configurable, reconfigurable, and run-time reconfigurable computing

Configurable, reconfigurable, and run-

time reconfigurable computing

Outline

1. Introduction– Configurable– Reconfigurable– Run-time reconfigurable

2. Motivating example

3. Tools

4. Software compilers for configurable/reconfigurable systems

5. Multiprocessor complications

Modular Design of Configurable Multiprocessor Systems

Introduction


http://en.wikipedia.org/wiki/Knapsack_problem

Which boxes should be chosen to maximize the amount of money while still keeping the overall weight under 15 kg? A multi dimensional problem could consider the density or dimensions of the boxes, the latter a typical packing problem.

(The solution in this case is to choose all of the boxes besides the green one.)

Example of a one-dimensional (constraint) knapsack problem:

http://en.wikipedia.org/wiki/Packing_problem

Configuration

• Configurable solution:

1. Investigate the best set of boxes to take

2. Take them

3. No more thinking about boxes

• REconfigurable solution:

1. Investigate the best set of boxes to take

2. Take them for a long time

3. Stop what I’m doing and change everything in my backpack

• RUN TIME reconfigurable solution:

1. While walking, take the boxes I need and switch for the boxes I don’t need right now. This cost me some time to reconfigure the items in my backpack while walking.


Typical system design flowPower? Area?

Speed?

How can I quickly explore the design architecture and validate it early?

Which CPU?

Which device?Functionality?

Cost?

What are the partition trade off’s & how do I

verify them?

HW

SW

Spec

Project Specification

HDLsHW

ready

C/ C++

Codesign environment

Software-compiled system design flowPower? Area?

Speed?

Which CPU?

Which device?Functionality?

Cost?

What are the partition trade off’s & how do I

verify them?

Project Specification

Design & VerifySpecify & Verify

DS

M

Spec

HW

Compile & Verify

SystemC, Handel-C

C/ C++SWP

AL

DS

M

DS

M

DS

M

DS

M

How can I quickly explore the design architecture and validate it early?

What is the essential design question?

• MAIN QUESTION: How do we make practical systems (large) and meet time-to-market window (small)?

• ANSWER: Comprehensive co-design tools


Motivating Example

Motivating Example

• Congratulations! You are making a cellular phone.• There are many design constraints:

– Finite chip area– Finite power consumption– Finite memory (registers, cache, RAM, disk)– Real-time requirements for tasks

• There are many features:– Camera– Phonebook– Encryption/decryption– DSP– …


How do we do co-design for this project?

• We must make software and hardware for our beloved phone.• Which software segments should be implemented in hardware?• Do we add one more processor and bus connection, or dedicate

that area to a custom instruction?• We are OPTIMIZING• This is decision problem is also known as the “Knapsack

problem” and sometime the “assignment algorithm”, and computers can solve this faster than humans, given a complete and formal problem specification.


Real Configurable System Tools

• System level co-design fromspecification to direct implementation

– Profiling– Partitioning & trade-off analysis– Co-verification & co-simulation– Higher-level language (HLL) synthesis

direct to EDIF or RTL

• Software-compiled system design– Best time-to-market– Fastest simulation times … VERY FAST– HW/ SW partitioning solution– Seamless HW & SW verification– Reduces cost, risk & time of design– Best QoR & Quality of Design

Celoxica



Dimond 2004



CoWare Processor Designer



Tensilica

Tradeoffs


Tensilica

Tradeoffs


Configurable processors




From register file to configurable block



Stall for reconfigurationOr maybestall during execution



Not realistic

Techniques

• Many techniques for finding what to implement as hardware:– Atasu et al. (DAC 03, CODES 05)– Biswas et al. (DATE 05), Cong et al. (FPGA 04)– Clark et al. (MICRO 03, HOT CHIPS 04)– Goodwin and Petkov (CASES 03)– Sun et al. (ICCAD 03), Yu et al. (CASES 04)– Many more…

• This is an NP-hard problem equivalent to the “largest common sub-graph identification” problem


Software compilers for configurable/reconfigurable

systems

What do we want from our compiler?

• Make it easy to:– Add instructions to my processor model– Check if my model will meet my requirements (simulation/

profiling)– Optimize the generated code for small size and fast speed– Compile code on my PC to run on my phone (retargetable)

• Hide the details of anything I don’t care about:– Break the compiler into frond end, middle part, and a

backend


What toys do we need?

• Compiler (front-middle-backend), debugger, simulator, profiler, assembler, linker, operating system, FPGA


What are some common compilers?

• GCC (Java, Ada, C, C++, has open-MP, popular, optimizing)• LCC (Small code size)• Trimaran• MIMOLA• RECORD• CoSy• LLVM


Multiprocessor complications


Configurable Interconnect Design Flow

Graphical User Interface

GenerateSave

API

UserrequirementsM

SSystem

Generator

System CreatorInterconnection

system

VHDL Docs


WISHBONE Datasheet

• WISHBONE specification requires that each component has a datasheet


Example from WISHBONE B.3

Network Specification


Shared Bus

PE1Add 010

PE2Add 011

Mem AAdd 111

Mem BAdd 001

Shared Bus

PE3Add 010

PE4Add 011

Mem CAdd 111

Mem DAdd 001

1 0 1 0

DataFlow2DataFlow1

PE5

DataFlow1 DataFlow2DataFlow2DataFlow1

LED 13

PE1 Load A, invert on cycle 1PE2 load BPE1 send APE2 add A+BPE2 send A+B to PE5

PE3 Load C, invert on cycle 1PE4 load DPE3 send CPE4 add C+DPE4 send C+D to PE5

PE5 compare A+B & C+D

If A+B < C+D à LEDG0If A+B = C+D à LEDG1If A+B > C+D à LEDG2

Example Interconnect


P3P6P4 P5

M0 M0 M0

P7

M0

P8

M0

Shared Bus Crossbar

M3M2M1M0

S1S0

S0

MEM9

S1

MEM11

S0 S0

MEM10

S1S0

M0 M1

First;Add 1 to M9

Second;Add 1 to M9

Third;Add 1 to M9

Fourth;Add 1 to M9;

Saves number in M11

Checking when data in M11 not equal to Zero;

When data != 0 then adds 1 to it and saves number

in M10

Checking when data in M10 not equal to Zero;

When data != 0 then adds 1 to it and saves number

in M10

1 2

Life looks simple at first


But life is complicated


Questions?

Thank You

configurable, reconfigurable, and run-time reconfigurable computing

Documents

design constraints

essential design question

problemwhich boxes

best set of boxes

decision problem

diskrealtime requirements

formal problem specification

multi dimensional problem