Basic Snoopy Protocols
- Write Invalidate Protocol:
- Multiple readers, single writer
- Write to shared data: an invalidate is sent to all caches which snoop and invalidate any copies
- Read Miss:
- Write-through: memory is always up-to-date
- Write-back: snoop in caches to find most recent copy
- Write Broadcast Protocol:
- Write to shared data: broadcast on bus, processors snoop, and update any copies
- Read miss: memory is always up-to-date
- Write serialization: bus serializes requests!
- Bus is single point of arbitration