Week 11: Cache lookup, Replacement policies

Week 11: Cache lookup, Replacement policies

Method Description
Fully associative
Direct associative
Set associative


Page Coloring




Cache replacement policy

Policy Description
MIN 이상적인 알고리즘. '미래'의 memory access를 참고하여 cache eviction을 함
LRU Least Recently Used
LFU Least Frequently Used


Belady’s Anomaly: Cache size가 커졌는데 cache hit ratio는 줄어듦.

Belady's Anomaly

Belady’s Anomaly


Models for Application File I/O

•Explicit read/write system calls
–Data copied to user process using system call
–Application operates on data
–Data copied back to kernel using system call
•Memory-mapped files
–Open file as a memory segment
–Program uses load/store instructions on segment memory, implicitly operating on the file
–Page fault if portion of file is not yet in memory
–Kernel brings missing blocks into memory, restarts process


Advantages to Memory-mapped Files

•Programming simplicity, esp for large file
–Operate directly on file, instead of copy in/copy out
•Zero-copy I/O
–Data brought from disk directly into page frame
–Process can start working before all the pages are populated
•Interprocess communication
–Shared memory segment vs. temporary file


Demand Paging

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.