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Transcript of Cache Invalidation and Replacement Strategies for Location-Dependent Data in Mobile Environments...
Cache Invalidation and Replacement Strategies for Location-Dependent Data in Mobile Environments
Speaker : Hsin-Chin Mao
Fu Jen Catholic UniversityComputer Science and Information Engineering Department
High Speed Networks Lab2003/10/28
Outline
Introduction The System Model Location-Dependent Invalidation Strategies Location-Dependent Cache Replacement
Policies Simulation Model Performance Evaluation Conclusion References
Introduction
two common issues in client cache management cache invalidation scheme cache replacement policy
location-dependent data location-dependent cache invalidation valid scopes
We first introduce two basic location-dependent invalidation schemes Polygonal Endpoints (PE) Approximate Circle (AC)
a generic method Cache-Efficiency Based scheme (CEB)
The System Model
two distinct sets of entities mobile clients fixed hosts ( mobile support stations (MSSs))
data item value from data item Mobile clients can identify their locations usin
g systems such as the Global Positioning System (GPS)
cache data values on its local disk or in any storage system; fixed sizes and read-only
Location-Dependent Invalidation Strategies The advantages of the idea that attach
complete/partial invalidation information two situations where validity checking is
necessary cache replacement policies
The Polygonal Endpoints (PE) Scheme a straightforward way
The Approximate Circle (AC) Scheme the overhead of this scheme can be minimized 56 bytes => 12 bytes
Location-Dependent Invalidation Strategies The Caching-Efficiency-Based (CEB) Method
Location-Dependent Cache Replacement Policies Data Distance
the distance between the current location of a mobile client and the valid scope of a data value
Valid Scope Area the geometric area of the valid scope of a data value propo
sed PA and PAID policies Probability Area (PA)
Probability Area Inverse Distance (PAID)
Simulation Model
System Execution Model 110 points randomly distributed in a square Euclid
ean space the locations of 185 hospitals in the Southern Calif
ornia area Server Execution Model Client Execution Model
Performance Evaluation
Evaluation of Location-Dependent Invalidation Schemes
Evaluation of Cache Replacement Policies uniform access (θ=0), skewed access(θ=0.5) Effect of Changing Query Interval Effect of Changing Moving Interval Effect of Cache Size
Effect of Combining Different Invalidation and Replacement Schemes
Evaluation of Location-Dependent Invalidation Schemes
Evaluation of Location-Dependent Invalidation Schemes
Evaluation of Location-Dependent Invalidation Schemes
Effect of Changing Query Interval
Effect of Changing Query Interval
Effect of Changing Moving Interval
Effect of Changing Moving Interval
Effect of Cache Size
Effect of Combining Different Invalidation andReplacement Schemes
Conclusions
explored cache invalidation and replacement issues for location-dependent data under a geometric location model PE, AC, CEB
proposed two cache replacement policies PA, PAID
future work location-dependent queries
References
Baihua Zheng, Jianliang Xu, Dik Lun Lee: Cache Invalidation and Replacement Strategies for Location-Dependent Data in Mobile Environments. IEEE Transactions on Computers 51(10): 1141-1153 (2002)
Q. Ren and M.H. Dunham, “Using Semantic Caching to Manage Location Dependent Data in Mobile Computing,” Proc. Sixth Ann. ACM/IEEE Int’l Conf. Mobile Computing and Networking (MobiCom 2000), pp. 210-221, Aug. 2000.
G.K. Zipf, Human Behaviour and the Principle of Least Effort.Addison-Wesley, 1949.