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  • dissertation - matière potentielle : and
%NVUEDELOBTENTIONDU %0$5035%&-6/*7&34*5²%&506-064& $ÏLIVRÏPAR $ISCIPLINEOUSPÏCIALITÏ 0RÏSENTÏEETSOUTENUEPAR 4ITRE %COLEDOCTORALE 5NITÏDERECHERCHE $IRECTEURS DE4HÒSE 2APPORTEURS LE MEMBRES DUJURY: Institut National des Sciences Appliquées de Toulouse (INSA Toulouse) Systèmes (EDSYS) Resource allocation in hard real-time avionic systems - Scheduling and routing problems 28 Septembre 2011 Ahmad AL SHEIKH Systèmes Informatiques et Systèmes Embarqués Sanjoy BARUAH (University of North Carolina) Yves SOREL (INRIA) Olivier BRUN (LAAS-CNRS) Pierre-Emmanuel HLADIK (LAAS-CNRS) LAAS-CNRS Frédéric BONIOL (ONERA
  • virtual link
  • architecture components
  • ima-based architectures
  • while significantly ameliorating
  • real-time tasks
  • tasks while
  • scheduling problems
  • scheduling problem
  • hard real-time
  • systems
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InstitutNationaldesSciencesAppliquéesdeToulouse(INSAToulouse)
SystèmesInformatiquesetSystèmesEmbarqués
AhmadALSHEIKH
28Septembre2011
Resourceallocationinhardreal-timeavionicsystems
-
Schedulingandroutingproblems
Systèmes(EDSYS)
LAAS-CNRS
$IRECTEURSDE 4HÒSE
OlivierBRUN(LAAS-CNRS)
Pierre-EmmanuelHLADIK(LAAS-CNRS)
SanjoyBARUAH(UniversityofNorthCarolina)
YvesSOREL(INRIA)
M EMBRESDUJURY :
FrédéricBONIOL(ONERA)
JoëlGOOSSENS(UniversitéLibredeBruxelles)iiAcknowledgements
First and foremost, my appreciation goes to my doctoral advisors, Dr. Olivier Brun and Dr. Pierre-
Emmanuel Hladik for their support throughout my PhD. They have successfully provided me with a
fulfilling and motivating work environment in which I have conducted my research. I thank them for
this unique experience for which Iam deeply grateful.
IwouldalsoliketooffermyappreciationtoDr.BalakrishnaPrabhuforhissupportandcontribution
inmany occasions. Hisintervention had agreat impact onthe direction this thesis has took.
IwouldliketothanktheJuryforhavingacceptedtoparticipate inmyPhDdefense. Beginningwith
Professor Sanjoy Baruah and Professor Yves Sorel who have consecrated much of their time to review
mydissertation andgivedetailedfeedbackonmywork,toProfessorFre´de´ricBoniolandProfessorJoe¨l
Goossens who participated in examining my work and providingvaluableinsightstotheimprovement
ofthe quality ofthis thesis.
Iwouldliketoacknowledgealltheparticipantsintheresearch project SATRIMMAP for the sup-
port theyhave givenmethroughout the3years ofthePhD.Thissupport wasofutmost importance and
wasessential tothe accomplishment ofthe objectives set before us.
IamextremelygratefulforthematesIgottoknowandshareoffices with in the Laboratory of Ar-
chitecture and Analysis ofSystems. Among them, Iwould like to mention Re´miSharrock, Jean-Marie
Codol and Aure´lien Gonzalez, for whom I offer my fondest regards for all of the time we have passed
together. Ihope our friendship continues on.
IwishtothankmyfriendsoutsideworkandwhomIgettocallmy second family: Alaa Allouch,
HoussamArbess,YahyaSalma,NadimNasreddineandseveralothers. Youweretherenexttomewhen
Iwasinneed.Withoutyourcompany,lifewouldn’thavebeenthe sameabroad.
Finally, I would like to dedicate this thesis to my parents, Mustafa and Mervat, who have raised,
taught, supported and guided methroughout mylife.
iiiivAbstract
Thelastcoupleofyearshaveseenaprofoundevolutioninembeddedarchitectures withtheintroduction
ofIntegrated Modular Avionics (IMA).Byoffering toembedded applications astandardized execution
and communication support, these architectures have allowed the consequent reduction of physical
weight and complexity. This low level reduction of complexity is opposed by an increased difficulty
in application conception and integration, as managing resource sharing is through numerous configu-
ration parameters. This thesis is devoted to two resource allocation problems that arise in conception
phases of IMA-based architectures.
The multiprocessor scheduling problem is first addressed forstrictlyperiodictasks,orinother
words tasks that execute indefinitely in equidistant time intervals. The objective is supposed to be
the maximization of the minimal idle time between two tasks while avoiding overlap in temporal ex-
ecutions. This allows guaranteeing a minimal evolution margin for the task executions. An integer
linear programming based formulation is first proposed for this NP-hard problem, integrating all asso-
ciated temporal and resource constraints. Toextend scalability, a heuristic inspired from GameTheory
is equally introduced. In this heuristic, each task adopts a scheduling that maximizes its proper util-
ity function (related to the evolution margin of tasks). The convergence of this algorithm towards an
equilibrium point, where no task has an interest in modifyingitsstrategy,isshowninadditiontothe
presence of a globally optimal equilibrium. The obtained numerical results show that this algorithm is
muchfasterthantheexactmethodandgivesagoodapproximation. Tofurther ameliorate thequalityof
obtained solutions, multi-start methods can be applied to this algorithm to supply probabilistic guaran-
tees on the optimality of attained equilibria.
In the second part of the thesis, the message routing problem between avionic functions in the
AFDXnetworkisconsidered. ThisnetworkallowsthetransmissionofEthernetframesinwhatiscalled
virtuallinks(VL).EachVLcanbeseenasamulticasttreeallowingdatatransmission fromonepointof
thenetworktoseveralothers. Anexactnode-linklinearformulation isfirstintroduced. Thisisfollowed
bythepropositionofatwo-levelheuristicthatcompromisesbetweenthefairloaddistributionanddelay
minimization in the network. The obtained results show that solutions obtained by the heuristic can be
very close to those of the exact method while significantly ameliorating communication delays.
vviCONTENTS
Resu´ me´ et´ endu 1
Introduction 23
1Resourceallocationinavionicsystems 27
1.1 Evolution ofavionic systems . . . . . . . . . . . . . . . . . . . . . . . ..... ... 27
1.2 The Integrated Modular Avionics architecture . . . . . . . . ...... ... 28
1.2.1 Architecture components . . . . . . . . . . . . . . . . . . . . . . . ... ... 30
1.2.2 Theavionics AFDXnetwork . . . . . . . . . . . . . . . . . . . . . . . . ... 30
1.2.3 Partition segregation . . . . . . . . . . . . . . . . . . . . . . . . . ... ... 31
1.3 Overview on thesoftware development process design in avionics . . . . . . . . . . . 35
1.3.1 Requirements analysis phase . . . . . . . . . . . . . . . . . . . . .... ... 35
1.3.2 System design phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 35
1.3.3 Architecture design phase . . . . . . . . . . . . . . . . . . . . . . ... ... 36
1.3.4 Detailed design phase . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 37
1.3.5 Coding phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.3.6 Unit testing phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 37
1.3.7 Integration testing phase . . . . . . . . . . . . . . . . . . . . . . .... ... 37
1.3.8 System testing phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 37
1.3.9 Acceptance testing phase . . . . . . . . . . . . . . . . . . . . . . . ... ... 37
1.4 The research project SATRIMMAP . . . . . . . . . . . . . . . . . . . . .... ... 38
1.5 Objectives of the study . . . . . . . . . . . . . . . . . . . . . . . . . . . .... ... 38
1.5.1 Scheduling objectives . . . . . . . . . . . . . . . . . . . . . . . . . ..... 39
1.5.2 Virtual Link routing objectives . . . . . . . . . . . . . . . . . . ..... ... 40
1.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 41
2Stateoftheart 43
2.1 Introduction toreal-time systems . . . . . . . . . . . . . . . . . .... ..... ... 43
viiviii CONTENTS
2.1.1 Hard real-time systems . . . . . . . . . . . . . . . . . . . . . . . . . ..... 45
2.1.2 Soft real-time systems . . . . . . . . . . . . . . . . . . . . . . . . . ..... 45
2.2 Generalities on real-time scheduling . . . . . . . . . . . . . . ..... ..... ... 45
2.2.1 Real-time tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 46
2.2.2 Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.2.3 Classes ofscheduling problems . . . . . . . . . . . . . . . . . . .... ... 48
2.2.4 Non-preemption inscheduling problems . . . . . . . . . . . .......... 49
2.2.5 Schedulability analysis . . . . . . . . . . . . . . . . . . . . . . . .... ... 49
2.3 Embedded systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 51
2.3.1 Memory management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.3.2 Distributed systems . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... 52
2.3.3 Energy consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 52
2.3.4 Fault-tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 53
2.3.5 Other considerations . . . . . . . . . . . . . . . . . . . . . . . . . . ..... 53
2.4 Complexity of scheduling problems . . . . . . . . . . . . . . . . . .......... 53
2.5 Real-time scheduling algorithms . . . . . . . . . . . . . . . . . . ... ..... ... 54
2.5.1 Uniprocessor scheduling . . . . . . . . . . . . . . . . . . . . . . . ... ... 55
2.5.2 Multiprocessor scheduling . . . . . . . . . . . . . . . . . . . . . .... ... 57
2.5.3 Non-preemptive and strictly periodic multiprocessorscheduling . . . . . . . . 59
2.6 Theoretic concepts for the thesis . . . . . . . . . . . . . . . . . . ... ..... ... 60
2.6.1 Particularities ofthe study . . . . . . . . . . . . . . . . . . . . ..... ... 60
2.6.2 Someknown solution strategies . . . . . . . . . . . . . . . . . . .... ... 61
2.6.3 Gametheory

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