Motivation
Migration-aware and CRMD
Experimental results
Conclusions and ongoing work
Estimation of Cache Related Migration Delays for
Multi-core Processors with Shared Instruction
Caches
Damien Hardy
Isabelle Puaut
University of Rennes - IRISA
17th International Conference on Real-Time and Network
Systems, October 2009
Damien Hardy, Isabelle Puaut
CRMD for Multi-Core Processors
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Motivation
Migration-aware and CRMD
Experimental results
Conclusions and ongoing work
Real-time systems
Real-time: Timing constraints
All tasks have to meet their deadlines
Temporal validation
⇒ Estimation of Worst-Case Execution Time (WCET)
⇒ Estimation of preemption delays
⇒ Estimation of migration delays
Damien Hardy, Isabelle Puaut
CRMD for Multi-Core Processors
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Motivation
Migration-aware and CRMD
Experimental results
Conclusions and ongoing work
Real-time systems
Estimation of WCET
Safety: to ensure respect of timing constraints
Upper bound
Tightness: to avoid overestimation of the resources required
Solutions for caches:
Considering a miss for each access
⇒ leads to a huge overestimation
Measurement ⇒ unsafe
Hard to execute tasks in their
worst-case scenario (especially for
multi-core platforms)
⇒ Static analysis
Damien Hardy, Isabelle Puaut
CRMD for Multi-Core Processors
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Motivation
Migration-aware and CRMD
Experimental results
Conclusions and ongoing work
Real-time systems: multi-core processors
Multi-core processors have been introduced
Performance improvements, power consumption. . .
Observation Task’s migration is allowed during its execution
Scheduling possibilities: Global scheduling
Migration cost
Assumed to be zero or constant
How to compute the migration cost?
Damien Hardy, Isabelle Puaut
CRMD for Multi-Core Processors
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Motivation
Migration-aware and CRMD
Experimental results
Conclusions and ongoing work
Task migration
Task running on core 1
Cache blocks loaded from
main memory
Task migration from core 1
to core 2
Direct impact
Registers: save and
restore. . . (δ)
Indirect impact
Private cache con