Alternative Directory Schemes
The “bit vector directory” storage-costly
Consider improvements to Mblk*P cost
- Increase block size, cluster processors
- Just keep list of Processor Ids of sharers
- Need overflow scheme
- Five slots suffices
- Link the shared items together
- Home keeps the head of list
- List is doubly-linked
- New sharer adds self to head of list
- Obvious protocol suffices, but watch for races