1. Processor Consistency Exercise Is this example legal or illegal under processor consistency? Explain why or why not. If possible, put your explanation in a bulleted list. P1:P1:W(x) 3 P2:P2:W(x) 1 P3:P3:R(x) 1R(x) 3R(y) 0 P4:P4:W(y) 2

2. Processor Consistency Exercise (cont’d) Explain why the specific actions are needed under processor consistency CA P M P M P M P M Interconnection Network P 4 : W(y) 2 P 2 : W(x) 1 P1P1 P2P2 P3P3 P4P4 x=1 y=2

3. Processor Consistency Exercise (cont’d) Explain why the actions represented by the arrows are needed under processor consistency CA P M P M P M Interconnection Network CA P M y=2 x=1x=3 P1P1 P2P2 P3P3 P4P4 P 4 : W(y) 2 P 2 : W(x) 1 P 1 : W(x) 3

4. Processor Consistency Exercise (cont’d) What other values could be read for x? Explain. CA P M P M P M Interconnection Network CA P M y=2 x=1x=3 x=1 P1P1 P2P2 P3P3 P4P4 P 4 : W(y) 2 P 2 : W(x) 1 P 1 : W(x) 3 P 3 : R(x) 1

5. Processor Consistency Exercise (cont’d) Explain why the writes were “seen” in this order by P 3. CA P M P M P M Interconnection Network CA P M y=2 x=1x=3 P1P1 P2P2 P3P3 P4P4 P 4 : W(y) 2 P 2 : W(x) 1 P 1 : W(x) 3 P 3 : R(x) 1 P 3 : R(x) 3

6. Processor Consistency Exercise (cont’d) For what reason(s) was P 3 able to read an old value for y? CA P M P M P M P M Interconnection Network y=2x=1 x=3 y=0 P1P1 P2P2 P3P3 P4P4 y=2 P 4 : W(y) 2 P 2 : W(x) 1 P 1 : W(x) 3 P 3 : R(x) 1 P 3 : R(x) 3 P 3 : R(y) 0