Explain the reasoning behind the use of the LRU algorithm for virtual memory page replacement and file system buffer caches
The reasoning behind the use of the LRU algorithm for virtual memory page replacement and file system buffer caches are given below:
1. Practically Implementable :
The LRU uses the replacement of the old reference pages which are not recently referred.
It uses the stack for storing the page's reference in the memory.
2. Space Efficiency :
The LRU uses the doubly linked of storing the reference of the pages.This leads to the storing of the pages in a continuous manner.
This increases flexibility in storing the page reference.
Explain the reasoning behind the use of the LRU algorithm for virtual memory page replacement and...
As described in 5.7, virtual memory uses a page table to track the mapping of virtual addresses to the physical addresses. This exercise shows how this table must be updated as addresses are accessed. The following data constitutes a stream of virtual addresses as seen on a system. Assume 4 KiB pages, a 4-entry fully associative TLB, and true LRU replacement. If pages must be brought in from disk, increment the next largest page number. 4669, 2227, 13916, 34587, 48870,...
Implement the frame replacement algorithm for virtual memory Assume a computer system have 10 memory frames available inside the physical memory and is required to execute a process containing 20 pages. Assume a process P has been executed in the system and produced a sequence of 40 page demands as follows: Page demands trace of process P Demand 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 cont. Page...
Your system has 6 frames with 4 byte pages, and you use LRU for page replacement. Consider the following string of memory accesses (shown in decimal): 43, 41, 42, 13, 23, 22, 13, 42, 51, 61, 23, 21, 73, 42, 13, 21 How many page faults?
4 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 (GATE CS 2001) a) Always decrease the number of page faults b) Always increase the number of page faults c) Some times increase the number of page faults d) Never affect the number of page faults
Problem 6 (13 points) The page table below is for a system with 16-bit virtual as well as physical addresses and with 4,096-byte pages. The reference bit is set to 1 when the page has been referenced. Periodically, a thread zeroes out all values of the reference bit. A dash for a page frame indicates the page is not in memory. The LRll pagg-replacement algorithm is used. The numbers are given in decimal Page Frame eferepceit 14 10 13 15...
Problem 6 (13 points) The page table below is for a system with 16-bit virtual as well as physical addresses and with 4,096-byte pages. The reference bit is set to 1 when the page has been referenced. Periodically, a thread zeroes out all values of the reference bit. A dash for a page frame indicates the page is not in memory. The LRll pagg-replacement algorithm is used. The numbers are given in decimal Page Frame eferepceit 14 10 13 15...
3. Virtual Memory (20 points) An ISA supports an 8 bit, byte-addressable virtual address space. The corresponding physical memory has only 256 bytes. Each page contains 32 bytes. A simple, one-level translation scheme is used and the page table resides in physical memory. The initial contents of the frames of physical memory are shown below. VALUE address size 8 bit byte addressable each byte of addressing type memory has its own address 32 B page size physical memory size 256...
For the following reference string apply the FIFO page replacement algorithm. For the following reference string apply the OPT page replacement algorithm. For the following reference string apply the LRU page replacement algorithm. For the following reference string apply the LFU page replacement algorithm.
1. A page fault is (check all that apply)... a) In the context of virtual memory, it is caused by an access to a virtual memory address that has yet to be mapped to physical memory. b) In the context of exceptions, when a page from the second level cache has to be loaded into the translation look-aside buffer. c) none of these d) In the context of virtual memory, it is caused by a miss in the page table....
Which of the following about virtual memory is not true? A) Virtual memory needs paging hardware B)Virtual Memory uses storage device to extend the physical main memory C)The optimal replacement strategy is the most practical strategy D)Multiple process can share pages What should we do when having a page fault (Multiple answers)? A)Skip the machine instruction causing the page fault. B)Update the page table after loading the missing page C) Switch to a process that does not have page faults...