives 321 disk moves.

Explanation (HI): FCFS क्रम में head movements जोड़ने पर 321 disk moves मिलती हैं।

214. A scheduling algorithm assigns priority proportional to the waiting time of a process. Every process starts with priority zero (lowest priority). The scheduler reevaluates the process priority for every 'T' time units and decides the next process to be scheduled. If the processes have no I/O operations and all arrive at time zero, then the scheduler implements _______ criteria.
एक scheduling algorithm process की waiting time के proportional priority assign करता है। प्रत्येक process zero priority (lowest) से शुरू होती है। Scheduler हर 'T' time units पर priority का पुनर्मूल्यांकन करता है और अगले process को schedule करता है। यदि किसी process में I/O operation नहीं है और सभी time zero पर आते हैं, तो scheduler कौन-सा criteria implement करता है?
(UGC NET Computer Science June 2016 (Paper-II))
A. Priority scheduling
B. Round Robin Scheduling
C. Shortest Job First
D. FCFS

Correct Answer: B

Explanation (EN): This behavior is equivalent to Round Robin with quantum T.

Explanation (HI): यह व्यवहार quantum T वाले Round Robin Scheduling के equivalent है।

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