OS Memory Management

Question 131

The principal of the locality of reference justifies the use of

• virtual memory
• interrupts
• main memory
• cache memory

Question 132

Virtual memory is

• Part of Main Memory only used for swapping
• A technique to allow a program, of size more than the size of main memory, to run
• Part of secondary storage used in program execution
• None of these

Question 133

Semaphores

• synchronize critical resources to prevent deadlock
• synchronize critical resources to prevent contention
• are used to do I/O
• are used for memory management

Question 134

The 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
• number of processes in memory
• physical memory size

Question 135

Consider a small 2-way set-associative cache memory, consisting of four blocks. For choosing the block to be replaced, use the least recently (LRU) scheme. The number of cache misses for the following sequence of block addresses is 8, 12, 0, 12, 8

• 2
• 3
• 4
• 5

Question 136

The size of the ROM required to build an 8-bit adder / subtractor with mode control, carry input, carry output and two’s complement overflow output is given as

• 2¹⁶ × 8
• 2 ¹⁸ × 10
• 2¹⁶ × 10
• 2 ¹⁸ × 8

Question 137

A specific editor has 200 K of program text, 15 K of initial stack, 50 K of initialized data, and 70 K of bootstrap code. If five editors are started simultaneously, how much physical memory is needed if shared text is used?

• 1135 K
• 335 K
• 1065 K
• 320 K

Question 138

For the implementation of a paging scheme, suppose the average process size be x bytes, the page size be y bytes, and each page entry requires z bytes. The optimum page size that minimizes the total overhead due to the page table and the internal fragmentation loss is given by

• x / 2
• xz / 2
• √(2xz)
• √(xz) / 2

Question 139

In a demand paging memory system, page table is held in registers. The time taken to service a page fault is 8 m.sec. if an empty frame is available or if the replaced page is not modified, and it takes 20 m.secs., if the replaced page is modified. What is the average access time to service a page fault assuming that the page to be replaced is modified 70 of the time?

• 11.6 m.sec.
• 16.4 m.sec.
• 28 m.sec.
• 14 m.sec.

Question 140

Which methods are utilized to control the access to an object in multi-threaded programming?

• Asynchronized methods
• Synchronized methods
• Serialized methods
• None of the above