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Computational Energy Cost of TCP CS294-14 Paper Discussion Fall 2007

Computational Energy Cost of TCP CS294-14 Paper Discussion Fall 2007. 2007-10-17 Yanpei Chen. Paper Overview. To measure energy of TCP over wireless Energy given by current drawn through multimeters Platforms running TCP during measurement

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Computational Energy Cost of TCP CS294-14 Paper Discussion Fall 2007

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  1. Computational Energy Cost of TCPCS294-14 Paper Discussion Fall 2007 2007-10-17 Yanpei Chen

  2. Paper Overview • To measure energy of TCP over wireless • Energy given by current drawn through multimeters • Platforms running TCP during measurement • TCP run on laptop w/ FreeBSD 4.2 & 5 (TCP reno & newreno) • iPAQ (TCP reno) • Results • Kernel-NIC copy is costly: 60-70% energy • User-kernel copy cost 15% energy • TCP processing 15% energy – can be further broken down • Suggested energy reduction techniques • Zero-copy: Data from user space directly to NIC • More powerful NIC to reduce kernel-NIC copy cost • Save 20-30% energy

  3. Related Work • Most energy work done on wireless interface, channel environment etc. • Past work on TCP computational cost focus on time consumed • One past work on TCP energy – consumption not broken down • Contributions of the paper • Help develop energy reduction techniques • Develop TCP energy models • Allow NS-2 to simulate energy cost • Present energy measurement method … to be reused …

  4. Methodology • Instrumentation • Arithmetic • Graphical illustration

  5. Results • Average total energy • TCP vs. Radio • Comparison against time metric • Breaking down TCP energy cost

  6. Results – Breaking down TCP processing cost • Check sum cost by running check sum code • TO, TD, ACK cost in lossy network • Validate results by predicting energy use for 10MB of data

  7. Energy reduction techniques • Zero-copy: Data from user buffers directly to NIC • Function exists in FreeBSD 5 • More powerful NIC to reduce kernel-NIC copy cost • Keep TCP send buffer on NIC • Maximize data transfer chunk from kernel to NIC • Save 20-30% energy

  8. Questions • Have their work made its way into NS-2? • Similar work on wired topology?

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