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
Reducing the Energy Usage of Office Applications
Eyal de Lara
Dan S. Wallach
Carnegie Mellon University
Can this work without source code?
Middleware-based proxy can help!
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 proxy parses and transcodes documents
Client proxy uses external API to interact with PowerPoint
How much energy can component-based adaptation save?
Uses well-defined data formats, exported APIs
Digital multimeter samples laptop power use
Applications mark start and end of events
Energy usage is integral of power over time
Benchmark consists of 10 PowerPoint presentations
Size and effect of distillation vary
Average energy usage reduced 40%!
With simple filter, energy usage reduced 49%!
Distillation reduces paging energy 13%
Benefit less on subsequent traversals of document
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!
Average energy reduction of 11%
Mystery: Why does Puppeteer take less time and energy to load a presentation than native mode?
Verified this hypothesis by measuring:
With 64 KB buffers, native mode uses 26% less energy
Disabling power management saves additional 18%
Disk spinning = Wasted Energy
Disk power management predicts periods of inactivity
After autosave, waits for additional activity
Disk in high-power state for 30 seconds
Transparent power management can help!
Transparent power management
Puppeteer provides a mechanism for achieving reductions
Other potential domains for this work: