Metrics for Performance Evaluation of Distributed Application Execution in Ubiquitous Computing Environments Prithwish Basu ECE Department, Boston University (Joint work with Wang Ke and Thomas D.C. Little) Project URL: This work was supported in part by NSF under Grant #ANI ACM UbiComp’01 Workshop on Evaluation Methods for Ubiquitous Computing

Overview of our Project We are investigating techniques for modeling distributed UbiComp applications Logical representation of applications in terms of component sub-tasks as resource dependency graphs or task graphs Physical resources are selected on-the-fly just before actual execution of task FocusFocus: Distributed protocols that are adaptive to network partitions due to user/device mobility

A Smart Presentation Application Keyboard Mouse Smart Storage/CPU (possibly mobile) Overhead Display Local Screen Wireless PDA (mobile user) auxiliary devices to control presentation (can be moved) presentation data summary data-flow edge proximity edge The user does not care which particular devices perform the presentation

Task Graphs and Embedding U A B C Task Graph a1 d2 a2 b1 b2 c1 c2 u d1 a1 d2 a2 b1 b2 c1 c2 u d1 Embedding 1 A  a1 B  b2 C  c2 Embedding 2 A  a2 B  b1 C  c1 nodes (colors indicate distinct device categories) non-tree edge tree edges (Paths in G)

Metrics to Evaluate Performance CategorySymbolUnitDescription SpeedT-embedsec. Time taken to discover a mapping Quality Dilationhops Avg. stretch of TG when mapped onto G Node Congestion +ve Real number Avg. number of mapped paths passing through a node in G EfficiencyOverhead #pkts Messaging overhead to find an embedding Resilience to Mobility FrqDisrupt/min. Frequency of application disruption T-recovsec. Time to recover from an app. disruption Application perf. after embedding EffThrptin [0,1] #ADUs recvd. at sink / #ADUs that should have been recvd. under ideal conditions Delaymsec. Time taken by an ADU to reach destn. NumRe-Tx/flow #Re-Tx at source needed for a data flow

Variable System Parameters Topology related: –#Devices in network ~ richness of network connectivity etc. –Fraction of devices that rely on wireless AP / ad hoc routing –Mobility patterns: random  highly predictable Task Graph related: –#nodes in a task/resource graph –Complexity of relationships between nodes of a task graph –#Instances of resources in a network with similar capabilities Traffic related –Average data rates of applications –Background traffic patterns: low load  heavy load –#Instances of simultaneously running tasks