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Reducing the Energy Usage of Office Applications PowerPoint PPT Presentation


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Reducing the Energy Usage of Office Applications. Eyal de Lara Dan S. Wallach Willy Zwaenepoel Rice University. Jason Flinn M. Satyanarayanan Carnegie Mellon University. Motivation. Energy is a vital resource in mobile computing Previous work shows value of energy-aware adaptation

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Reducing the Energy Usage of Office Applications

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Reducing the energy usage of office applications l.jpg

Reducing the Energy Usage of Office Applications

Eyal de Lara

Dan S. Wallach

Willy Zwaenepoel

Rice University

Jason Flinn

M. Satyanarayanan

Carnegie Mellon University


Motivation l.jpg

Motivation

  • Energy is a vital resource in mobile computing

  • Previous work shows value of energy-aware adaptation

    • Reduce fidelity

    • Requires modification to application source code

      Can this work without source code?

      Middleware-based proxy can help!


Validation l.jpg

Validation

  • Common office applications can be made energy-aware

    • Puppeteer uses well-defined data format and API

    • Modified PowerPoint to reduce energy usage

  • Preview of results:

    • Energy reductions up to 49% for some activities

    • Proxy approach modifies PowerPoint behavior

    • Other opportunities for increased energy-efficiency


Outline l.jpg

Outline

  • Motivation

  • Background: Puppeteer

  • Energy benefits of adaptation

  • Other opportunities for extending battery lifetime

  • Future work and conclusions


Component based adaptation l.jpg

skeleton

reintegrated

on save

missing

component

high-fidelity

component

reintegrated

on save

Component-Based Adaptation

Documents often stored on a central file server

Must download and edit on a mobile client

Can save time and energy by editing a low-fidelity version

Server

Client


Puppeteer l.jpg

Server

Proxy

Client

Proxy

Transcoded

Documents

Documents

Server proxy parses and transcodes documents

Client proxy uses external API to interact with PowerPoint

How much energy can component-based adaptation save?

Puppeteer

Uses well-defined data formats, exported APIs

Server

Client

Data

Server

PowerPoint


Measuring application energy usage l.jpg

Event

Start

Event

End

Measuring Application Energy Usage

Digital multimeter samples laptop power use

Applications mark start and end of events

Energy usage is integral of power over time


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Benchmark Presentations

Benchmark consists of 10 PowerPoint presentations

Size and effect of distillation vary


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Experiment: Loading Documents

  • Client: IBM 560X laptop with 2 Mb/s wireless network

  • Server: Wall-powered desktop

  • Client runs NT, PowerPoint, Puppeteer client proxy

  • Server runs NT, Apache, Puppeteer server proxy

  • Measure energy used to load documents:

    • From Apache (native mode)

    • Using Puppeteer (distilling out multimedia data)


Energy benefit for loading documents l.jpg

Oops!

Energy Benefit for Loading Documents

Average energy usage reduced 40%!

With simple filter, energy usage reduced 49%!


Experiment editing documents l.jpg

Experiment: Editing Documents

  • Load documents on the client

  • Measure energy needed to page through document for:

    • Full-quality version

    • Distilled version


Energy benefit for editing documents l.jpg

Energy Benefit for Editing Documents

Distillation reduces paging energy 13%

Benefit less on subsequent traversals of document


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Reducing Computational Fidelity

How much energy is used by background activities?

Not a lot to be gained by disabling most activities . . .

But, the Office Assistant is quite expensive!


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Experiment: Autosave Frequency

  • Documents are saved on the client

    • Autosaves over network prohibitively expensive!

    • Reducing frequency saves energy

    • But, greater possibility of losing data!

  • Measure additonal power savings for autosave frequency:

    • One minute (very expensive)

    • Five minutes (less expensive)

    • No autosave (optimal savings)


Effect of autosave frequency l.jpg

Effect of Autosave Frequency

Average energy reduction of 11%


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Outline

  • Motivation

  • Puppeteer: component-based adaptation

  • Energy benefits of adaptation

  • Other opportunities for extending battery lifetime

  • Future work and conclusions


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Comparing Puppeteer and Native Mode

Mystery: Why does Puppeteer take less time and energy to load a presentation than native mode?


Effect of network power management l.jpg

Effect of Network Power Management

  • Hypothesis: power management slows down transfer

    • Network receiver disabled for 100 ms. periods

    • Wireless bandwidth 2 Mb/s

    • In effect, a high bandwidth*delay product (25 KB)

    • Socket buffer and receive window only 8 KB

    • Native mode uses only 1 connection

    • Puppeteer uses up to 4 connections

      Verified this hypothesis by measuring:

    • With 64KB buffer sizes

    • Without network power management


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Network Power Management Results

With 64 KB buffers, native mode uses 26% less energy

Disabling power management saves additional 18%


Disk power management l.jpg

Autosave

Disk spinning = Wasted Energy

Disk Power Management

Disk power management predicts periods of inactivity

After autosave, waits for additional activity

Disk in high-power state for 30 seconds


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Transparent Power Management

  • Applications and power mgmt. layer don’t communicate

    • Power management balances performance & energy

    • Tries to minimize impact on applications

    • Difficult without knowledge of application activity

      Transparent power management can help!

    • Applications provide hints about their activities

    • OS combines hints from all applications

    • OS chooses the optimal power mgmt. settings

CPU

Power Mgmt.

Settings

Transparent

Power

Management

Layer

Network

Hints

Applications

Disk


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PowerPoint and Power Management

  • Puppeteer could provide PM hints for PowerPoint

  • Signals start and end of large transfers

    • Power management disabled during transfers

    • Uses 18% less energy, 22% less time

  • Signals when regular autosave is occurring

    • Can spin-down disk immediately after autosave

    • Uses 4% less energy


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Outline

  • Motivation

  • Puppeteer: component-based adaptation

  • Energy benefits of adaptation

  • Other opportunities for extending battery lifetime

  • Future work and conclusions


Future work l.jpg

Future Work

  • System support for energy-aware applications

    • Currently open-source implementation (Linux)

    • Monitors supply and demand, adjusts fidelity

    • Port to closed-source environment (Windows)

      Transparent power management

    • Create API for expressing application hints

    • Develop algorithms that combine hints

    • Investigate other hardware devices (CPU)


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Conclusions

  • No one magic bullet for reducing PowerPoint energy use

  • But, many opportunities for significant energy reduction

    • Reducing data fidelity

    • Reducing computational fidelity

    • Transparent power management

      Puppeteer provides a mechanism for achieving reductions

    • Proxy approach requires no source-code modification

    • Takes advantage of exported APIs

      Other potential domains for this work:

    • Other Microsoft Office applications

    • Web browsers


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