System Software and Operating System — Mock Test 14

______ system call creates new process in Unix.

At a particular time of computation, the value of a counting semaphore is 10. Then 12 P operations and “x” V operations were performed on this semaphore. If the final value of semaphore is 7, x will be :

In a paged memory, the page hit ratio is 0.40. The time required to access a page in secondary memory is equal to 120 ns. The time required to access a page in primary memory is 15 ns. The average time required to access a page is ________.

In a multi-user operating system, 30 requests are made to use a particular resource per hour, on an average. The probability that no requests are made in 40 minutes, when arrival pattern is a poisson distribution, is ______.

Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instructions privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O ?

Which UNIX/Linux command is used to make all files and sub-directories in the directory “progs” executable by all users ?

Which of the following statements are true ?

(a) External Fragmentation exists when there is enough total memory space to satisfy a request but the available space is contiguous.

(b) Memory Fragmentation can be internal as well as external.

(c) One solution to external Fragmentation is compaction.

Page information in memory is also called as Page Table. The essential contents in each entry of a page table is/are _________.

Consider a virtual page reference string 1, 2, 3, 2, 4, 2, 5, 2, 3, 4. Suppose LRU page replacement algorithm is implemented with 3 page frames in main memory. Then the number of page faults are_________.

Consider the following three processes, with arrival time and CPU burst time in milliseconds: P1 (arrival 0, burst 7), P2 (arrival 1, burst 4), P3 (arrival 2, burst 8). The Gantt chart for the preemptive SJF scheduling algorithm is

In which of the following scheduling criteria, context switching will never take place?