sflr-tutorial-guide

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TutorialGuide: TheSunflowerToolSuite
HardwarePrototypesandSoftwareResearchPlatformsfor
Failure-ProneandResource-ConstrainedEmbeddedSystems
1 2PhillipStanley-Marbell ,DianaMarculescu
1 TechnischeUniversiteitEindhoven,
DenDolech2,Eindhoven5612AZ,TheNetherlands.
%[phone]
2 DepartmentofECE,CarnegieMellon,
5000ForbesAve.,Pittsburgh,PA15213-3890, USA.
Abstract. In computing systems research, software tools (notably, simu-
lators) provide low-cost, flexible, and low turn-around time facilities for
investigations, but abstract away many hardware details. Hardware im-
plementations onthe otherhand, providetheultimateproofsofconcept,
butrequirehardwaredesignexpertise,areusuallyexpensiveand inflexi-
ble,andarenotalwaysdesignedtoexposeallpossiblesystemparameters
to researchers. They are also rarely the subject of active evolution over
timeasresearchplatformsintheirownright,assoftwaretoolsare.
TheSunflowertoolsuiteisasuiteofhardwareplatformsandsimula-
tion tools, intended to address these concerns. It comprises a full-system
(embedded microarchitecture, networking, power, battery, device failure
and analog signal modeling) simulator, a miniature energy-scavenging
hardware platform, and a handheld computing device. The suite is in-
tended to provide a set of complementary platforms for research in
micro- and system-architectures for embedded systems, with emphases
onenergy-efficiencyandfault-tolerance.Thistutorialwillprovidetheau-
diencewithaworkingknowledgeofthedesign,implementationand us-
ageofthecomponentsoftheSunflowertoolsuite.
1 TutorialObjectives
The objectives of the tutorial are to provide a working knowledge of the use
of the Sunflower full-system simulator, and Sunflower hardwareplatforms, to
computingsystemsresearchers.Thetutorialcoverstwomaintopicareas:
Ê Using and extending the Sunflower full-system simulator; the tutorial
will detail the implementation of, and the facilities provided by, the Sun-
flower framework for performing full-system simulation (microarchitec-
ture, networking, power dissipation and supply, failure-modeling, and
more,)ofnetworksofembeddedsystems.
Ë Using the Sunflower hardware platforms; the simulation framework is
complemented by open hardware platforms, and the tutorial will outline
the process of using the hardware platforms in experimental evaluations
andresearchdeployments.2 P.Stanley-Marbell,D.Marculescu
1.1 Intendedaudience
Thetutorialistargetedatseveralpotentialaudiences:
u Microarchitecture researchers, who are looking for a microarchitectural
simulator for embedded systems that provides detailed models of the
whole system that surrounds a processor or microcontroller. The tutorial
willbeofparticularinteresttoresearchersinvestigatingsystemscontaining
multiple(wiredorwirelessly)networkedprocessingelements,thoseinves-
tigating the interaction of computation with input signals such as sensors,
andresearchersinvestigatingtheeffectsofsoft-errors.
u Sensor network researchers interested in investigating the computational
aspectsoftheirprotocolsandsystemssoftware.
u Systems researchers looking for a platform to enable them to develop
compilers and operating systems for embedded systems, that has greater
flexibility, transparencyand lower cost than hardware,but is also comple-
mented/calibratedagainstactualavailablehardware.
1.2 Whatyoushouldexpecttogetoutofthistutorial
Attheendofthisthreehourtutorial,itishopedthatyouwouldhavegained:
u Theability to usethe Sunflowersimulation environment to modela single
processoror networkedsystem ofembeddedprocessors,given anexisting
systemconfiguration,andtointerpretthebehaviorofthemodeledsystem.
u Theabilitytodefinenewsystemconfigurationsforsimulation,andtocom-
pileC-languagebenchmarksforsimulationinSunflower.
u A knowledge of the available resources for information on the simulation
platform’sbuilt-infacilities,aswellasinformationoncustomizingthesim-
ulatorviaruntimeorcompile-timeconfiguration,orsource-codemodifica-
tion.
u AnunderstandingofthebasicarchitectureoftheSunflowerhardwareplat-
forms,andtheircapabilities.
u The ability to request new features in the periodic revisions of the Sun-
flowerhardwareplatforms.
2 Background
There exist an abundance of tools for many aspects of computing systems
research, from microarchitectural simulators that are the mainstay of com-
puter architecture research [Augustetal.; Burgeretal., 1996], to networking
simulators and other domain-specific tools. Academic research tools are sel-
dom calibrated against specific hardwareplatforms during their development
and evolution, and retrospective comparisons often yield interesting observa-
Gibsonetal., 2000; Langendoen, 2006]. Even when the simulation plat-tions [
forms areindeedcalibratedagainsthardware,thereis seldomthe opportunityLED
TutorialGuide: TheSunflowerToolSuite 3
to evolvethe hardwareplatformsinquestion. This is dueboth tothe expertise
requiredfor implementing hardwaredesigns, as well asthe cost of fabrication
of hardware prototypes. For high-performance computing systems research,
the RAMP platform [Arvindetal., 2005] addresses many of these concerns,
providinganopenplatformforresearchintomultiprocessorarchitectures.The
goal of the Sunflower tool suite is to provide an actively evolving ecosystem
of both hardware prototypes and simulation / analysis tools, for low-power
embeddedsystems, withanemphasisontheinvestigation ofissuesrelatingto
energy-efficiency, energy acquisition, fault-tolerance, and impact of hardware
deploymentsontheenvironment.
Failure Modeling
Failure Modeling0
NetworkSignal Propagation Model
Medium 1
Analog Sensors
Data Transmission Model 1 Analog Microarchitecture
signal 1 Simulation
Network
Interfaces2
Time-varying amplitude Network
Power Estimation Power EstimationMedium 2Spatial attenuation model
Voltage Regulator Model
Analog NetworkAnalog
4 3 signal 2Medium 3signal 3 Battery Model
Fig.1. IllustrativeexampleoftheSunflowerfull-systemsimulator’sorganization.
On the side of simulation, the Sunflower full-system simula-
tor [Stanley-MarbellandMarculescu, 2007b] (Figure 1) enables the evaluation
of micro- and system-architectures for networked embedded systems, model-
ingmanyaspectsofboththehardwareplatformsandtheenvironmentswithin
whichtheyexecute.
Top surface and size
illustration:
MicrophoneFlash Memory
2.7V
SPI ADC
GPIO, UART
Microcontroller
1.8V
Bottom surface:SRAM Flash Memory
GPIO
GPIO ADC
Color Sensor Accelerometer
2.7V
Fig.2. System architecture of the Sunflower sensor platform (left), and pictures of the
currenthardwareprototype(right).
UART0 UART2
Core
CPLD
I/O
Temperature
Sensor
Voltage Regulator
Energy-Scavenging
Subsystem4 P.Stanley-Marbell,D.Marculescu
The Sunflower sensor platform[Stanley-MarbellandMarculescu,2007a](Fig-
ure2),isonephysicalrealizationofcomponentsmodeledwithintheSunflower
full-systemsimulator,enablingthecalibrationandvalidationofsimulatorcon-
figurationsagainstrealhardwareimplementations.
Fig.3. The Sunflower mobile client platform has a 320×240 pixel color display (1), hu-
midity/temperature(3),andpressuresensors(4),andadigitalcompass(6).Itincludesa
dedicatedexpansionconnector(5),USB(7),andan802.15.4radiointerface(2),aswellas
amicroSDslotforflash memoryor peripheralcards.Theprimarysourceofcomputing
power is a 32-bit ARM7 implementation (AT91SAM7S256) with 64KB of on-chip RAM
and 256KB of on-chip flash memory (on the rear side of the device), and the system is
poweredbyathin2000mAhrechargeablelithiumpolymerbattery.
3, with its system architectureThe Sunflower mobile client platform (Figure
shown inFigure4)isanothermemberofthesuiteofhardwaretools,andisin-
tendedto beused,forexample,to studythehardwareandsoftwareaspectsof
buildinglow-powermobilecomputing platformscontaining multipleprocess-
ingelements.
Additionalhardwareplatformswith complementaryhardwarecapabilities
(e.g., wireless communication interfaces and graphical displays) are planned,
anditisintendedtoemploytheseplatformsasaframeworkfortheimplemen-
tation of ideas by a community of researchers who may not necessarily have
interests or expertise in hardwaredesign, but might require specific hardware
facilitiestoenabletheinvestigationofnovelsoftwarealgorithms.
1
2
3
4
5
6
7TutorialGuide: TheSunflowerToolSuite 5
320x240 pixel 18-bit color OLED display
Input Device
System Processor
(Atmel AT91SAM7S ARM7)
Sensors
Atmospheric
System Controller pressure
(TI MSP430F2274)
Display Controller Voltage Regulation, Gating, Humidity ...
(TI MSP430F2370)& and Current Monitoring
Temperature
Rechargeable
Battery
802.15.4
Digital Low-
Radio
Compass Power
Real-Time
RSSIUSB microSD
Clock
Interface between system controller and peripherals / sensors
Power supply
Fig.4. System architecture; The system controller implements the low-level software in-
terfaces to peripherals and sensors, and applications run over the system processor, an
ARMprocessorrunningFreeRTOS.
3 TutorialOutline
Theplannedoutlineoftopicstobediscussedinthetutorialisasshownbelow:
Topic Duration
Motivationforthesuiteofhardwareandsimulationtools 5m