Odyssey Agile Application Aware Adaptation for Mobility Kip Walker some slides borrowed from Satya 15 213 Research Overview Talk Odyssey 1 A Glimpse of the Future Imagine you are a tourist in Paris with a wearable computer wireless access to remote services unobtrusive heads up display microphone earphones speech for computer interactions online language translation Let s go 15 213 Research Overview Talk Odyssey 2 What Makes This Science Fiction Lack of hardware NO We have what we need Lack of applications Nope we have those too Need a system capable of coping with the problems of mobility Odyssey to the rescue 15 213 Research Overview Talk Odyssey 3 Problems with Mobility Mobile elements are resource poor relative to static elements of same era weight power size constraints Mobility leads to communication uncertainty enormous variation in bandwidth latency intermittent connectivity Power management is a concern actions may have to be slowed or deferred communication costs energy need to rely on resources of remote servers but may not be able to reach them 15 213 Research Overview Talk Odyssey 4 Adaptation Make mobile clients more robust by offering adaptation rely on servers when possible function autonomously if needed monitor and adjust to current conditions 15 213 Research Overview Talk Odyssey 5 Adaptive Applications applications consume resources network bandwidth CPU cycles battery power disk space resources are variable so applications adapt use of resources as resource quality changes 15 213 Research Overview Talk Odyssey 6 Goals Support variety of applications and data types Concurrent applications Quick adaptation Simple programming model 15 213 Research Overview Talk Odyssey 7 Who Controls Adaptation The Operating System Individual applications Both Application Aware Adaptation 15 213 Research Overview Talk Odyssey 8 What Knobs Do We Have Where work gets done let powerful remote servers do the work How snazzy the data is Fidelity degrade data meaningfully before giving to mobile host has many dimensions one is universal consistency others depend on data type movies frame rate frame quality geographical databases feature set minimum feature size tradeoffs are application dependent 15 213 Research Overview Talk Odyssey 9 Cutting to the chase We built a prototype runs on several UN X platforms logically an OS extension provides a small API to applications Implementation follows directly from the high level design need data type aware components to offer fidelity choices need a central piece to watch the resources network etc 15 213 Research Overview Talk Odyssey 10 Viceroy and Wardens System level data differentiation through wardens specialized code components a la device drivers provides system level support to manage a data type trusted entities unlike applications Wardens subordinate to viceroy single central component type independent system level support responsible for all resource allocation arbitration central point of authority and control for Odyssey 15 213 Research Overview Talk Odyssey 11 Client Structure Viceroy Odyssey Application All sys tem NetBSD OS Kernel 15 213 Research Overview Talk Upcall ca lls Warden3 Warden2 Warden1 c al y se s y Od ls Interceptor Odyssey 12 Resource Negotiation Applications give viceroy a window of tolerance for some resource viceroy monitors resource availability if it leaves window notifies application via upcall Fid 1 Fid 2 Fid 3 Fid 4 Available bandwidth Our architecture supports many resources we currently focus only on network bandwidth 15 213 Research Overview Talk Odyssey 13 Applications Video server offers movie at several levels of fidelity application plays the track that the current bandwidth can support xanim split into client and server WWW distillation server degrades data before shipping to client images can be compressed HTML can be summarized Netscape client side proxy remote distillation server Speech Recognition local remote hybrid execution Janus support remote recognition method hybrid 15 213 Research Overview Talk Odyssey 14 Evaluation don t blink Application aware adaptation is superior to static strategies applications are able to attain desired performance movie doesn t drop frames web delays are masked by compression speech recognition always available Centralized resource management outperforms alternatives all applications come closer to meeting performance goals Agility needs improvement 15 213 Research Overview Talk Odyssey 15 Future Work Short term adaptation for Web objects other than images improving agility on bandwidth drops support for unified cache managment Medium term explore integration of Odyssey in other operating systems broaden number of managed resources enlarge range of supported applications Long term deploy Odyssey for real use dynamic function vs data shipping as in speech 15 213 Research Overview Talk Odyssey 16 Conclusion Need for adaptation in mobile systems is widely recognized Application aware adaptation offers most general and effective approach to adaptation collaborative partnership between system and application previous approaches are limiting cases of this approach Odyssey prototype provides initial validation of concept 15 213 Research Overview Talk Odyssey 17 Contributors to Odyssey Primary contributors Jason Flinn Dushyanth Narayanan Brian Noble M Satyanarayanan Eric Tilton Kip Walker Numerous secondary contributors involved in Coda Janus NetBSD Trace Modulation etc etc etc 15 213 Research Overview Talk Odyssey 18
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