Virtual Memory

In optimal page replacement algorithm, information about all future page references is available to the operating system (OS). A modification of the optimal page replacement algorithm is as follows: The OS correctly pred...

Consider the following two-dimensional array D in the C programming language, which is stored in row-major order: int D[128] [128]; Demand paging is used for allocating memory and each physical page frame holds 512 eleme...

Consider a demand paging system with four page frames (initially empty) and LRU page replacement policy. For the following page reference string 7, 2, 7, 3, 2, 5, 3, 4, 6, 7, 7, 1, 5, 6, 1 the page fault rate, defined as...

Consider a paging system that uses a 1-level page table residing in main memory and a TLB for address translation. Each main memory access takes 100 ns and TLB lookup takes 20 ns. Each page transfer to/from the disk take...

Consider a process executing on an operating system that uses demand paging. The average time for a memory access in the system is $$M$$ units if the corresponding memory page is available in memory, and $$D$$ units if t...

In which one of the following page replacement algorithms it is possible for the page fault rate to increase even when the number of allocated frames increases?

Consider a main memory with five page frames and the following sequence of page references: 3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3. Which one of the following is true with respect to page replacement policies First...

A computer has twenty physical page frames which contain pages numbered $$101$$ through $$120.$$ Now a program accesses the pages numbered $$1, 2, …, 100$$ in that order, and repeats the access sequence THRICE . Which on...

A system uses $$3$$ page frames for storing process pages in main memory. It uses the Least Recently Used $$(LRU)$$ page replacement policy. Assume that all the page frames are initially empty. What is the total number o...

Assume that there are $$3$$ page frames which are initially empty. If the page reference string is $$1, 2, 3, 4, 2, 1, 5, 3, 2, 4, 6,$$ the number of page faults using the optimal replacement policy is______________.

Consider the virtual page reference string $$$1,2,3,2,4,1,3,2,4,1$$$ On a demand paged virtual memory system running on a computer system that has main memory size of $$3$$ page frames which are initially empty. Let $$LR...

A system uses FIFO policy for page replacement. It has $$4$$ pages frames with no pages loaded to begin with. The system first accesses $$100$$ distinct pages in some order and then accesses the same $$100$$ pages but no...

In which one of the following page replacement policies, Belady’s anomaly may occur?

Consider the virtual page reference string $$$1,2,3,2,4,1,3,2,4,1$$$ On a demand paged virtual memory system running on a computer system that has main memory size of $$3$$ page frames which are initially empty. Let $$LR...

A process has been allocated $$3$$ page frames. Assume that none of the pages of the process are available in the memory initially. The process makes the following sequence of page references (reference string): $$$1, 2,...

A process has been allocated $$3$$ page frames. Assume that none of the pages of the process are available in the memory initially. The process makes the following sequence of page references (reference string): $$$1, 2,...

A virtual memory system uses First In First Out (FIFO) page replacement policy and allocates a fixed number of frames to a process. Consider the following statements: $$P:$$ Increasing the number of page frames allocated...

A Computer system supports $$32$$-bit virtual addresses as well as $$32$$-bit physical addresses. Since the virtual address space is of the same size as the physical address space, the operating system designers decide t...

Increasing the $$RAM$$ of a computer typically improves performance because

The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by.

Which of the following is NOT an advantage of using shared, dynamically linked libraries as opposed to using statically linked libraries?

The optimal page replacement algorithm will select the page that.

Which of the following statements is false?

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

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.

Which of the following is/are advantage of virtual memory?

If an instruction takes $${\rm I}$$ microseconds and a page fault takes an additional $$j$$ microseconds, the effective instruction time if on the average a page fault occurs every $$k$$ instruction is:

Locality of reference implies that the page reference being made by a process

Dirty bit for a page in a page table

In a virtual memory system the address space specified by the address lines of the $$CPU$$ must be __________ than the physical memory size and _______ than the secondary storage size.

The address sequence generated by tracing a particular program executing in a pure demand paging system with $$100$$ records per page with $$1$$ free main memory frame is recorded as follows. What is the number of page f...

A memory page containing a heavily used variable that was initialized very early and is in constant use is removed when

The following page addresses, in the given sequence, were generated by a program: 1 2 3 4 1 3 5 2 1 5 4 3 2 3 This program is run on a demand paged virtual memory system, with main memory size equal to $$4$$ pages. Indic...

Let the page reference and the working set window be c c d b c e c e a d and 4, respectively. The initial working set at time $$t = 0$$ contains the pages {a, d, e}, where a was referenced at time $$t = 0, d$$ was refere...

Which page replacement policy sometimes leads to more page faults when size of memory is increased?

The total size of address space in a virtual memory systems is limited by

State whether the following statement TRUE or FALSE. The amount of virtual memory available is limited by the availability of secondary storage.

State whether the following statement TRUE or FALSE. The $$LRU$$ page-replacement policy may cause thrashing for some type of programs.

In a two -level virtual memory, the memory access time for main memory, $${t_M} = {10^{ - 8}}\sec $$ and the memory access time for the secondary memory, tag $$ = {10^{ - 3}}.$$ What must be the hit ratio, $$H$$ such tha...

Match the pairs in the following question. List - $${\rm I}$$ $$(A)$$$$\,\,\,\,$$ Virtual Memory $$(B)$$$$\,\,\,\,$$ Shared memory $$(C)$$$$\,\,\,\,$$ Look-ahead buffer $$(D)$$$$\,\,\,\,$$ Look-aside buffer List - $${\rm...