Characterizing and Mitigating Web Performance Bottlenecks in Home - - PowerPoint PPT Presentation

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Characterizing and Mitigating Web Performance Bottlenecks in Home - - PowerPoint PPT Presentation

Characterizing and Mitigating Web Performance Bottlenecks in Home Networks Srikanth Sundaresan, Nazanin Magharei, Nick Feamster Georgia Tech Renata Teixeira CNRS and UPMC Sorbonne Universits Sam Crawford SamKnows Broadband and the Web


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SLIDE 1

Characterizing and Mitigating Web Performance Bottlenecks in Home Networks

Srikanth Sundaresan, Nazanin Magharei, Nick Feamster

Georgia Tech

Renata Teixeira

CNRS and UPMC Sorbonne Universités

Sam Crawford

SamKnows

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SLIDE 2

Broadband and the Web

  • Broadband speeds are increasing

– Do applications get the benefit of higher speeds? Which factors affect Web page load time?

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SLIDE 3

Reducing page load time is important

  • Server side

– Make TCP work better: higher ICW – Newer protocols: SPDY

  • Network

– Move content closer: CDNs – Increase throughput – Reduce lookup time

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SLIDE 4

Web Performance Bottlenecks:

Throughput, latency, DNS, TCP overhead

Page load times are still high

Multiple seconds

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SLIDE 5

Outline

  • Characterizing Web Performance Bottlenecks

– Throughput bottlenecks – Latency bottlenecks

  • Analyzing benefit of acceleration techniques

from the home

– DNS caching – TCP connection caching – Content caching

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SLIDE 6

The Data

  • Collected from the FCC/SamKnows

deployment

– 11 ISPs, 5500 homes, 1 month

  • Web test client

– 9 popular sites – Up to 8 concurrent threads – Breakdown of lookup time, time to first byte, time to fetch objects

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SLIDE 7

Load time flat‐lines after 8 Mbits/s

Higher throughput does not always improve load time

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SLIDE 8

The access link is a bottleneck

  • Both throughput and latency affect load time

– Last mile latencies can exceed 40 ms – Increases load times by many times that number

  • Reducing impact of the last mile

– Apply acceleration techniques in the home!

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SLIDE 9

Outline

  • Characterizing Web Performance Bottlenecks

– Throughput bottlenecks – Latency bottlenecks

  • Analyzing benefit of acceleration techniques

from the home

– DNS caching – TCP connection caching – Content caching

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SLIDE 10

Experiment set up

  • Study impact of:

– DNS caching – TCP connection caching – Content caching

  • Web client fetches objects serially

– curl, dnsmasq, polipo

  • BISmark test bed

– 27 homes, 13 days

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SLIDE 11

Summary of Results

  • Any sort of caching helps!

– DNS caching saves 10‐200ms – Connection caching saves 100ms‐1s+ – Content caching saves 100ms‐1s+ over connection caching

  • Improvements depend on site characteristics

– Server location, number of domains – Number of objects – Cacheability of DNS records, content

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SLIDE 12

Relative impact of different schemes

Impact varies across sites, but connection and content caching offer significant benefits

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SLIDE 13

Is it better than ISP‐edge caching?

Improvement in load time by caching in home vs nearby server

Optimizations in the home have significant impact

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SLIDE 14

Future Work

  • Implement system to do “popularity based”

caching

– Pre‐fetch popular DNS domains – Keep connections open to popular Web sites

  • Initial implementation on BISmark router

– Understand potential improvement over end‐host implementation

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SLIDE 15

Conclusion

  • Latency becomes major bottleneck at higher

throughput

  • Network‐side optimizations help, but last‐mile

presents fundamental problem

  • Moving standard optimizations inside the

home results in major improvements

srikanth@gatech.edu