P3 Writes a Changing It To 5 Part I
•On a write access fault at Px, local controller checks and finds it remote; finds the home
•Controller sends request to home node for blk
•Home controller looks up directory entry of blk
–Dirty bit OFF, the home has a clean
copy
•Home node sends data to Px w/presence vector
•Home controller clears directory, sets
xth bit and dirty ON
•Px controller sends invalidation request to all
nodes listed
P1
a:V:4
Controller
a:4
10001
P2
$
Controller
P3
Stalled
a:V:4
Controller
P0
a:V:4
Controller
Interconnection
Network
Msg: P3 to P1, Write a
Msg: P1 to P3, a:01101
Msg: P3 to P0, Invalid a
Msg: P3 to P1, Invalid a