datorteknik pipelining bild 1 acceleration how to improve speed? at what costs?

Datorteknik Pipelining bild 1

Acceleration

How to improve speed? At what costs?

Datorteknik Pipelining bild 2

T=Nq * CPI * Cycletime

Nq, Number of instructions CPI, Cycles Per Instruction Cycletime

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Single Cycle Design

CPI = 1 Cycletime = Long (Longest path)

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Multiple Cycle

1 < CPI < S Cycletime = Factor 1/S

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Pipelined design

CPI = 1, (Constant) Cycletime = Factor 1/S

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“THROUGHPUT”

The total amount of work done in a given time

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Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

INSTRUCTIONMEMORY

INSTRUCTION MEMORY STAGE (IM)

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Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

INSTRUCTION DECODE STAGE (DE)

Datorteknik Pipelining bild 9

Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

INSTRUCTION EXECUTE STAGE (EX)

Datorteknik Pipelining bild 10

Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

DATA MEMORY STAGE (DM)

DATA MEMORY

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Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

WRITEBACK STAGE (WB)

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Pipeline

5 stages, (IM, DE, EX, DM, WB) Writeback NOT in critical path Cut critical path by 4

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Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

CAN READ/WRITETHE SAME REG!

WRITEBACK STAGE (WB)

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Single Cycle

IM

Reg DM Reg

IM

Reg DM Reg

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IM

Reg DM Reg

4 Stage Pipe

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg

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A Program

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

0x3C sw $5 4($0)

$1 holds value 0x05

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IM

Reg DM Reg

4 Stage Pipe

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

0x3C sw $5 4($0)

Datorteknik Pipelining bild 18

IM

Reg DM Reg

Step 1

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

0x3C sw $5 4($0)

Datorteknik Pipelining bild 19

IM

Reg DM Reg

Step 2

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

0x3C sw $5 4($0)

Datorteknik Pipelining bild 20

IM

Reg DM Reg

Step 3

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

0x3C sw $5 4($0)

Datorteknik Pipelining bild 21

IM

Reg DM Reg

Step 4

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg0x3C sw $5 4($0)

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

Datorteknik Pipelining bild 22

IM

Reg DM Reg

Step 5

IM

Reg DM Reg

IM

Reg DM Reg

IM

Reg DM Reg0x3C sw $5 4($0)

0x30 sub $6 $0 $1

0x34 add $7 $0 $1

0x38 ori $2 $0 0xABCD

Datorteknik Pipelining bild 23

Branch

logic

Sgn/Ze

extend

Zero ext.

> 0x30 sub $6 $0 $1 0x34 add $7 $0 $1 0x38 ori $2 $0 0xABCD 0x3C sw $5 4($0)

ALU

A

B

31

0

4+

+

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Branch

logic

Sgn/Ze

extend

Zero ext.

0x30 sub $6 $0 $1> 0x34 add $7 $0 $1 0x38 ori $2 $0 0xABCD 0x3C sw $5 4($0)

ALU

A

B

31

0

4+

+

Datorteknik Pipelining bild 25

Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

0x30 sub $6 $0 $1 0x34 add $7 $0 $1> 0x38 ori $2 $0 0xABCD 0x3C sw $5 4($0)

Datorteknik Pipelining bild 26

Branch

logic

Sgn/Ze

extend

Zero ext.

ALU

A

B

31

0

4+

+

0x30 sub $6 $0 $1 0x34 add $7 $0 $1 0x38 ori $2 $0 0xABCD> 0x3C sw $5 4($0)