Q. The directory can be viewed as _______ that translates filenames into their directory entries.

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Q. Consider the following justifications for commonly using the two-level CPU scheduling :

I. It is used when memory is too small to hold all the ready processes.

II. Because its performance is same as that of the FIFO.

III. Because it facilitates putting some set of processes into memory and a choice is made from that.

IV. Because it does not allow to adjust the set of in-core processes.

Which of the following is true?

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Q. For the implementation of a paging scheme, suppose the average process size be x bytes, the page size be y bytes, and each page entry requires z bytes. The optimum page size that minimizes the total overhead due to the page table and the internal fragmentation loss is given by

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Q. Which methods are utilized to control the access to an object in multi-threaded programming?

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Q. Various storage devices used by an operating system can be arranged as follows in increasing order of accessing speed:

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Q. How many disk blocks are required to keep list of free disk blocks in a 16 GB hard disk with 1 kB block size using linked list of free disk blocks? Assume that the disk block number is stored in 32 bits.

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Q. Consider an imaginary disk with 40 cylinders. A request come to read a block on cylinder 11. While the seek to cylinder 11 is in progress, new requests come in for cylinders 1, 36, 16, 34, 9 and 12 in that order. The number of arm motions using shortest seek first algorithm is

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Q. An operating system has 13 tape drives. There are three processes PI, P2 & P3.1 Maximum requirement of PI is 11 tape drives, P2 is 5 tape drives and P3 is 8 tape drives. Currently, PI is allocated 6 tape drives, P2 is allocated 3 tape drives and P3 is allocated 2 tape drives. Which of the following sequences represent a safe state?

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Q. Monitor is an Interprocess Communication (IPC) technique which can be described as

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Q. A disk drive has 100 cylinders, numbered 0 to 99. Disk requests come to the disk driver for cylinders 12,26,24,4,42,8 and 50 in that order. The driver is currently serving a request at cylinder 24- A seek takes 6 msec per cylinder moved. How much seek time is needed for shortest seek time first (SSTF) algorithm ?

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Q. Let Pi and Pj be two processes, R be the set of variables read from memory, and W be the set variables written to memory. For the concurrent execution of two processes Pi and Pj, which of the following conditions is not true?

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Q. A LRU page replacement is used with four page frames and eight pages. How many page faults will occur with the reference string 0172327103 if the four frames are initially empty?

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Q. Match the following for operating system techniques with the most appropriate advantage :

List – I List – II

(a) Spooling (i) Allows several jobs in memory to improve CPU utilization

(b) Multiprogramming (ii) Access to shared resources among geographically dispersed computers in a transparent way

(c) Time sharing (iii) Overlapping I/O and computations

(d) Distributed computing (iv) Allows many users to share a computer simultaneously by switching processor frequently

Codes:
a b c d

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Q. Which of the following statements is not true for Multi-Level Feedback Queue processor scheduling algorithm?

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Q. What is the most appropriate function of Memory Management Unit (MMU)?

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Q. In ___________ allocation method for disk block allocation in a file system, insertion and deletion of blocks in a file is easy.

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Q. Consider a program that consists of 8 pages (from 0 to 7) and we have 4 page frames in the physical memory
for the pages. The page reference string is :
1 2 3 2 5 6 3 4 6 3 7 3 1 5 3 6 3 4 2 4 3 4 5 1
The number of page faults in LRU and optimal page replacement algorithms are respectively (without including initial page faults to fill available page frames with, pages) :

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Q. Which of the following statements is not true about disk-arm scheduling algorithms?

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Q. 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.

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Q. Suppose there are four processes in execution with 12 instances of a Resource R in a system. The maximum need of each process and current allocation are given below:
Process Max. Need Current Allocation
P1 8 3
P2 9 4
P3 5 2
P4 3 1

With reference to current allocation, is system safe? If so, what is the safe sequence?

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