OS Memory Management

Question 121

Dynamic address translation

• is part of the operating system paging algorithm
• is useless when swapping is used
• is the hardware necessary to implement paging
• storage pages at a specific location on disk

Question 122

Thrashing

• always occurs on large computers
• is a natural consequence of virtual memory systems
• can always be avoided by swapping
• can be caused by poor paging algorithms

Question 123

Dirty bit for a page in a page table

• helps avoid unnecessary writes on a paging device
• helps maintain LRU information
• allows only read on a page
• None of the above

Question 124

Checkpointing a job

• allows it to be completed successfully
• allows it to continue executing later
• prepares it for finishing
• occurs only when there is an error in it

Question 125

Overlaying

• requires use of a loader
• allows larger programs, but requires more effort
• is most used on large computers
• is transparent to the user

Question 126

A critical section is a program segment

• which should run in a certain amount of time
• which avoids deadlocks
• where shared resources are accessed
• which must be enclosed by a pair of semaphore operations P and V

Question 127

Consider a logical address space of 8 pages of 1024 words mapped into memory of 32 frames. How many bits are there in the logical address?

• 13 bits
• 15 bits
• 14 bits
• 12 bits

Question 128

The page replacement algorithm which gives the lowest page fault rate is

• LRU
• FIFO
• Optimal page replacement
• Second chance algorithm

Question 129

What is the most appropriate function of Memory Management Unit (MMU)?

• It is an associative memory to store TLB
• It is a technique of supporting multiprogramming by creating dynamic partitions
• It is a chip to map virtual address to physical address
• It is an algorithm to allocate and deallocate main memory to a process

Question 130

The term ‘aging’ refers to

• booting up the priority of the process in multi-level of queue without feedback.
• keeping track of the following a page has been in memory for the purpose of LRU replacement
• letting job reside in memory for a certain amount of time so that the number of pages required can be estimated accurately.
• gradually increasing the priority of jobs that wait in the system for a long time to remedy infinite blocking