OS Memory Management

Question 41

Consider a virtual memory system with FIFO page replacement policy. For an arbitrary page access pattern, increasing the number of page frames in main memory will

• always decrease the number of page faults
• always increase the number of page faults
• sometimes increase the number of page faults
• never affect the number of page faults

Question 42

Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table?

• 16 MB

• 8 MB

• 2 MB

• 24 MB

Question 43

Suppose the time to service a page fault is on the average 10 milliseconds, while a memory access takes 1 microsecond. Then a 99.99% hit ratio results in average memory access time of (GATE CS 2000)

• 1.9999 milliseconds
• 1 millisecond
• 9.999 microseconds
• 1.9999 microseconds

Question 44

Consider a system with byte-addressable memory, 32 bit logical addresses, 4 kilobyte page size and page table entries of 4 bytes each. The size of the page table in the system in megabytes is ___________

• 2
• 4
• 8
• 16

Question 45

Consider six memory partitions of size 200 KB, 400 KB, 600 KB, 500 KB, 300 KB, and 250 KB, where KB refers to kilobyte. These partitions need to be allotted to four processes of sizes 357 KB, 210 KB, 468 KB and 491 KB in that order. If the best fit algorithm is used, which partitions are NOT allotted to any process?

• 200 KB and 300 KB
• 200 KB and 250 KB
• 250 KB and 300 KB
• 300 KB and 400 KB

Question 46

A Computer system implements 8 kilobyte pages and a 32-bit physical address space. Each page table entry contains a valid bit, a dirty bit three permission bits, and the translation. If the maximum size of the page table of a process is 24 megabytes, the length of the virtual address supported by the system is _______________ bits

• 36

• 32

• 28

• 40

Question 47

Which one of the following is NOT shared by the threads of the same process?

• Stack
• Address Space
• File Descriptor Table
• Message Queue

Question 48

Consider a fully associative cache with 8 cache blocks (numbered 0-7) and the following sequence of memory block requests: 4, 3, 25, 8, 19, 6, 25, 8, 16, 35, 45, 22, 8, 3, 16, 25, 7 If LRU replacement policy is used, which cache block will have memory block 7?  

• 4
• 5
• 6
• 7

Question 49

The storage area of a disk has innermost diameter of 10 cm and outermost diameter of 20 cm. The maximum storage density of the disk is 1400bits/cm. The disk rotates at a speed of 4200 RPM. The main memory of a computer has 64-bit word length and 1µs cycle time. If cycle stealing is used for data transfer from the disk, the percentage of memory cycles stolen for transferring one word is  

• 0.5%
• 1%
• 5%
• 10%

Question 50

In a particular Unix OS, each data block is of size 1024 bytes, each node has 10 direct data block addresses and three additional addresses: one for single indirect block, one for double indirect block and one for triple indirect block. Also, each block can contain addresses for 128 blocks. Which one of the following is approximately the maximum size of a file in the file system?  

• 512 MB
• 2GB
• 8GB
• 16GB