In this section of Operating System Memory Management.it contain Virtual Memory – Demand Paging-2 MCQs (Multiple Choice Questions Answers).All the MCQs (Multiple Choice Question Answers) requires in detail reading of Operating System subject as the hardness level of MCQs have been kept to advanced level.
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1. Page replacement becomes necessary when
- Page faults occur and there are no free page frames in the memory.
- Page faults occur and there are free page frames in the memory.
- Page faults would arise if the replaced page is referenced again.
- It is important to replace a page that is not likely to be referenced again in the immediate future.
- 1 only
- 1 and 3 only
- 1 , 2 and 4 only
- 1,3 and 4 only
2. Which of the following statements stands true for locality of reference in page replacement and handling page faults?
- It states that the physical addresses used by a process in any short interval of time during its operation tend to be bunched together in certain portion of its logical address space.
- It states that the logical addresses used by a process in any short interval of time during its operation tend to be bunched together in certain portion of its logical address space.
- It states that the physical addresses used by a process in any short interval of time during its operation tend to be bunched together in certain portion of its physical address space.
- It states that the logical addresses used by a process in any Long interval of time during its operation tend to be bunched differently in certain portion of its logical address space.
Process exhibits this behavior for two reasons; Execution of instructions in the process is mostly sequential in nature, because only 10-20 percent of instructions executed by a process are branch instructions.
3. The computer exploits the law of locality to ensure__________
- More page faults and high hit ratio in cache
- Fewer page faults and high hit ratio in the disk
- High hit ratio in the cache and fewer page faults
- None of the above.
4. How much memory should the virtual memory manager allocates to a process depends on which of the below factors?
- An overcommitment of memory to a process implies a low page fault rate for the process;hence it ensures good process performance.
- An undercommitment of memory to a process causes a high page fault rate,which would lead to poor performance of the process
- In An overcommitment of memory to a process however if a smaller number of processes would fit in memory which would causes CPU idling and poor system performance.
- All of the above.
5. When a process is operating in low memory allocation and has high page fault rate, this process spends a lot its time in the ____________
- Active state
- Pending State
- Blocked State
- Ready State
6. A situation where All the processes in the system operate in the region of high page fault rates, the CPU would be engaged in performing page traffic and process switching most of the time and throughput would be poor Called________
- Swapping
- Switching
- Paging
- Thrashing
7. A situation where too few processes exists in memory or all process in memory perform I/O operations frequently is called _______
- Swapping
- Context Switching
- Paging
- Thrashing
this situation is different in that all processes make poor progress because of high page fault rates.
8. Which of the following Statement stands true for the optimal page size of process?
It determines______
- the number of bits required to represent the byte number in a page
- Memory wastage due to internal fragmentation
- Size of page table for a process
- Page Fault rates when a fixed amount of memory is allocated to a process
- 1 Only
- 1 and 2 only
- 1,2 and 3 only
- All of the above.
9. Consider a process Pi of size z A page size of s bytes implies that the process has an n pages, where ______
- n = [z/s]
- n = [s/z]
- n = [zs]
- n = [z - s]
10. Consider a process Pi of size z bytes. A page size of s bytes implies that the process has an n pages, where n = [z/s] .An Average internal fragmentation is __________
- s bytes
- s/2 bytes
- 1/s bytes
- 2s bytes
11. The MMU contains special register called__________ to point to the start of a page table
- Page address resistor (PAR)
- Page Frame Address resistor (PFAR)
- Page table Address resistor (PTAR)
- Page table size Resistor (PTSR)
for a logical address (pi , bi) , the MMU computes <PTAR> + pi × lPT_entry to obtain the address of the page table entry of page pi, where lPT_entry is the length of the page table entry and <PTAR> denotes the content of the PTAR. The PTAR has to be loaded with the correct address when a process is scheduled.
12. Kernel can store the address of the page table of a process in its _________
- Relocation Register
- Process Control block
- Stack
- Heap
13. The MMU provides a special register called the ______ if a process tries to access a nonexistent page, or exceeds its access privileges while accessing a page. and a memory protection interrupt raised.
- relocation register
- page table address register
- page table size register
- Process control block
14. Which of the following is the function of paging hardware
- Memory protection
- Efficient address translation
- Page replacement support
- All of the above.
15. The ________ is a small and fast associative memory that is used to eliminate the reference to the page table.
- PCB
- VM Manager
- Free frame list
- TLB
TLB translation look-aside buffer is a small and fast associative memory that speeds up address translation
16. The TLB contains entries of the form ________ for a few recently accessed pages of a program that are in memory.
- Valid bit, page frame #, Prot info
- Page # , Page frame # , Prot info
- Valid bit, page frame #, Page #
- Page # , Page frame # , Valid bit
During address translation of a logical address (pi,bi) , the TLB hardware searches for an entry of page pi , if an entry is found, the page frame # from the entry is used to complete address translation for the logical address (pi,bi).
17. A probability that a page exists in memory is known as _______
- TLB hit ratio
- TLB miss ratio
- Memory hit ratio
- Memory miss ratio
18. A probability that a page exists in TLB is known as _______
- TLB hit ratio
- TLB miss ratio
- Memory hit ratio
- Memory miss ratio
19. When TLB is used for a address translation, effective memory access time is ______ Where Pr1 = Probability that page exists in memory Pr2 = Probability that page exists in TLB tmem = memory access time tTLB = access time of TLB tpfh = time overhead of page fault handling
- Pr2 × (tTLB + tmem ) + (Pr1 - Pr2) × (tTLB + 2 × tmem) - (1 - Pr1) × (tTLB + tmem + tpfh + tTLB + 2 × tmem)
- Pr2 × (tTLB + tmem ) - (Pr1 - Pr2) × (tTLB + 2 × tmem) - (1 - Pr1) × (tTLB + tmem + tpfh + tTLB + 2 × tmem)
- Pr2 × (tTLB + tmem ) + (Pr1 - Pr2) × (tTLB + 2 × tmem) + (1 - Pr1) × (tTLB + tmem + tpfh + tTLB + 2 × tmem)
- Pr2 × (tTLB - tmem ) + (Pr1 + Pr2) × (tTLB - 2 × tmem) + (1 - Pr1) × (tTLB - tmem + tpfh + tTLB + 2 × tmem)
20. Which of the following is used to reduce the size of memory committed to page tables?
- Inverted page table
- Single level page table
- Multilevel page table
- Both a and c.
21. In which of the following the page table of a process is itself is paged; the entire page table therefore does not need to exist in memory at any time?
- Inverted page table
- Single level page table
- Multilevel page table
- Multiprogramming page table
A higher level page table is used to access pages of the page table. if the higher level page table is large, it could itself be paged and so on. In this organization, the page table entry of a page has to be accessed through relevant entries of the higher level page tables.
22. In which of the following the size of page table is governed by the size of memory, so it is independent of the number and size of processes. However information about a page cannot be accessed directly as in page table?
- Inverted page table
- Single level page table
- Multilevel page table
- Multiprogramming page table
the Inverted page table (IPT) has one entry for each page frame in memory that indicates which page, if any occupies the page frame; the table got this name because the information in it is the ‘inverse’ of the information in a page table.
