Alternative Directory Schemes
The
bit vector directory is 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 probably suffice
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