Question

Question: For the problems in this exercise, assume that there are no pipeline stalls and that the breakdown of executed instructions is as follows: add addi not beq lw sw 20% 20% 0% 25% 25% 10% 4.5.1 [10] In what fraction of all cycles is the data memory used? 4.5.2 [10] In what fraction of all cycles is the input of the sign-extend circuit needed? What is this circuit doing in cycles in which its input is not needed.

Short answer

4.5.1

The required fraction of the data memory used is 35%.

4.5.2

The required input fraction of the sign-extend circuit is 80%.

The resource for activation of it’s the usage sends to the control signal.

Step-by-step solution

Define the concept.

4.5.1

The required fraction of the data memory used is referred to as the sum of the breakdown of the executed instruction “lw” and the breakdown of the executed instruction “sw” instruction.

The required fraction = (the breakdown of the executed instruction “lw” + the breakdown of the executed instruction “sw” instruction) .

4.5.2

The required input fraction of the sign-extend circuit is known as the sum of the breakdown of the executed instruction “addi” , the breakdown of the executed instruction “beq” , the breakdown of the executed instruction “lw” and the breakdown of “sw”.

The required fraction = (the breakdown of the executed instruction “addi” + the breakdown of the executed instruction “beq” + the breakdown of the executed instruction “lw” + the breakdown of “sw”) .

Determine the calculation.

4.5.1

Given that,

Name of the executed instructions	The breakdown
add	20%
addi	20%
not	0%
beq	25%
lw	25%
sw	10%

The required fraction of the data memory used= (the breakdown of the executed instruction “lw” + the breakdown of the executed instruction “sw” instruction) =(25+10)%= 35%.

4.5.2

Given that,

Name of the executed instructions	The breakdown
add	20%
addi	20%
not	0%
beq	25%
lw	25%
sw	10%

The required input fraction of the sign-extend circuit = (the breakdown of the executed instruction “addi” + the breakdown of the executed instruction “beq” + the breakdown of the executed instruction “lw” + the breakdown of “sw”)

= (20+25+25+10)%=80%.

The resource for activation of it’s the usage sends to the control signal.

The operation is performed even in unnecessary areas, it is ignored because it is not used in cycles.