b) What do you understand by branch prediction and explain correlating branch predictor?
Part B (Each Question Carries 9 Marks)

4. a) Complete the following table using Tomasutoes algorithm with reservation stations and Reorder Buffer,

i) Assume the following information about functional units,

Functional unit Cycles in Ex
type

Integer Mul 2

Integer Div 10

Integer Add

ii) Assume processor can issue into the reservation stations and reorder buffer only one instruction per cycle.

iii) Assume you have unlimited reservation stations, functional units, reorder buffer entries and CDB .iv) The
Functional units are not pipelined.

v) Fill in the cyple numbers in each pipeline stage for each instruction. For each instruction indicate where its
source operand's are read from (use RF for register file, CDB for common data bus and ROB for
Reorder Buffer).

vi) As6 for simplicity when an operand is waiting for an execution unit's result just indicate as waiting on
COB, instead of the number of the execution unit. http:/*'mxww.ktuonline.com vii) An instruction

waiting for data on CDB can move to its EX stage in the cycle after the CDB broadcast.

viii) Assume that integer instructions also follow Tomasuloes algorithm so the result from the integer functlonal
unit is also broadcast on CDB and forwarded to dependent instructions through COB.

Some of the entries for the instructions and the issue stage are already filled in.

Instructions ௬ இ Operand 1 Operand2 | ‏لاع‎ WB Comm
issued source source
2 | |

2 2

COB
| 3
| தி
்‌ 00
a
7 7