Q51➡| NTA UGC NET November 2017 Paper-3 Consider the following four processes with the arrival time and length of CPU burst given in milliseconds : The average waiting time for preemptive SJF scheduling algorithm is_______.
Q52➡| NTA UGC NET November 2017 Paper-3 Consider a virtual page reference string 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1 Suppose a demand paged virtual memory system running on a computer system such that the main memory has 3 page frames. Then________ page replacement algorithm has minimum number of page faults.
Q53➡| NTA UGC NET November 2017 Paper-3 User level threads are threads that are visible to the programmer and are unknown to the kernel. The operating system kernel supports and manages kernel level threads. Three different types of models relate user and kernel level threads. Which of the following statements is/are true ? (A)- (i) The Many – to – one model maps many user threads to one kernel thread (ii) The one – to – one model maps one user thread to one kernel thread (iii) The many – to – many model maps many user threads to smaller or equal kernel threads (B)- (i) Many – to – one model maps many kernel threads to one user thread (ii) One – to – one model maps one kernel thread to one user thread (iii) Many – to – many model maps many kernel threads to smaller or equal user threads
Q54➡| NTA UGC NET November 2017 Paper-3 Consider a system with five processes P0 through P4 and three resource types A, B and C. Resource type A has seven instances, resource type B has two instances and resource type C has six instances suppose at time T0 we have the following allocation. If we implement Deadlock detection algorithm we claim that system is_____.
Q55➡| NTA UGC NET November 2017 Paper-3 Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 37, 122, 14, 124, 65, 67 Suppose SSTF disk scheduling algorithm implemented to meet the requests then the total number of head movements are_____if the disk head is initially at 53.
Q57➡| NTA UGC NET November 2017 Paper-3 Consider the following statements : (A) . UNIX provides three types of permissions Read Write Execute (B). UNIX provides three sets of permissions permission for owner permission for group permission for others Which of the above statement/s is/are true ?
Q58➡| NTA UGC NET November 2017 Paper-3 Which of the following routing technique / techniques is / are used in distributed systems ? (A) Fixed Routing (B) Virtual Routing (C) Dynamic Routing
Q59➡| NTA UGC NET November 2017 Paper-3 Match the following WINDOWS system calls and UNIX system calls with reference to process control and File manipulation.
Q60➡| NTA UGC NET November 2017 Paper-2 In___________disk scheduling algorithm, the disk head moves from one end to other end of the disk, serving the requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without serving any requests on the return trip.
Q61➡| NET November 2017 Paper-2 Suppose there are six files F1, F2, F3, F4, F5, F6 with corresponding sizes 150 KB, 225KB,75 KB, 60 KB, 275 KB and 65 KB respectively. The files are to be stored on a sequential device in such a way that optimizes access time. In what order should the files be stored ?
Q64➡| NTA UGC NET January 2017 Paper-3 A memory management system has 64 pages with 512 bytes page size. Physical memory consists of 32 page frames. Number of bits required in logical and physical address are respectively:
Q65➡| NTA UGC NET January 2017 Paper-3 Consider a disk queue with I/O requests on the following cylinders in their arriving order: 6, 10, 12, 54, 97, 73, 128, 15, 44, 110, 34, 45 The disk head is assumed to be at cylinder 23 and moving in the direction of decreasing number of cylinders. Total number of cylinders in the disk is 150. The disk head movement using SCAN-scheduling algorithm is:
i ➥ 172
ii ➥ 173
iii ➥ 227
iv ➥ 228
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Q67➡| NTA UGC NET January 2017 Paper-3 Some of the criteria for calculation of priority of a process are: (1) Processor utilization by an individual process. (2) Weight assigned to a user or group of users. (3) Processor utilization by a user or group of processes.
In fair share scheduler, priority is calculated based on:
Q72➡| NTA UGC NET January 2017 Paper-2 Which of the following statement(s) regarding a linker software is/are true ? I- A function of a linker is to combine several object modules into a single load module. II– A function of a linker is to replace absolute references in an object module by symbolic references to locations in other modules.
Q73➡| NTA UGC NET January 2017 Paper-2 There are three processes P 1 , P 2 and P 3 sharing a semaphore for synchronizing a variable. Initial value of semaphore is one. Assume that negative value of semaphore tells us how many processes are waiting in queue. Processes access the semaphore in following order : (1) P 2 needs to access (2) P 1 needs to access (3) P 3 needs to access (4) P 2 exits critical section (5) P 1 exits critical section The final value of semaphore will be :
Q73➡| NTA UGC NET January 2017 Paper-2 In a paging system, it takes 30 ns to search translation Look-aside Buffer (TLB) and 90 ns to access the main memory. If the TLB hit ratio is 70%, the effective memory access time is :
Q75➡| NTA UGC NET January 2017 Paper-2 Which of the following scheduling algorithms may cause starvation ? 1. First-come-first-served 2. Round Robin 3. Priority 4. Shortest process next 5. Shortest remaining time first
Q77➡| NTA UGC NET August 2016 Paper-3 In Unix operating system, when a process creates a new process using the fork () system call, which of the following state is shared between the parent process and child process?
Q80➡| NTA UGC NET August 2016 Paper-3 Suppose that the time to do a null remote procedure call (RPC) (i.e. 0 data bytes) is 1.0 msec, with an additional 1.5 msec for every 1K of data. How long does it take to read 32 K from the file server as 32 1K RPCs ?
Q83➡| NTA UGC NET August 2016 Paper-3 In Unix, files can be protected by assigning each one a 9-bit mode called rights bits. Now, consider the following two statements: I. A mode of 641 (octal) means that the owner can read and write the file, other members of the owner’s group can read it, and users can execute only. II. A mode of 100 (octal) allows the owner to execute the file, but prohibits all other access. Which of the following options is correct with reference to the above statements ?
Q84➡| NTA UGC NET August 2016 Paper-2 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.
Q85➡| NTA UGC NET August 2016 Paper-2 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: With reference to current allocation, is system safe ? If so, what is the safe sequence ?
Q86➡| NTA UGC NET August 2016 Paper-2 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 blocks requests are: 98, 37, 14, 124, 65, 67
Q87➡| NTA UGC NET August 2016 Paper-2 In UNIX,_________creates three subdirectories : ‘PIS’ and two subdirectories ‘progs’ and ‘data’ from just created subdirectory ‘PIS’.
Q88➡| NTA UGC NET August 2016 Paper-2 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 next process to be scheduled. If the process have no I/O operations and all arrive at time zero, then the scheduler implements__________criteria.
