Blockers are responsible for blocking {TAIL ~ new request} for a cache line until an outstanding request for {HEAD ~ that cache line} has been serviced 
Blockers are responsible for blocking { TAIL ~ new request } for a cache line until an outstanding request for { HEAD ~ that cache line } has been serviced
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH