Download - Apresentação no 4o Workshop de Sistemas Distribuídos Autonômicos - WoSiDA 2014 - SBRC 2014
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A Systematic Model-Based Approach for Feedback Control Trade-Off
Evaluation in Autonomic Systems
Sandro S. Andrade e Raimundo J. de A. MacêdoDistributed Systems Laboratory (LaSiD)
Department of Computer ScienceFederal University of Bahia
{sandros, macedo}@ufba.br
XXXII SBRC – IV Workshop de Sistemas Distribuídos Autonômicos – WoSiDA 2014
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Context and Motivation
● Nearly 13 years have elapsed in Autonomic Systems research field
● Different research communities Different →underpinnings for self-management:– Reflexive middleware platforms– Graph grammars– Intelligent agents– Policy-based– Bio-inspired self-organizing structures
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Context and Motivation
● Consequences:– Lack of organized design knowledge for routine use– False intuition and design bias– Sub-optimal architectures for self-management
● A perspective from Software Engineering● Research questions:
– To which extent may autonomic systems design knowledge be systematically represented for routine use ?
– How to support well-informed decision making regarding quality attribute trade-offs between alternative architectures ?
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Our Approach (DuSE)
● We combine the use of ...– Metamodeling and Domain-Specific Languages (DSL)– Structured Architecture Design Spaces– Architecture Quality Metrics– Multi-Objective Optimization
● … in order to …– Enable a more disciplined and automated “handbook”
of autonomic systems design– Provide a solid basis for choosing between
architectures which exhibit different quality attributes
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Our Approach (DuSE) - overview
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Our Approach (DuSE) - examples
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Our Approach (DuSE) – design space
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SA:DuSE – design dimensionsVP11: ProportionalVP12: Proportional-IntegralVP13: Proportional-Integral-DerivativeVP14: Static State FeedbackVP15: Precompensated Static State FeedbackVP16: Dynamic State Feedback
DD1: Control Law
VP31: Fixed Gain (no adaptation)VP32: Gain SchedulingVP33: Model Identification Adaptation Control
DD3: Control Adaptation
VP21: Chien-Hrones-Reswick, 0 OS, Dist. RejectionVP22: Chien-Hrones-Reswick, 0 OS, Ref. TrackingVP23: Chien-Hrones-Reswick, 20 OS, Dist. RejectionVP24: Chien-Hrones-Reswick, 20 OS, Ref. TrackingVP25: Ziegler-NicholsVP26: Cohen-CoonVP27: Linear Quadratic Regulator
DD2: Tuning Approach
VP41: Global ControlVP42: Local Control + Shared ReferenceVP43: Local Control + Shared Error
DD4: MAPE Deployment
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SA:DuSE – quality metrics
M2: Average
Settling Time
ME2=allOwnedElements ()→ selectAsType(QParametricController )→sum(stime())
allOwnedElements()→selectAsType(QParametricController )→size ()
; where QParametricController : : stime()=−4
log(maxi∣p i∣);and max i∣pi∣is themagnitude of thelargest closed−loop pole
M1: Control
OverheadME1=
allOwnedElements ()→ selectAsType (QController )→ collect(overhead ())→sum ()
allOwnedElements ( )→selectAsType (QController )→size()
;QController : : overhead( )increasingly penalizes VP32, VP33, VP41and VP43
M4: Control
RobustnessME4=
allOwnedElements ()→ selectAsType(QController )→collect (robustness())→sum ()
allOwnedElements()→selectAsType(QController )→size()
;QController : :robustness()increasingly penalizesVP31 andVP32
M3: Average
Maximum Overshoot
ME3=allOwnedElements()→selectAsType(QParametricController)→sum (maxOS ())
allOwnedElements()→selectAsType(QParametricController )→size ()
; where QParametricController : : maxOS ()={0 ;real dominant pole p1≥0
∣p1∣;real dominant pole p1<0
r π/∣θ∣;dominant poles p1, p2=r.e±j. θ}
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Our Approach (DuSE) - optimization
● Even small input models generate huge design spaces:– 3 controllable components 54,010,152 candidates→– 4 controllable components 20,415,837,000 →
candidates● Multi-objective Optimization:
– NSGA-II evolutionary backend– The output is a set of Pareto-optimal architectures:
● They differ only on which quality metric is favored
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Our Approach (DuSE) - optimization
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Evaluation – tool support
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Evaluation
● Evaluation dimensions:– Is autonomic systems design indeed a multi-objective
problem ?– To which extent the quality of Pareto-optimal
architectures are indeed observed in real prototypes ?– Do search-based approaches improve the design of
autonomic systems ?
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Evaluation
● Evaluation dimensions:– Is autonomic systems design indeed a multi-objective
problem ?– To which extent the quality of Pareto-optimal
architectures are indeed observed in real prototypes ?– Do search-based approaches improve the design of
autonomic systems ?
Multi-objective quality indicators:
hypervolume and generational distance
#=9.7GD=0.12
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Evaluation
● Evaluation dimensions:– Is autonomic systems design indeed a multi-objective
problem ?– To which extent the quality of Pareto-optimal
architectures are indeed observed in real prototypes ?– Do search-based approaches improve the design of
autonomic systems ?
Multi-objective quality indicators:
hypervolume and generational distance
#=9.7GD=0.12
Real prototypes of feedback controllers in distributed MapReduce
architectures21 machines Hadoop 2.3
clusterSettling Time error = 2%
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Evaluation
● Evaluation dimensions:– Is autonomic systems design indeed a multi-objective
problem ?– To which extent the quality of Pareto-optimal
architectures are indeed observed in real prototypes ?– Do search-based approaches improve the design of
autonomic systems ?
Multi-objective quality indicators:
hypervolume and generational distance
#=9.7GD=0.12
Real prototypes of feedback controllers in distributed MapReduce
architectures21 machines Hadoop 2.3
clusterSettling Time error = 2%
A controlled experiment(24 students)
H01: GD(ra)=GD(ia) ☑H02: AC(ra)=AC(ia) ☑H03: QG(ra)=QG(ia)
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Conclusion
● Limitations:● Only feedback control concerns up to now● We assume an initial annotated architecture model is
available● No guaranteed optimality (local Pareto-fronts)
● Contributions:● A domain-independent infrastructure for design space
specification● First search-based approach to self-managed systems
architectural design● 2nd controlled experiment involving self-managed systems● A design space exploration tool
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Obrigado !
Sandro S. Andrade e Raimundo J. de A. MacêdoDistributed Systems Laboratory (LaSiD)
Department of Computer ScienceFederal University of Bahia
{sandros, macedo}@ufba.br