Modeling with Parallel DEVS

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Modeling with Parallel DEVS
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Serialization in DEVS models

• Select function
• Implicit serialization of parallel models
• E-DEVS internal transition first, external
  transition after
• Inadequate representation of DEVS models
  with parallel components

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Parallel DEVS Atomic Models
DEVS lt Xb, S, Yb, dint , dext , dconf , ta, l gt
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Parallel DEVS Atomic models
DEVS lt Xb, S, Yb, dint , dext , dconf , ta, l gt
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Parallel DEVS Atomic models
DEVS lt Xb, S, Yb, dint , dext , dconf , ta, l gt
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Parallel DEVS Atomic models
DEVS lt Xb, S, Yb, dint , dext , dconf , ta, l gt
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Parallel-DEVS Coupled models

• Components
• Couplings
• Internal
• External Inputs
• External Outputs

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Simulation mechanism

• Simulation advanced through message exchange
• Synchronization messages
• Type Action
• ( _at_, t ) Output execution
• ( , t ) State transition
• ( done , t ) End of action
• Content messages
• ( y , t ) Output event
• ( q , t ) External event

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Simulator

• Drives atomic models
• State
• tN time of next transition
• tL time of last transition
• message bag
• Upon receiving Do
• ( _at_, t ) y l (s) send ( y, t )
• (q, t) Add q to message bag
• ( , t )
• if t lt tN s dext tN ta(s) tL t
• if t tN ? bag ? s dint tN ta(s)
  tL t
• if t tN ? bag ? ? s dconf tN ta(s)
  tL t

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Coordinator

• Coordinates processors activities

Coordinator
tN 10
tN 10
tN 20
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Coordinator
Coordinator
tN 10
tN 10
tN 20
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Coordinator
Coordinator
tN 20
tN 30
tN 15
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Parallel CD

• A tool to execute Parallel DEVS and Parallel
  Cell-DEVS models in parallel/distributed
  environments
• Layered architecture based on Warped

Parallel CD
Warped
MPI (Message Passing Interface)
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Parallel - DEVS simulation

• Independent of the modelling technique
• Different simulators can be applied according to
  the needs.
• Examples of existing simulators
• Hierarchical
• Flat
• Centralized
• Distributed
• Real-Time

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Parallel DEVS simulation

• Processors
• Simulator Atomic model
• Coordinator Coupled model
• Processor hierarchy model hierarchy

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CD Parallel simulator

• Model partitioned among available CPUs
• Atomic models
• Each atomic model assigned to a CPU
• Coupled models
• Coordinator is placed on each CPU where there is
  a component

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Parallel simulation mechanism
CPU 1
CPU 2
Slave coord.
Master coord.
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Parallel simulation mechanism
CPU 1
CPU 2
Slave coord.
Master coord.
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Extensions to CD
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Extensions (cont.)
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Partition Files
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• RADS (Carleton University)
• Alpha network and Gamma network

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Simulation Results

• Generator- Processor-Transducer
• Multiple instances (12, 48 and 96)
• 1 to 12 CPUs (different machines)

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Results
Generator - Processor - Transducer
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Results

• Heat diffusion model
• 100 x 100 surface
• Each cell holds a temperature value
• Temperature is update periodically
• Partitions
• 1, 2, 4 and 8 CPUs
• Quantization
• Quantum sizes
• 0 0,001 0,01 y 0,1

10000
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Results

• Heat diffusion - Linux cluster

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Results

• Heat diffusion - 4 processors SMP