Question

1. Data forwarding. Can you please mark which lines in the figure are for data forwarding? Does data forwarding solve all data hazards in the figure?

Question 3: pipeline implementation a. Data forwarding. Can you please mark which lines in the figure are for data forwarding? Does data forwarding solve all data hazards in the figure? Time (in clock cycles) CC 1 CC 2 CC 4 CC5 сс 6 Program execution order (in instructions) LD R4, O(R1) SD R4,12(R1) ole 01

Answer 1

Time (in clock cycles) CC1 CC 4 CC5 CC6 LDR4, ORI) SO 14.12(1)

Solution to question 3 :-The Dark black lines in the figure below shows all the data forwarding lines .

Yes , this figure solve all data hazards problems because in the question three instructions are given which are decribed as follows:-

Definition:-

Data hazards occur when the pipeline changes the order of read /write access to the operands that is different from the normal execution sequence . Basically hazards are the delay in the pipeline due to the dependency problem .

There are three types of data hazards which are as follows :-

1. RAW Hazard ( Read after write hazard also known as true data dependency ) – It is created when instruction ‘J’ tries to read the data before instruction ‘I’ writes it .

2. WAR Hazard ( Write after read hazard also known as anti data dependency )- – It is created when instruction ‘J’ tries to write the data before instruction ‘I’ reads it .

3.WAW Hazard ( Write after write hazard also known as output data dependency ) – It is created when instruction ‘J’ tries to write the data before instruction ‘I’ writes it .

1. DADD R1 , R2 , R3     ( In this instruction three registers present R1, R2 , R3 . Data is present in R2 and      R3,on that data addition is performed . after that result copied in R1)

2. LD R4 , 0(R1)    ( this is load instruction , in this instruction dependency is present because of R1 that is R1 is reading before R1 written in the 1^st instruction so it is true data dependency . so data forwarding should take place because of data hazards.[RAW Hazard present ]

3. SD R4, 12(R1)    ( this instruction also dependent on the above two instructions because of R1( anti data dependency) and R4( output data dependency ) . So data forwarding should take place )

Time (in clock cycles) CC1 CC 4 CC5 CC6 LDR4, ORI) SO 14.12(1)