Bwdetail a bandwidth tester with detailed reporting
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BWdetail: A bandwidth tester with detailed reporting. Masters of Engineering Project Presentation Mark McGinley April 19, 2007 Advisor: Malathi Veeraraghavan

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Bwdetail a bandwidth tester with detailed reporting

BWdetail: A bandwidth tester with detailed reporting

Masters of Engineering

Project Presentation

Mark McGinley April 19, 2007

Advisor: Malathi Veeraraghavan

Acknowledgement: This work was carried out under the sponsorship of NSF ITR-0312376, NSF ANI-0335190, and DOE DE-FG02-04ER25640 grants.


Outline
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion


Problem statement
Problem Statement

  • Growing eScience traffic

Terabytes / month

ESnet Monthly Accepted Traffic, January, 2000 – June, 2006

Ref. 1


Problem statement1
Problem Statement

  • Scientific research efforts such as Atlas characterized by:

    • Large datasets

    • Geographically distributed collaborators

    • 1800 physicists, 150 universitiesand laboratories

  • Supporting high speed transfers of datasets often requires system tuning, diagnostics

[2]


Outline1
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion


Related work
Related Work

  • Iperf from NLANR

    • Successor to ttcp, similar to nttcp, nuttcp

  • Web100

    • Host system software (autotuning)

    • Lack of instrumentation/tools for diagnosing performance issues

  • Iperf100

    • Web100-based Iperf


Related work1
Related Work

  • Nettest

    • Incorporates Iperf

  • Net100

    • Leverages Web100 to eliminate “wizard gap” with autotuning

  • tcpdump



Related work3
Related Work

  • tcpdump


Related work4
Related Work

  • BWdetail



Outline2
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion


Overview of bwdetail
Overview of BWdetail

  • Bandwidth estimation ability of Iperf

  • Instrumentation capabilities similar to Web100, without kernel modification


Overview of bwdetail1
Overview of BWdetail

  • Software architecture

    • C program

    • TCP_INFO struct associated with each socket

    • Kernel parameters read/written using getsockopt(), setsockopt(), sysctl(), system()


Outline3
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion


Features and uses
Features and Uses

  • Data transfer for goodput estimation

    • Memory-to-memory is most common usage

    • Disk/memory-to-disk/memory

    • Memory transfer can either be a specific size or duration

    • Disk transfer using a file of specific size, to eliminate caching effects


Features and uses1
Features and Uses

  • Effect of caching

    • 1 GB disk-to-disk successive transfer


Features and uses2
Features and Uses

  • Multi-threaded client

    • Client uses separate threads to send data and monitor flow


Features and uses3
Features and Uses

  • Tunable parameters from command line

    • Socket buffer size

    • TCP congestion control algorithm

    • CTCP-enabled Web100 capable

    • SACK, Nagle, no metrics save


Features and uses4
Features and Uses

  • Adjustable reporting granularity

    • Client and server report goodput over some small, configurable interval (100ms)

    • Client reports cwnd, RTT, etc, every smaller, configurable interval (5ms)


Features and uses5
Features and Uses

  • Applications

    • Research regarding transport protocols

      • CTCP/Reno/BIC

      • Cwnd and RTT measurements

    • Improving performance on a path

      • Records relevant kernel parameters

      • Ongoing recording of cwnd, RTT, goodput

      • Change parameters, repeat


Outline4
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion



Outline5
Outline

  • Problem Statement

  • Related Work

  • Overview of BWdetail

  • Features and Uses

  • Demonstration

  • Conclusion


Conclusion
Conclusion

  • Available bandwidth estimation

  • Instrumentation such as cwnd without requiring kernel modification or privileged access


Thank you
Thank you

Questions?


References
References

  • [1] W.E. Johnston, ESnet4: Networking for the Future of DOE Science, http://www.es.net/ESnet4/ESnet4-Internet2Members-Dec-06-2006-1.ppt, Dec. 5, 2006

  • [2] The Atlas Experiment, www.atlas.ch


Limitations
Limitations

  • Does not replace tcpdump

    • tcpdump handles content

      • Needed to detect retransmissions, Ethernet PAUSE frames, verification

    • Incorporation of libpcap capabilities would degrade the non-interference status of BWdetail

      • BWdetail is interested in statistics, not content


Limitations1
Limitations

  • BWdetail does not replace an expert

    • Still requires knowledge to tune, does not provide autotuning

  • Use of TCP_INFO struct presents portability issues


Impact of monitoring
Impact of monitoring

  • Minimal, even at ~1 Gbps



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