CREATE OWN LIBRARY
- Introduction: OS
- Booting Process
- Command Interpreter
- Dual mode of operation
- System Calls
- Difference between system call and library call
- Interrupt and Trap
- Introduction
- Scheduling Criteria, Terms and Concepts
- Different Type Scheduling Algorithms
- Longest Job First
- Longest Remaining Time First
- Highest Response Ratio Next (HRRN)
- Priority Scheduling
- Least Completed Next (LCN) Scheduling
- Multi-Level Queue Scheduling
- Multilevel Feedback Queue Scheduling
- Guaranteed Scheduling
- Fair Share Scheduling
- Lottery Scheduling
- Multi-Processor Scheduling
- Deadline Scheduling
- Rate-Monotonic Scheduling
- POSIX Real-Time Scheduling
- Priority Inversion
- Proportional Share Scheduling
- Comparison table of Scheduling Algorithm
- Algorithm Evaluation for Scheduling
- Important concept of MM
- Memory Representation as Address
- Memory layout for a Process
- Logical and Physical Address Space
- Necessity of Memory Management
- Introduction
- Concept of Non-contiguous memory allocation
- Basic concept of Paging
- Address Translation
- Process of Paging Method
- Calculation of Offset for paging
- Calculation of Logical Address Bit and number of Pages
- Calculation of Physical Address Bit and number of Frames
- Calculation of Page Table Size
- Organization of MMU
- Why Page size power of 2
- Paging Address Calculation: example1
- Paging Numeric Problem: Example2
- Paging Address Calculation: Example3
- Paging Address Calculation: Question1
- Some Important Question 2
- Paging Address Translation: Question3
- UGC NET Paging Question
- GATE Paging Question
- Number of information at Page Entry
- Exams Question on Page Entry Information
- Exam Question: Page Entry Information
- Calculates Page Table Entry Size
- Calculates Page Size
- Calculation of Optimal Page Size
- Question on Optimal Page Size
- Hashed Page Table with Example
- Inverted Page Table with Gate Question
- Question on Inverted Page Table
- Multi-Level Paging
- Multi-level paging: Example1
- Multi-level paging: Example2
- Allocation of Frames
- Subject Mock
Special feature of MRU
To see this topic please follow the previous chapter:
Some other page replacement algorithm
MRU replace the page which was just recently used in the frame of the main memory.
MRU performs best among all page replacement algorithms, for a special type of page references request sequence where the same sequence of same page references are coming repeated time (in a loop).
Example:
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9
Now, firstly we do this by FIFO and LRU then we calculate page fault by MRU. Now we compare page faults among FIFO, LRU, and MRU.
FIFO:
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9 and number of frame is 4.
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Number of page faults = 18
So, number of page references = number of page fault (all page requests are page fault). So, it is a thrashing.
LRU:
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9 and number of frame is 4.
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For this page reference, LRU performs the same as FIFO.
Number of page faults = 18
So, number of page references = number of page fault (all page requests are page fault). So, it is a thrashing.
MRU:
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9 and number of frame is 4.
.png)
Number of page faults = 10
So,
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9
Number of page faults using FIFO = 18 (Thrashing)
Number of page faults using LRU = 18 (Thrashing)
Number of page faults using MRU = 10
Important note (MRU benchmark Check):
As we know optimal page replacement algorithm always gives the best result (fewer page faults) and it is used as the benchmark.
So, for repeated page references optimal gives the same result as MRU.
Reversely we can say to check, MRU gives the best result or not (check benchmark), we should compare MRU with optimal page replacement algorithm.
Optimal
Page references: 4 5 6 7 8 9 4 5 6 7 8 9 4 5 6 7 8 9 and number of frame is 4.
.png)
Number of page faults = 10
So, here page faults of MRU and Optimal are the same.
