1. CSCE 212 Quiz 9a – 4/1/11 For the following questions, assume the clock cycle times given above and the following set of instructions: lw $5, -16($5) sw $5, -16($5) add $5, $5, $5 1.What is the total execution time of this instruction sequence without forwarding and with full forwarding? 2.What is the speed-up achieved by adding full forwarding to a pipeline that had no forwarding? * ALU instruction can forward a value to EX stage of next instruction. Without forwardingWith full forwarding* 200 ps250 ps

2. CSCE 212 Quiz 9a Answers First determine nops and total clock cycles. WithoutWithlw $5, -16($5)nop nopsw $5, -16($5) sw $5, -16($5)add $5, $5, $5 add $5, $5, $5 (7 + 2 clock cycles)(7 + 1 clock cycles)

3. CSCE 212 Quiz 9a Answers 1.What is the total execution time of this instruction sequence without forwarding and with full forwarding? Without(7 + 2) x 200ps = 1800ps With(7 + 1) x 250ps = 2000ps

4. CSCE 212 Quiz 9a Answers 2.What is the speed-up achieved by adding full forwarding to a pipeline that had no forwarding? 1800/2000 = 0.90 (actually a slowdown)