Brief Announcement: Stretch Between Nearby Peers

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Brief Announcement Stretch Between Nearby Peers

• Kirsten Hildrum
• John Kubiatowicz
• Jeremy Stribling

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Object Location
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Behind the Cloud
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Well-Placed Objects
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Stretch

• Stretch is ratio of distance traveled to distance
  to closest copy
• Getting low stretch is
• easy when objects are distant
• hard when objects are nearby

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Low Stretch Systems(including rings)
destination
Country
State
City
Physical distance is distance on this line.
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Some pairs very bad!
Country
State
City
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Fixable
Level 3
Level 2
Level 1
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Reality matches thought experiment

• Histogram of stretch for nearby pairs on a
  simulated transit-stub graph
• Matches thought experiment on line
• Fixes do help!

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Conclusion

• Low stretch to nearby objects is harder than low
  stretch to distant objects
• If many accesses are to nearby objects, must to
  consider stretch to nearby objects
• Can get low stretch, but cost may be too high to
  be reasonable
• Related to HSTs (Hierarchically-well Separated
  Trees)