Questions
Consider a buddy system memory allocation where the size of a free memory segment is 256 KB, and the memory of kernel is 33 KB. To fulfill the request of memory allocation, a memory block of size M from free memory pool is allocated. What is the size of M?
- 33 KB
- 64 KB
- Two blocks, one of size 32 KB and other of size 1KB
- Two blocks each of size 32 KB
- 256 KB will be allocated
Find out the total size of internal fragmentation in case of first fit algorithm.
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- 609 KB
- 659 KB
- 719 KB
- 599 KB
- None of these
Consider a set of n tasks with known runtimes, r1, r2, ........r3 to be run on a uniprocessor machine. Which of the following processor scheduling algorithms will result in the maximum throughput?
- Round-robin
- Shortest-Job-First
- Highest-Response-Ratio-Next
- First-come-First-Served
The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by
- the instruction set architecture
- page size
- physical memory size
- number of processes in memory
Consider the following set of processes, with the arrival time and the CPU-burst time given in milliseconds.
What is the average turnaround time for these processes using the algorithm shortest remaining processing time first (SRPT)?
- 5.50
- 5.75
- 6.00
- 6.25
Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4 KB, what is the approximate size of the page table?
- 16 MB
- 8 MB
- 2 MB
- 24 MB
Consider the following statements with respect to user-level threads and kernel-supported threads
(i) Context which is faster with kernel-supported threads
(ii) For user-level threads. a system call can block the entire process
(iii) Kernel-supported threads can be scheduled independently
(iv) User-level threads are transparent to the kernel
Which of the above statements are true?
- (ii),(iii) and (iv) only
- (ii) and (iii) only
- (i) and (iii) only
- (i) and (ii) only
Consider an operating system capable of loading and executing a single sequential user process at a time. The disk head scheduling algorithm used is First Come First Served (FCFS). If FCFS is replaced by shortest seek Time Fist (SSTF), claimed by the vendor to given 50% better benchmark results, what is the expected improvement in the I/O performance of user programs?
- 50%
- 40%
- 25%
- 0%
Suppose $n$ processes, $P_1, \dots P_n$ share $m$ identical resource units, which can be reserved and released one at a time. The maximum resource requirement of process $P_i$ is $s_i$, where $s_i > 0$. Which one of the following is a sufficient condition for ensuring that deadlock does not occur?
- $\forall i,\: s_i, < m$
- $\forall i, \:s_i < n $
- $\Sigma_{i=1}^n \: s_i < (m+n)$
- $\Sigma_{i=1}^n \: s_i < (m \times n)$
Consider the following code fragment:
if (fork()==0
{a = a + 5; print f (%d,%/na, and a);}
else {a − 5; print f (%d,%d/n,a,&a);}
Let u, v be the values printed by the parent process, and x,y be the values printed by the child process. Which one of the following is TRUE?
- u = x + 10 and v = y
- u = x + 10 and v $\ne$ y
- u + 10= x and v = y
- u + 10 = x and v $\ne$ y
Consider a FIFO page replacement algorithm containing three frames. Initially, there is no page loaded in any of the frames. If the system first accesses 60 distinct pages in some order and then accesses the same pages in reverse order, calculate the total number of page faults.
- 120
- 114
- 117
- 60
- None of these
In demand paging, if average page fault service time is 7 millisecond, memory access time is 150 nanoseconds. A process 'P' executes successfully without replacing any frame. What is the effective access time?
- Insufficient data
- 3500075 milliseconds
- 150 nanoseconds
- 7 milliseconds
- 7000150 milliseconds
If a page fault occurs in step 5, which of the step(s) will execute again?
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- Step 1 to step 5
- Step 2 to step 5
- Step 3 to step 5
- Step 4 and step 5 only
- Step 5 only
Consider two processes P1 and P2 accessing the shared variables X and Y protected by two binary semaphores Sx and Sy respectively, both initialized to 1. P and V denote the usual semaphore operators, where P decrements the semaphore value and V increments the semaphore value. The pseudo-codes of P1 and P2 are as follows:
In order to avoid deadlock, the correct operators at L1,L2,L3 and L4 are respectively
- P(SY),P(SX);P(SX),P(SY)
- P(SX),P(SY);P(SY),P(SX)
- P(SX),P(SX);P(SY),P(SY)
- P(SX),P(SY);P(SX),P(SY)