Cache coherence ppt

this ppt of cache coherence

1. BRAINWARE UNIVERSITY Name:-arendra singh Student code:-(BWU/BEC/19/027) Department:-b-tech(ECE) Semester:-5 THh Subject:-PCC-EC(502) COMPUTER ARCHITECTURE JDK SIR Topic:-cache Coherence

2.   cache coherence? In a single cpu system ,two copies of same data (one in cache and other in main memory) may become inconsistent Contents of cache and main memory can be altered by more than one device

3. Techniques For Cache coherence (single CPU) for avoiding Cache coherence write through:- when you update cache you have to update in main memory at same time(it takes lots of acces time due to overhead Write Block:- block of data can updated at time including block of main memory and cache memory Instruction cache:- in this the property of cache changed means:- till now data is store but we built in different way they can direcly store instruction

4. Cache coherence (in multiprocessor environment ) for avoiding Cache coherence 1)Sharing of writeable data 2) Process migration 3) i /o activity

5. p1 p2 X x p1 p2 p1 x x X` X` x x` p2 x 1 ) Sharing of writeable data Processors cache Shared memory Before update Write through Write block

6. p1 p2 X x p1 p2 p1 x x X` X` x x` p2 x 2 ) Process migration Processors cache Shared memory Before update Write through Write block

7. p1 p2 x p1 p2 p1 x x X` X` X` x p2 x 3) i /o activity Processors cache Shared memory Before update Write through Write block x x x i /o processor

8. To avoid Chache coherence we have two Types of solution   1. Software solution 2. Hardware solution

9. 1. Software solution     os keeps away from cache   1 Safe Period 2 Critical Period  

10. 2. Hardware solution       1)Snoopy Protocols 2)Directory Protocols

11. we have two Types of Protocols   1. Snoopy Protocols 2. Directory Protocols

12. 1. Snoopy Protocols   1 Write-invalidate 2 Write Update policy  

13. 2. Directory Protocols