Two Processors Make Fetch&Add(V,1)
•Simultaneous requests collide in network
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
0 0
1 1
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
111
Fetch&Add(V)
Fetch&Add(V)
V
Fetch&Add increases potential for collisions
Hot spot