Execution Pipeline

Question 1

What architecture uses the execution pipeline?

Answer 1

RISC

Question 1

What is the execution pipeline?

Answer 1

● Hardware optimization technique
● Allows the execution of instructions in
parallel.
● Used by RISC architectures

Question 2

How is an instruction executed?

Answer 2

● Fetch the next instruction
● Examine the opcode to determine the operands needed
● Fetch the operands
● Perform the specified operation
● Store the result in the indicated location

Question 3

How many operations can an N stage pipeline perform simultaneously?

Answer 3

N

Question 4

How long does each stage in a pipeline take?

Answer 4

One clock cycle

Question 5

What controls the execution pipeline?

Answer 5

The processor

Question 6

Generally, why does a pipe stall happen?

Answer 6

if the next instruction
depends on the result of the previous
instruction.

Question 7

What are some specific causes of pipe stalls?

Answer 7

● Access to RAM
● Call an instruction that takes a long time like multiplication, division, FP arithmetic
● Branch to a new location
● Call a function

Question 8

How can a programmer avoid pipe stalls in their program?

Answer 8

● Reordering instructions
● – Avoid introducing unnecessary branches
● – Delay references to result register(s)
● - Avoid Memory access