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Leveraging Smart Phones to Reduce Mobility Footprints

Presented by Michael Fusaro

Stephen SmaldoneLiviu Iftode

Benjamin GilbertMahadev Satyanarayanan

Nilton BilaEyal de Lara

Rutgers University Carnegie Mellon University University of Toronto

[email protected]@cs.rutgers.edu

[email protected]@cs.cmu.edu

[email protected]@cs.toronto.edu

Worcester Polytechnic Institute

Mobility Footprint• Definition

o the size, weight, energy demands of hardware that is needed to maintain an effective mobile computing environment

• Mobile computing utopiao Zero or little footprinto Ideal performance, safety, and reliabilityo Perfect re-creation of computing environment

anywhere


Mission Impossible?• Harness virtual machine technology

• Encapsulate personal computing state in a VM

• Deliver VM over the Internet to a local PC

• Resume execution


The Internet Suspend/Resume® (ISR) project

• Project at CMU

• Professor M. Satyanarayanan in charge of the projecto Also developed the Andrew File System

• Cuts the tight binding between PC state and PC hardware

• Layers virtual machines on top of a distributed file system

• Assumes large amounts of bandwidth are available

• Resilient against high network latency and jitter


Problem: Oases of Connectivity


Horatio to the Rescue!• A localized, self-cleaning portable cache for VM state

• ISR user suspends state to Horatio instead of ISR servero Can also resume from it

• Opportunistically synchronizes state with the ISR server

• Designed to be run primarily on smart phones

• Any mobile device can be usedo Need lots of storageo Good connectivity optionso Good computational abilities


Design of Horatio• Operates within the ISR environment

• Parcelo The VM-encapsulated environment

• Each parcel has 2 distinct partso Data state The encrypted VM image itself

o Control state Encryption keyring, configuration information and ownership

nonce

• Nonce: cryptographic lock

• Separation of control and data important for simplifying replication and parallelism abilities.


Where does Horatio Fit In?


Design of Horatio II• Ownership nonce

o Exclusive lock representing ownership of a parcel

• Granted when a parcel is "checked out" of ISR server

• Required when a parcel is "checked in"

• Only 1 site can own a parcel at any point Client Server Horatio


Reducing Latency• The VM can be suspended to

Horatio instead of the server

• Horatio will choose the best available connectivity option

o Ethernet, USB, WiFi, 3G, etc.

o Saves time: more bandwidth between Horatio and client

• The VM can be resumed from Horatio as well


Optimizations• Self-cleaning

1. Horatio device granted ownership of a parcel• Immediately begin writing "dirty" data to ISR server

• Concurrent uploadso Both Horatio and the ISR client can upload VM state at the same

time

• Memory Image Diffs o Send the deltas instead of complete copy of memory image at

each check-in

• Eager state propigationo Speculatively send altered disk and memory chunks to Horatio

device in the background


System Evaluation• Microbenchmarks

o Synthetically generated parcel state

• Macrobenchmarkso Scripted workloads generate parcel state


Microbenchmark Results


Macrobenchmark Results


Self Cleaning & Eager Propagation

State sizes in MB

Self cleaning times in seconds


Future Work

• Network stack needs improvement on some smart phones

• Resume location prediction

• Scale Horatio to work with future Internet bandwidths


Conclusions

• Resume times reduced by up to 98%

• Suspend times reduced by up to 97%

• Opportunistic self-cleaning mechanism works well


Questions?


References• Leveraging Smart Phones to Reduce Mobility Footprints. Stephen

Smaldone, Benjamin Gilbert, Nilton Bila, Liviu Iftode, Eyal de Lara, M. Satyanarayanan International Conference on Mobile Systems, Applications, and Services (MobiSys), Kraków, Poland, June 2009.

• The Internet Suspend/Resume (ISR) project. 10 April 2011. <http://isr.cmu.edu/>

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