1 maximizing remote work in flooding-based p2p systems qixiang sun neil daswani hector garcia-molina...
Post on 20-Dec-2015
216 views
TRANSCRIPT
1
Maximizing Remote Work in Flooding-based P2P Systems
Qixiang Sun
Neil Daswani
Hector Garcia-Molina
Stanford University
4
Problem
• Accept new queries from local clients• Handle remote queries from other super-nodes
Where is the balance?
?
5
Problem (2)
• Objective: Remote Work – process as many queries from other nodes as
possible.
Query
0 11
1
0 0
7
Simple Model
Super-nodes operate in rounds
Capacity C
Accepts new queriesfrom local clients
Handles remote queries
8
When Overloaded
• Choose queries with the highest TTL first
• Ties can be broken randomly
Has a steady state and
is optimal in remote work
?
17
Example
• Star topology with TTL = 1
Identical = 0.5Remote work = 3.5 C
Different Remote work = 6 C
1
0 0
0
0 0
0
18
Penalty of using identical
. . . . . .D1 i nDD
Maximum remote work is at most n C
Pick = all nodes saturatedD1
1
penalty is D
1
1
D1
1 remote work = n C (1 - )
19
Penalty of using identical (2)
D
1
1• How big is ?
D1 TTL + 1
D1 50 penalty is less than 2%
In practice:
20
Solving for different
1
0 0
0
0 0
0
Similar to findingthe dominatingset for the graph
w1 w2
w3
w4
Minimize sum of all weights
22
Future Directions
• Nodes of different capacities
• Incremental algorithm for computing at each node
• An incentive mechanism so that each node will forward neighbors’ queries