CPU Cache Write Policies (Write Through, Write Back, Write Allocate, No Write Allocate)

CPU Cache Write Policies (Write Through, Write Back, Write Allocate, No Write Allocate)

Every time the CPU reads data from the cache, it is guaranteed to receive the correct, up-to-date data that corresponds to the requested address in main memory, regardless of whether it's a read hit or a read miss.
Writing to the cache introduces a challenge: when a block of data in the cache is modified, the main memory may still hold the outdated information at the accessed address. This is known as the cache coherence problem.
The main issue with stale data in memory is that other components in the system might access this outdated information, leading to incorrect results. To address this issue, caches use specific write policies and allocation policies suited to system needs.
In this video, I explain the 4 basic CPU cache write policies / allocation policies:
• Write-Through
• Write-Back
• Write-Allocate
• No-Write-Allocate

LINKS
📚 Computer Memory and Architecture E-Book Collection: https://buymeacoffee.com/bitlemonsoft...
📚 Inside the Core: How the CPU Works (E-Book): https://buymeacoffee.com/bitlemonsoft...
📚 Interrupts in Modern Computer Systems (E-Book): https://buymeacoffee.com/bitlemonsoft...
📚 The Anatomy of Virtual Memory (E-Book): https://buymeacoffee.com/bitlemonsoft...
📚 Beginner's Guide to CPU Caches (E-Book): https://buymeacoffee.com/bitlemonsoft...
❤ Support my work: https://buymeacoffee.com/bitlemonsoft...

SOURCES
•    • Write Back Cache | Write Through Cache | E...  
•    • Write Policy  
•    • Ep 077: Cache Write Policies, Flag Bits, a...  
•   / what-difference-between-write-allocate-no-...  
• https://www.geeksforgeeks.org/cache-w...
• https://www.geeksforgeeks.org/write-t...
• https://en.wikipedia.org/wiki/Cache_(...
• https://en.wikipedia.org/wiki/Cache_h...

TABLE OF CONTENTS
00:00 Introduction
00:55 Cache write policies overview
01:58 Write-through policy
02:30 Write-back policy
04:14 Write-allocate policy
05:21 No-write-allocate policy
06:03 Common policy combinations

#computerscience #cache #computerarchitecture #writepolicy #software