Dynamically Dynamically Reconfigurable Reconfigurable Architectures: Architectures: An OverviewAn Overview

Juanjo NogueraJuanjo Noguera

Dept. Computer Architecture (DAC-Dept. Computer Architecture (DAC-UPC)UPC)

jnoguera@ac.upc.esjnoguera@ac.upc.es

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IntroductionIntroduction Reconfigurable ComputingReconfigurable Computing

• Reconfigurable devices and systemsReconfigurable devices and systems• Reconfigurable Systems ClassificationReconfigurable Systems Classification• Reconfiguration MethodsReconfiguration Methods

Reconfigurable Instruction Set Reconfigurable Instruction Set ProcessorsProcessors• ASIP-based approachASIP-based approach• Coprocessor-based approachCoprocessor-based approach

ConclusionsConclusions

OutlineOutline

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Reconfigurable Computing (RC) is an Reconfigurable Computing (RC) is an emerging paradigm for digital emerging paradigm for digital systems designsystems design

Technology improvements have made Technology improvements have made possible new programmable logic possible new programmable logic devices (FPGAs, CPLDs)devices (FPGAs, CPLDs)

Objective of the talkObjective of the talk: Give an : Give an overview of RC concepts and overview of RC concepts and introduce the Reconfigurable introduce the Reconfigurable Instruction Set Processors. Instruction Set Processors.

IntroductionIntroduction

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Introduction (II)Introduction (II)

RC objectives:RC objectives: Specialization, performance, Specialization, performance, flexibilityflexibility

Basic idea: “Programmable Hardware”Basic idea: “Programmable Hardware”

SpecializationSpecialization

PerformancePerformance Power Power

consumptionconsumption

FlexibilityFlexibility ProgrammingProgramming

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Introduction (III)Introduction (III)

RC comparison versus other RC comparison versus other alternativesalternatives

Application SpecificSystems

General Purpose Systems

Cost

Performance

ReconfigurableComputing

Performance

Flexibility, Power

GPP

ASIC

DSP RC

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IntroductionIntroduction Reconfigurable ComputingReconfigurable Computing

• Reconfigurable devices and systemsReconfigurable devices and systems• Reconfigurable Systems ClassificationReconfigurable Systems Classification• Reconfiguration MethodsReconfiguration Methods

Reconfigurable Instruction Set Reconfigurable Instruction Set ProcessorsProcessors• ASIP-based approachASIP-based approach• Coprocessor-based approachCoprocessor-based approach

ConclusionsConclusions

OutlineOutline

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General device architectureGeneral device architecture

Reconfigurable DevicesReconfigurable DevicesR

econ

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ura

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Com

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Logic Bloc

InterconnectionStructure

I/O Bloc

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Routing strategiesRouting strategies

Reconfigurable Devices Reconfigurable Devices (II)(II)

Recon

fig

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Com

pu

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g

A B

C

A B

C

Continuous Routing Structured Routing

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SRAM based devices with infinite SRAM based devices with infinite number of reconfigurationsnumber of reconfigurations

Reconfigurable Devices Reconfigurable Devices (III)(III)

Recon

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Com

pu

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Configuration Bitstream110011101 ...

• App 1 -> Bitstream 1• App 2 -> Bitstream 2

• App n -> Bitstream n

Reconfigurable Device

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Rapid System (ASIC) PrototypingRapid System (ASIC) Prototyping

Reconfigurable Systems Reconfigurable Systems (I)(I)

Recon

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Com

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PLD PLDPLDCPU PLD

PLD

PLD PLD

PLD PLD

PLD

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Reconfigurable Systems Reconfigurable Systems ClassificationClassification

Reconfigurable Systems Reconfigurable Systems (II)(II)

Recon

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Com

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I/O PLD RAM

PLD

CPURAM

PLD

PLD RAM

(c)

(d)

(b)

(a)

HostComputer

SYSTEM BUS

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Reconfiguration Methods Reconfiguration Methods (I)(I)

Recon

fig

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Com

pu

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g Compile Time Reconfiguration (CTR)Compile Time Reconfiguration (CTR)• Device configuration is fixed during Device configuration is fixed during

application run time executionapplication run time execution

Run Time Reconfiguration (RTR)Run Time Reconfiguration (RTR)• Device configuration changes during Device configuration changes during

application run time executionapplication run time execution

RTR strategiesRTR strategies• Global RTRGlobal RTR• Partial RTRPartial RTR

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Global Run Time Reconfiguration Global Run Time Reconfiguration (Single context)(Single context)

Reconfiguration Methods Reconfiguration Methods (II)(II)

Recon

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Com

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#1

#2

#3

#4

Application

#1

Reconfiguration Contexts

Dynamically Reconfigurable Device

Reconfiguration

Execution

#2

Reconfiguration

ExecutionReconfiguration

#4

Execution

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Partial Run Time Reconfiguration Partial Run Time Reconfiguration (Multiple context)(Multiple context)

Reconfiguration Methods Reconfiguration Methods (III)(III)

Recon

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Com

pu

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g

#1

#2

#3

#4

Aplicació

Reconfiguration Contexts

Dynamically Reconfigurable Device

#4

#1

#3

Reconfiguration

#4

#1

#2

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Run-Time Reconfiguration Run-Time Reconfiguration ChallengesChallenges• Temporal PartitioningTemporal Partitioning• Context Scheduling (static)Context Scheduling (static)

Reconfiguration Latency OverheadReconfiguration Latency Overhead• Configuration Pre-fetchingConfiguration Pre-fetching• Configuration CachingConfiguration Caching• Configuration CompressionConfiguration Compression

Reconfiguration Methods Reconfiguration Methods (IV)(IV)

Recon

fig

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Com

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IntroductionIntroduction Reconfigurable ComputingReconfigurable Computing

• Reconfigurable devices and systemsReconfigurable devices and systems• Reconfigurable Systems ClassificationReconfigurable Systems Classification• Reconfiguration MethodsReconfiguration Methods

Reconfigurable Instruction Set Reconfigurable Instruction Set ProcessorsProcessors• ASIP-based approachASIP-based approach• Coprocessor-based approachCoprocessor-based approach

ConclusionsConclusions

OutlineOutline

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By including reconfigurability we By including reconfigurability we can increase flexibility with high can increase flexibility with high specializationspecialization

Introduction Introduction R

econ

fig

ura

ble

In

str

ucti

on

Set

Pro

cessors

Processor PLD

Reconfigurable Processor

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Coprocessor based approachCoprocessor based approach

ASIP based approachASIP based approach

Introduction (II)Introduction (II)R

econ

fig

ura

ble

In

str

ucti

on

Set

Pro

cessors

· · ·

Task 1 Task K

· · ·

Task K+1

Task N

Software Hardware

Task 1 Task 2 Task N

Software

Hardware

· · ·

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Typical example: CPU + PCI boardTypical example: CPU + PCI board• Altera ARC-PCIAltera ARC-PCI• Compaq PametteCompaq Pamette

System on Chip (SoC)System on Chip (SoC)• Altera´s Excalibur deviceAltera´s Excalibur device• Chameleon Systems, Inc.Chameleon Systems, Inc.

Coprocessor based approach Coprocessor based approach (I)(I)

Recon

fig

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ble

In

str

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on

Set

Pro

cessors

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Altera ARC-PCIAltera ARC-PCI

Coprocessor based approach Coprocessor based approach (II)(II)

Recon

fig

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ble

In

str

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on

Set

Pro

cessors

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Compaq PametteCompaq Pamette

Coprocessor based approach Coprocessor based approach (III)(III)

Recon

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ble

In

str

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on

Set

Pro

cessors

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Altera´s Excalibur deviceAltera´s Excalibur device• Embedded Processor: ARM, MIPS or Embedded Processor: ARM, MIPS or

NIOS NIOS

Coprocessor based approach Coprocessor based approach (IV)(IV)

Recon

fig

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ble

In

str

ucti

on

Set

Pro

cessors

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Chameleon Systems, Inc.Chameleon Systems, Inc.

Coprocessor based approach Coprocessor based approach (V)(V)

Recon

fig

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In

str

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on

Set

Pro

cessors

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Reconfigurable unit within CPUReconfigurable unit within CPU

ASIP based approach (I)ASIP based approach (I)R

econ

fig

ura

ble

In

str

ucti

on

Set

Pro

cessors

Fetch

Decode

Issue

IntegerUnit

FPUnit

BranchUnit

LD/STUnit

ReconfigurableUnit

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Challenge: CAD toolsChallenge: CAD tools

ASIP based approach (II)ASIP based approach (II)R

econ

fig

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ble

In

str

ucti

on

Set

Pro

cessors

C Code

Compiler

AssemblyCode

InstructionDescription

(Configuration bits)

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ASIP based approach (III)ASIP based approach (III)R

econ

fig

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ble

In

str

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on

Set

Pro

cessors

C Parsing

Optimizations

Inst. Identification

Inst. Selection

Config. Scheduling

Code Generation

C Code

Assembly Code

HardwareGeneration

Configuration bits

HardwareEstimator

Compiler Structure

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Example: Philips CinCISe Example: Philips CinCISe ArchitectureArchitecture

ASIP based approach (II)ASIP based approach (II)R

econ

fig

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ble

In

str

ucti

on

Set

Pro

cessors

En

cod

ed

In

str

ucti

on

Word

RegisterFile A

LU

RFU

MU

X

5

5

5

4

32

32

32

32

32

32

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Application example: DES & A5 Application example: DES & A5 encryptation algorithmsencryptation algorithms

ASIP based approach (III)ASIP based approach (III)R

econ

fig

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In

str

ucti

on

Set

Pro

cessors

27 26 25 23 22 30

7 6 5 4 3 2

27 26 25 22

XOR

srl $13, $2, 20andi $25, $13, 1srl $14, $2, 21andi $24, $14, 6or $15, $25, $24srl $13, $2, 22andi $14, $13, 56or $25, $15, $14sll $24, $25, 2

srl $24, $5, 18srl $25, $5, 17xor $8, $24, $25srl $9, $5, 16xor $10, $8, $9srl $11, $5, 13xor $12, $10, $11andi $13, $12, 1

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Reconfigurable Computing is an Reconfigurable Computing is an emerging and interesting computing emerging and interesting computing paradigmparadigm

RC devices and architectures are RC devices and architectures are becoming a realitybecoming a reality

There is a big challenge is High-level There is a big challenge is High-level synthesis (CAD) toolssynthesis (CAD) tools

ConclusionsConclusions

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What is the future ??What is the future ??

Conclusions (II)Conclusions (II)

Flexibility,Power

Performance

GPP

ASIC

DSP RC

RC

??

RC