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Self-Tuned Remote Execution for Pervasive Computing
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Transcript of Self-Tuned Remote Execution for Pervasive Computing
Self-Tuned Remote Execution for Pervasive ComputingJason Flinn, Dushyanth Narayanan and M.Satyanarayanan
Presented by:Kevin McGregor
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Outline
Motivation Spectra
o Design goalso Overviewo Implementationo Preliminary Evaluationo Strength and Weaknesso Future work
Summary
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Motivation Need for mobility. Size limitation on
mobile devices. Modern applications
are resource intensive.
Mobile users want the look and feel of desktop applications.
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Solution Remote execution.
o Mobile device discover execution servers over a wireless network.
o Mobile device “off-load” the execution of resource-intensive processes onto the remote server.
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Spectra : Design Goals Spectra tries to meet the
application goals in the light of available resources.
Monitors mobile devices resources and dynamically determines the best remote execution plan bandwidth, file cache state, CPU, and
battery life.
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Spectra : Design Goals
Applications do not specify resource needs.
Spectra uses a method called self-tuning. Records and logs the history of resource
usage by an application. Uses machine learning techniques to predict
future usage.
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Spectra - Overview Remote execution
component of Aura. Coda Provides a single
shared file system. Applications use
Odyssey interface to communicate with Spectra.
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Spectra : Implementation
Spectra consists of three main components Application interface Resource Monitor Decision Engine
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Spectra : Implementation
Application Interface Applications register operations
Fidelities. Input parameters that affect operation
complexity. Method of dividing computation.
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Spectra : Implementation
Application Interface Method of dividing computation
Local mode – client Remote mode – server Hybrid mode – Application executed
locally then executed remotely
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Spectra : Implementation
Resource Monitors Prior to execution, resource monitor
predict how much of resource is needed. Makes prediction for the mobile device
and remote servers. Gathers prediction in a resource
snapshot. Observe application behavior to predict
future resource demand.
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Spectra: Implementation
Resource Monitors CPU
CPU cycle consumption Network
Available bandwidth. Battery
Amount of charge. File cache
Files in Coda file system.
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Spectra: Implementation
Resource Monitor Battery
Takes advantage of ‘smart’ batteries chips.
Monitors the amount of charge left. Measures energy use by polling the chip
to sample energy use.
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Spectra : Implementation
Resource Monitor File cache
Calculate the time and energy cost of fetching uncached items
Provides estimate for files accessed in Coda.
For each file that may be accessed, Coda is queried to determine if file is cached.
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Spectra : Implementation
Decision engine Chooses a location and fidelity for each
operation. Inputs : Application’s operation
description, monitors’ snapshot of resource availability.
Odyssey’s attempts to find the best execution alternative.
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Spectra : Implementation
Decision Engine Evaluates alternatives by their impact on user
metrics Execution latency Battery life time Application latency
Calculates a context-independent value for each metric.
Weights each value with an importance function.
Computes a single value for evaluating the alternative.
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Spectra : Implementation
Decision Engine battery lifetime example
User metric : duration battery should last
Battery importance function (1/E) c
c : critical energy use at present moment E : expected energy use Spectra adjusts c using estimates of
battery charge and power used reported by battery monitor
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Preliminary Evaluation
Speech recognition application. Mobile device :Compaq Itsy v2.2
pocket with a 206 MHz SA-1100 processor, 32MB DRAM
Server : IBM T20 laptop, 700 MHz PIII,256MB DRAM
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Preliminary Evaluation
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Strength and weakness
Focuses on pervasive computing Attempts to preserve resources
when executing an application. Application developers must
modify their applications Does not choose the optimal
execution plan
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Future work
Spectra developers are aware of the weaknesses.
Currently creating a new remote execution system called Chroma Adaptive Automatic code generation for
developers.
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Summary
Introduced Spectra. Describe how spectra is tries to
preserve resources. Observed an preliminary
evaluation of Spectra. Chroma.
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Questions ?