Efficient Embedded Runtime Systems through Optimization of Port Communication

Software Engineering InstituteCarnegie Mellon UniversityPittsburgh, PA 15213

Peter H FeilerApril 2, 2008

2Port Communication OptimizationFeiler, April 2008

Outline

The problem

Buffer lifespan model

Buffer optimization considerations

Property preserving transformation

Shared Variable Communication

Navigation Sensor

Processing

Integrated Navigation

Guidance Processing

Flight PlanProcessing

Aircraft Performance Calculation

From other

Partitions

Periodic I/O20Hz

To other

Partitions

Shared data area

Data flow determined by execution order of

write & read

Preemption and concurrency affect

read/write order

Non-Deterministic Sampling of Data Stream

Example: Downsampling

• Desired sampling pattern 2X: n, n+2, n+4 (2,2,2,…)

• Worst-case sampling pattern: n, n+1, n+4 (1,3,…)

Timeline

Thread NavSensorProcessing

Thread IntegratedNavigation

NavSensor Processing

Integrated Navigation

20Hz 10Hz

Port-based AADL Model

Navigation Sensor

Processing

Integrated Navigation Guidance

Processing

Flight PlanProcessing

Aircraft Performance Calculation

10Hz 20Hz

Partitions

Fuel Flow

Guidance

sensor

Nav signal

FP data

Performance

dataNav sensor

Nav data

FP data

Periodic I/O20Hz

Immediate and delayed data port connections for

deterministic sampling

Input-compute-output AADL thread semantics

Outline

The problem

General Unqueued Port Buffer Model

Producer

Consumer/Producer

Receive

Consumer

Receive

MP: producer copy

MS: send copy

MR: receive copy

MC: consumer copy

• Send/receive with or without copy

• Transfer with or without copy

• Processing with or without copy

Message Streaming Lifespan Model

MPiProducer task

Send buffer

Receive

Consumer task MCi+1

MRi+1Receive buffer

TP, Mi+1DP, Mi+1

TC, MiDC, Mi

Message Lifespan Properties

Message operation ordering condition

SMi < XMi

MP bounded by producer dispatches

TP, Mi BMPi

EMPi = SMi

TP, Mi+1

MC bounded by consumer dispatches

TC, Mi RMi

= BMCi EMCi

TC, Mi+1

MS bounded by sends and transfer

SMi = BMSi

< SMi+1

MR bounded by transfers and receive

BMRi EMRi

= R***Mi

< XMi+1

* Completion of transfer

** Start of transfer

*** Latest of multiple receivers

Outline

The problem

Sequential Task Execution

TP ; TC

Collapse to single buffer

Overlapping Message Instances

Overlapping message instance lifespan

Send, transfer, or receive as copy operation

Copy message between 2 buffers before BMPi+1

after EMCi-1

Application-based Send and Receive (ASR)

ASR/IMT

P - P C - C non-deterministic S/R

TP P S P DP

TC C R C DC

: actual execution start time

: actual completion time

Buffer Optimization Considerations

Send and receive execution• As part of application (ASR)

• As part of task dispatch/completion (DSR)

Task execution order• Concurrent: C | P

• Atomic non-deterministic: C ≠ P

• Ordered: C ; P or P ; C

Periodic & aperiodic task dispatch

Message transfer• Immediate to consumer (IMT)

• Direct to delayed consumer (DMT)

• Period-delayed to consumer (PMT)

Consumer Before Producer

C ; P consumer before producer: C,j P,j

• Non-preemption: P,j - P,j C,j - C,j =

• Deterministic S/R for ASR & DSR

• ASR

• Sj-1 < Tj < Rj < Sj < Tj+1 : Sj = SMi Rj = RMi-1

• IMT: Sj-1 = Xj-1 < Tj < Rj < Sj = Xj

• PMT: Sj-1 < Tj = Xj < Rj < Sj < Tj+1 = Xj+1

•DSR

• Sj-1 = DP,j-1 < Tj = Rj < Sj < Tj+1 : Sj = SMi Rj = RMi-1

• IMT: Sj-1 = DP,j-1 = Xj-1 < Tj = Rj < Sj = Xj

• PMT: Sj-1 < Tj = Xj = Rj < Sj < Tj+1 = Xj+1

Period delayed communication

Single buffer

Periodic Task Communication Summary

Periodic Same period

ASRIMT | PMT

DSRIMT | PMT

P ; CMF:1B PD:2B

SXRPD:2B

PD:2BSX/R

C ; PPD:1B PD:1B PD:1B PD:1B PD:1B

P CND:1B PD:2B

PD:2BR

PD:2BX/R

P | CND:3B

PD:2BX

PD:2BR

PD:2BX/R

NDI:2BS/X/RC

1B: Single buffer

2B: Two buffers

3B: Three buffers

4B: Four buffers

S, X, R : data copy

S/X : IMT combined send/xfer

S/X/R : DMT combined S, X, R

X/R: DSR/PMT combined X, R

o1o2 : One operation copy

MF: Mid-Frame

PD: Period Delay

ND: Non-Deterministic

NDI: No Data Integrity

Outline

The problem

AADL Communication Semantics

• Input frozen at dispatch time• Copy to input buffer at dispatch if required

• Data ports & periodic threads• Immediate connection (DMT)

• Data driven execution or offset start time

• Delayed connection (DSR/PMT)• Transfer by dispatch in runtime system

• Sampling ports • Double buffer for concurrency or down-sampling to ensure data consistency during compute

Peter H Feiler

phf@sei.cmu.edu

Efficient Embedded Runtime Systems through Optimization of Port Communication

Documents

GNNAdvisor: An Adaptive and Efficient Runtime System for ...

Runtime Techniques for Efficient and Reliable Program...

Designing Energy Efficient Communication Runtime Support for...

Outline Highly-efficient embedded organic light emitter .......

Simultaneous Multi-processor Cores for Efficient Embedded...

An Efficient Runtime System for IDL

Efficient Embedded Implementations of Security Solutions for...

© 2006 Carnegie Mellon University Efficient Embedded...

WebAssembly Micro Runtime and use cases for IoT and...

Energy efficient computing on embedded and …...using...

MakeCode and CODAL: Intuitive and Efficient Embedded ...

Binary rewriting and call interception for efficient runtime

PRiMEPower-efficient, Reliable, Many-core Embedded systems

Efficient Runtime Policy Enforcement Using Counterexample

Dennis Stutterheim EMEA BDM, Embedded Servers bij...

Efficient Virtualization on Embedded Power Architecture...