androit real-time for the rest of...

Corporate Technology

AndroitReal-time for the rest of us

Android Builders Summit 2012

Wolfgang Mauerer

Siemens AG, Corporate Competence Centre Embedded LinuxCorporate Research and Technologies, Open Source Platforms

Copyright © 2012, Siemens AG. All rights reserved.

February 14, 2012 Dr. W. Mauerer Corporate Technology T DE TC 4

Corporate Technology

AndroitReal-time for the rest of us

Android Builders Summit 2012

Wolfgang Mauerer, Jan Sawallisch, Gernot Hillier

Siemens AG, Corporate Competence Centre Embedded LinuxCorporate Research and Technologies, Open Source Platforms

S. Honick, S. Oberthur, University Paderborn

Copyright © 2012, Siemens AG. All rights reserved.

Page 1 February 14, 2012 Dr. W. Mauerer Corporate Technology T DE TC 4

Overview

1 Introduction & Rationale

2 PREEMPT RT

3 Androit ArchitectureSoftware ArchitectureDemonstrationPerformance Measurements

4 Building Your Own


Outline


2 PREEMPT RT


4 Building Your Own


Android & Industrial Control I


Android & Industrial Control II


From Android™ to Androit

From Android to Androit

Android and real-time

A bon droit – the right choice!

Business

Machine consolidation

Multi-Coreproliferation






Business

Developer availability

Attractivity sells






Business

Developer availability

Attractivity sells

Technical

Reduced HMI complexity

Opportunity: RT/non-RTseparation

App model

Licensing


Android 6= Embedded Linux

Architecture: (Embedded) LinuxApplications

Framework Applications

POSIX libc

Linux + BSP

C/C++

C

Syscall

IPC

C

Key Concepts

Movecomplexityupwards

Lingua Franca:Java

Consistency

On Philosophy

The whole is greater than the sum of its parts!



Architecture: (Embedded) Android

App

App Framework

CoreLibsDalvik

Bionic

Java

JNI

Binder, JavaApp

Binder

Linux + BSP+ Android Patches

Syscalls

Zygote

Key Concepts

Movecomplexityupwards

Lingua Franca:Java

Consistency

On Philosophy




Architecture: (Embedded) Android

App

App Framework

CoreLibsDalvik

Bionic

Java

JNI

Binder, JavaApp

Binder

Linux + BSP+ Android Patches

Syscalls

Zygote

Key Concepts

Consistency forusers anddevelopers

Convenientand saferlanguages

On Philosophy



Androit: Use Cases

Consumer

In-car entertainment

Home control

Industrial

Small PLCs

Transportation and medicalsystems (Safety?Certification?)


Outline


2 PREEMPT RT


4 Building Your Own


PREEMPT RT: Overview

Goal

Transform Linux into hard RTkernel

Merge Strategy

Merge upstream, by end of year

Roadmap Architecture


PREEMPT RT: Overview

Goal

Transform Linux into hard RTkernel

Merge Strategy

Predictions: Learn from cold fusion

Roadmap Architecture


PREEMPT RT: State of Affairs

Mainline

High-res timers

PI Mutexes

Kernel preemption/Threadedinterrupts

Spinlock annotations

Out of Tree

Lock transformation

Unconditional threadedinterrupts

Latency optimisation, bugfixes

Illustration

Spinlock IRQ Sleeping lock IRQ

Z Z Z

R R R


Outline


2 PREEMPT RT


4 Building Your Own


Androit Architecture: Challenges

Challenges

Android, preempt rt and BSP integration

Propagating real-time “upwards”

Consolidate RT and application model

Asymmetry: HMI vs. RT


Androit: Software Architecture I

Architecture Variants

IntegrateRT-JVM

Extend DVM Hybrid Approach

Application Framework

LibsAndroid Runtime

Applications

Linux Real-Time

Core Libs

Dalvik VM RT-JVM




IntegrateRT-JVM



LibsAndroid Runtime

Applications

Linux Real-Time

Core LibsDalvik VMWith RT

Extensions




IntegrateRT-JVM



Libs Android Runtime

Applications

Linux Real-Time

Core Libs

Dalvik VM

Real-TimeApplications

CommunicationChannel


Androit: Software Architecture II

Architecture


Libs Android Runtime

Applications

Linux Real-Time

Core Libs

Dalvik VM

Real-TimeApplications

CommunicationChannel

Design decisions

Decouple RT and non-RT(Middleware?)

Java coupling: RCU,transactions

Introduce glibc


Demonstration: Measurement Setup

Output Signal

HDMI-Output-Pin:„5V enable“

HDMI-Input-Pin:„hot plug detect“

Input Signal

Interrupt Latency

Signal Generator Oscilloscope

Timer Latency

Android Device„Motorola Xoom“

HDMI cable


Demonstration


Performance Measurements I

Observed Timer Delay [µs]

# s

ampl

es [a

.u.]

1

10

100

1000

1

10

100

1000

CPU 0

100 200 300 400 500

CPU 1

100 200 300 400 500

RT

Non−

RT


Performance Measurements I

Getclock results available

Handler scheduled in

HRT finished

HRT processing

Timer

fires

Timer

expected

3µs 5µs 7µs 30µs 20µs

t

Delay [µs]

# S

ampl

es [a

.u.]

1

10

100

1000

10000

1

10

100

1000

10000

Expiration delay

0 50 100

150

200

250

HRT handler delay

0 50 100

150

200

250

HRT duration

0 50 100

150

200

250

Schedule In

0 50 100

150

200

250

Getclock

0 50 100

150

200

250

RT

Non−

RT


Outline


2 PREEMPT RT


4 Building Your Own


Good, Bad, Ugly

IssuesDevice Access

Sources/BSP

Interfaces

Image Sources: Motorola, gizmodo.de, Freescale, ww1.prweb.com, Wikipedia


Good, Bad, Ugly

BSP Theorem

RBSP(n) ∝ 1

n



Good, Bad, Ugly

Corollary

limn→∞

RBSP(n) = 0



Androit HOWTO

Fo

rwa r

d

BS

P

An

dro

id

Pre

emp

t R

T

Van

ill a

Van

ill a

Van

ill a

Base System Tasks

preempt rt-capable base kernel(BSP!)

Android patches

preempt rt patches

Latency tuning (device drivers!)

Userland Tasks

Android component adaption

RT control integration


Androit HOWTO

# of

Pat

ches

0

50

100

150

200

250

Andro

id Fixe

sBSP

Andro

id

BSP Fixe

s

Gener

ic

Late

ncy

Preem

pt_R

T

Preem

pt_R

T Fixe

s

Base System Tasks


Android patches

preempt rt patches


Userland Tasks




Androit HOWTO#

of P

atch

es

0

10

20

30

40

50

60

Andro

id Fixe

sBSP

Andro

id

BSP Fixe

s

Gener

ic

Late

ncy

Preem

pt_R

T

Preem

pt_R

T Fixe

s

Base System Tasks


Android patches

preempt rt patches


Userland Tasks




Thanks for your interest!


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