19. Approximate LRU Implementation
This chapter delves into various page replacement algorithms used in memory management, highlighting the limitations of exact LRU and introducing approximate LRU methods such as reference bits and sampled LRU. It discusses the clock algorithm and second chance strategies while also addressing Belady's anomaly, which challenges conventional expectations regarding page fault occurrences with increased memory frames. The chapter emphasizes the importance of efficiently managing memory references to optimize system performance.
Enroll to start learning
You've not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Sections
Navigate through the learning materials and practice exercises.
What we have learnt
- Approximate LRU uses reference bits to manage memory more efficiently than exact LRU.
- The clock algorithm provides a second chance to recently accessed pages, improving replacement decisions.
- Belady's anomaly illustrates that increasing memory frames can lead to more page faults, contradicting intuitive expectations.
Key Concepts
- -- Approximate LRU
- A memory management strategy that uses reference bits to approximate the least recently used algorithm by tracking page usage within defined intervals.
- -- Clock Algorithm
- A page replacement algorithm that arranges pages in a circular list and gives recently accessed pages a second chance before replacing them.
- -- Belady's Anomaly
- An occurrence where increasing the number of page frames results in a higher number of page faults, which is counterintuitive as one would expect fewer faults with more frames.
Additional Learning Materials
Supplementary resources to enhance your learning experience.