Turducken: Hierarchical Power

Management for Mobile DevicesJacob Sorber, Nilanjan Banerjee,

Mark Corner, Sami Rollins

University of Massachusetts, Amherst

Presentation prepared by: Kip Coonley

Paper appears in “Proceedings of the Third International Conference on Mobile Systems, Applications, and Services” (MobiSys 05), Seattle, WA, USA, June, 2005

Additional figures from www.cs.dartmouth.edu/~sorber/slides/mobisys2005slides.ppt

Key issue: Battery Lifetime vs. Mobility

Scenarios and photos care of Nilanjan Banerjee www.csce.uark.edu/~nilanb/

Scenario 2 Scenario 3

Key question: Which device to use?

laptop phone Mote

Scenario 1

40W

2W

0.04WSensor

PDA

Laptop

Simple computationand storage

Download Web Pages

Very complex computation

Send/RecvMail

Tasks requiringlarge memory or storage space

Pow

er N

eeds

Choosing the right device for the job

Wake-On-Wireless [Shih, et al]Low-power radio receives wakeup messagesRequires in-network supportFocus on when to wake up

Possible Solutions (Related Work)

WiFi Power Save Mode (PSM)

Local Availability of dataStaleness issue

Battery technologyEnergy scavenging

Wireless optimizations [Anand, et al], Disk Spindown [Helmbold, et al], Multiple radios [Pering, et al], Multiple processor cores [Mayo & Ranganathan]none provide orders-of-magnitude scaling of

power

A New Approach: Turducken – 3 devices in 1

WiFi detector

Mica2 Mote

PDA

Laptop

Example: Mote checks for a network, PDA checks for mail server,Laptop remains asleep until user reads the mail

• Integrate multiple independent platforms

• Pass control between tiers• Suspend unneeded tiers

The Idea: Hierarchical Power Management

Reducible Power – Power that can be eliminatedReducible vs. Non-Reducible Power

Non-reducible Power – Required for computation

• LCD Screen, Wireless power, Caching

• Power supply, On-board oscillators, Memory, I/O buses, Voltage & Current regulation

• Time SynchronizationCan be completely performed by the moteLowest tier periodically synchronizes with remote time

server• Web Prefetching

More complicated application which requires at least PDAMote detects wireless networksPDA periodically fetches updates to frequently accessed

pages• E-Mail

Involves user interactionBoth incoming and outgoing updatesLaptop accesses mail via proxy on the PDA

3 Applications

• Laptop• Laptop+Mote• Laptop+PDA+Mote

3 ConfigurationsA Tiered Approach

PDALaptop MoteUSB RS-232

Wake

Note on Methodology: Time dilation used to extrapolate data

• Power Draw Comparisons of Turducken Tiers

• Wakeup Interval vs. Lifetime for Integrated Turducken System

• Availability of Wireless Networks and its impact on the Turducken System

3 Experiments

Laptop Laptop+Mote

Full Turducken

Power-By-Tier

Wake Synchronization Time of Device

Time SynchronizationMote is the right device for the jobLaptop & PDA always suspended

Wake Synchronization Time of Device

Web Caching5MB storage = 15 websites cached

For always-on operation, Turducken lasts up to 10 times longerWaking every 6 minutes, Turducken lasts 3 times longer

Wake Synchronization Time of Device

E-MailLaptop wakes 2 min every hr, 4MB of mail stored

Due to laptop user input, overall system lifetimes much lessFor waking every 6 minutes, Turducken lasts 1.5 times longer

Availability of Wireless Network(Web caching only, 12 minute wake interval preset)

Probability of WiFi

Life

tim

e (h

ours

)

With no network, mote prevents laptop from wakingTurducken performs well over a variety of connectivity patterns

Conclusions & Thoughts• Turducken extends laptop lifetime up to

10x (Always-on)!• Where Turducken Wins - Laptop on > 17

min/hr

• Hierachical Power Management & Reducible vs. Non-Reducible Power

• Sleep/Wake power costs – this work averages

• Device portability/weight integration of tiers

• Device reliability with integration of tiers

Turducken: Hierarchical Power

Management for Mobile DevicesJacob Sorber, Nilanjan Banerjee,

Mark Corner, Sami Rollins

Paper appears in “Proceedings of the Third International Conference on Mobile Systems, Applications, and Services” (MobiSys 05), Seattle, WA, USA, June, 2005

One more experiment: Reachability of Wireless Network(Web caching only, 12 minute wake interval preset, always available)

Similar results to Availability of WiFi except…Mote cannot access WiFi -only detect it - PDA must work more