1) What is the swap space in the disk used for? (a) Saving temporary html pages (b) Saving process data (c) Storing the super-block (d) Storing device drivers Answer (B) 2) Increasing the RAM of a computer typically improves performance because: (a) Virtual memory increases (b) Larger RAMs are faster (c) Fewer page faults occur (d) None of the above Answer (C) 3) Consider the following snapshot of a system running n processes. Process i is holding Xi instances of a resource R, 1 1 (D) min (Xp, Xq) > 1 Answer (B) Explanation: Since both p and q don’t need additional resources, they both can finish and release Xp + Xq resources without asking for any additional resource. If the resources released by p and q are sufficient for another process waiting for Yk resources, then system is not approaching deadlock. 4) Which of the following is NOT true of deadlock prevention and deadlock avoidance schemes? (A) In deadlock prevention, the request for resources is always granted if the resulting state is safe (B) In deadlock avoidance, the request for resources is always granted if the result state is safe (C) Deadlock avoidance is less restrictive than deadlock prevention (D) Deadlock avoidance requires knowledge of resource requirements a priori Answer (A) Explanation: Deadlock prevention scheme handles deadlock by making sure that one of the four necessary conditions don’t occur. In deadlock prevention, the request for a resource may not be granted even if the resulting state is safe. 5) In which one of the following page replacement policies, Belady’s anomaly may occur? (A) FIFO (B) Optimal (C) LRU (D) MRU Answer (A) Belady’s anomaly proves that it is possible to have more page faults when increasing the number of page frames while using the First in First Out (FIFO) page replacement algorithm. 6) The essential content(s) in each entry of a page table is / are (A) Virtual page number (B) Page frame number (C) Both virtual page number and page frame number (D) Access right information Answer (B) Explanation: A page table entry must contain Page frame number. Virtual page number is typically used as index in page table to get the corresponding page frame number. 7) In which one of the following page replacement policies, Belady’s anomaly may occur? (A) FIFO (B) Optimal (C) LRU (D) MRU Answer (A) Explanation: Belady’s anomaly proves that it is possible to have more page faults when increasing the number of page frames while using the First in First Out (FIFO) page replacement algorithm. 8) The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by a) the instruction set architecture b) page size c) physical memory size d) number of processes in memory Answer (A) 9) Let the time taken to switch between user and kernel modes of execution be t1 while the time taken to switch between two processes be t2. Which of the following is TRUE? (A) t1 > t2 (B) t1 = t2 (C) t1 < t2 (D) Nothing can be said about the relation between t1 and t2 Answer: – (C) 10) Which of the following statements are true? (GATE CS 2010) I. Shortest remaining time first scheduling may cause starvation II. Preemptive scheduling may cause starvation III. Round robin is better than FCFS in terms of response time (A) I only (B) I and III only (C) II and III only (D) I, II and III Answer (D) Expalanation: I) Shortest remaining time first scheduling is a preemptive version of shortest job scheduling. It may cause starvation as shorter processes may keep coming and a long CPU burst process never gets CPU. II) Preemption may cause starvation. If priority based scheduling with preemption is used, then a low priority process may never get CPU. III) Round Robin Scheduling improves response time as all processes get CPU after a specified time
Posted on: Mon, 25 Nov 2013 05:03:01 +0000
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