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Efficient Proactive Caching for Supporting Seamless Mobility
Vasilios Siris, Xenofon Vasilakos, George PolyzosPhD student, AUEB, MMLAB
mm.aueb.gr/[email protected]
Approach (1/2)
• Proactively fetch data‐objects to attachment points
• Is this a typical proactive caching approach?
Xenofon Vasilakos ‐ [email protected] 3
Approach (2/2)
• Handoff mobility probabilities
• Exploit Individual mobility & requests– Not data‐popularities
Xenofon Vasilakos ‐ [email protected] 4
Efficient Proactive Caching (EPC)
• Individual requests imply higher demand forcache space
• Congestion pricing for cache storage– Efficient cache utilization
EPC trades cache space (price) for reduced delay (delay cost)
Xenofon Vasilakos ‐ [email protected] 5
Outline
1. EPC in a flat cache structure2. EPC in a two‐level cache hierarchy3. Evaluation
Xenofon Vasilakos ‐ [email protected] 6
Flat cache structure
• Decision Rule:
Autonomous prefetching/ cachingXenofon Vasilakos ‐ [email protected] 7
Flat cache structure
• Step‐wise decision procedure– Optimal selection of cached objects?
Xenofon Vasilakos ‐ [email protected] 8
Flat cache structure
• Optimal selection of cached objects?1. Objects with different sizes
• Optimization is identical to 0/1 Knapsack Problem• NP‐hard problem
2. Optimal for equal‐size objects• For each cache and each request , order by
Xenofon Vasilakos ‐ [email protected] 9
Hierarchical cache structure
Xenofon Vasilakos ‐ [email protected] 10
Hierarchical cache structure
• Leafs solve 2 flat cache problems :1. Delay DR
2. Delay DM
•
Xenofon Vasilakos ‐ [email protected] 11
Requires cooperation
Finding an optimal solution ?
• Data Placement Problem – Different object sizes => NP‐complete– Equal size objects => high polynomial degree time
Xenofon Vasilakos ‐ [email protected] 12
EvaluationComparison with a naive, an optimal, and an oracle scheme
Xenofon Vasilakos ‐ [email protected] 13
EvaluationComparison with a naive, an optimal, and an oracle scheme
Xenofon Vasilakos ‐ [email protected] 14
EvaluationComparison with a naive, an optimal, and an oracle scheme
Xenofon Vasilakos ‐ [email protected] 15
Evaluation
Xenofon Vasilakos ‐ [email protected] 16
Evaluation
Xenofon Vasilakos ‐ [email protected] 17
Comparison with a naive, an optimal, and an oracle scheme
A distributedmobility support solutiontailored to individual user mobility/requests that
exploits user mobility and uses congestion pricing
Xenofon Vasilakos ‐ [email protected] 18