Course Matters
description
Transcript of Course Matters
![Page 1: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/1.jpg)
Course Matters
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Recent Papers
from journals
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Good PostersBad Posters
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Improving I/O Performance of Intermediate
Multimedia Storage Node
Pal HalvorsenThomas Plagemann
Vera GoebelMultimedia Systems 03
![Page 5: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/5.jpg)
Problem
• Improve the performance of I/O in integrated multimedia storage node
• 3 areas of improvement are identified• reduce memory copy• checksum computation• FEC computation
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Reduce Memory Copy
• File system maintain pointer to an area in memory
• Communication system maintain pointer to same area in memory
• Memory copy avoided!
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Network Level Framing• Packet payloads are stored with
checksum• When packets are retrieved for sending,
destination address in header is updated• Checksum is updated with new
destination• No need to recompute checksum for
payload
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Integrated Error Management
• Data are stored on RAID-4 (single parity checks)
• Use the same error correcting code for RAID and packets
• Avoid multiple computation of error correcting code
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Experiment: Memory Copy
• Read 28662512B file 38 times in a loop
• The time to transmit data through the storage node is reduced by 45-50% when there is no CPU load, and by 70-73% when CPU load is high
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Experiment: Network Level Framing
• Transmit 255MB file• Time to calculate checksum is
reduced by 95-99%• Time spent in kernel is reduced
by 51-61%
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Experiment: Integrated Error Management
• With encoding FEC, the maximum throughput is 22-24 Mbps.
• Without encoding FEC, the maximum throughput is 1Gbps
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Let’s try again..
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Improving I/O Performance of
Intermediate Media Storage Node
Pal HalvorsenThomas Plagemann
Vera Goebel
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Contributions
• Improve performance by• reducing memory copy• reducing checksum computation• reducing ECC computation
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Reduce Memory Copy
• One shared copy of data for different OS component
dataFile
SystemNetworkSystem
Memory
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Network Level Framing
1
2
3
store payloadwith payload’s checksum
read payloadwith checksum
update header andchecksum
• Reduce time to packetize data and compute checksum for data
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Integrated Error Management
• Avoid multiple computation of error correcting code
data data data ECCRAID
ECC
reuse RAIDECC as ECCpacket
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Average Time to Transmit 1GB file from memory system under high CPU Load
0
50
100
150
200
250
300
1KB 2KB 3KB 4KBPacket Size
Tim
e (s
)
zero-copytraditional
Results: Zero Copy
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Results: Network Level Framing
UDP With NLF
0
2
4
6
8
1 2 4 8Packet Size (KB)
Tim
e (x
100
ms)
The RestChecksum
Traditional UDP
0
2
4
6
8
1 2 4 8Packet Size (KB)
Tim
e (x
100
ms)
Accumulated UDP Protocol Execution Time for sending 225MB file
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Results: Integrated Error Management
With ECC Encoding
Without ECC Encoding
22-24 Mbps 1 Gbps
Maximum Throughput with/without Encoding usingCauchy-based Reed Solomon Erasure Code
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Ad Hoc Networks
Session 1
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Mobile Ad Hoc Network
Radio
Router
Host
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Animation
• http://www-i4.informatik.rwth-aachen.de/~mesut/manet/manet_en.html
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Mobile Ad Hoc Network
RadioRouterHost
RadioRouterHost
RadioRouterHost
RadioRouterHost
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Examples
• Battlefield• Highway• Disaster Zone
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Challenges
• All the difficulties of wireless LAN• Plus• Nodes can move• Connections can go up/down• No fix route
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Two Papers
• IEEE JSAC • Special Issues in Wireless
Multimedia
• Baochun Li from U. of Toronto• Shiwen Mao from Polytechnic U.
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NonStop: Continuous Streaming Service on
MANET
Baochun Li IEEE JSAC 2004
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Streaming over MANET
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Network Partition Problem
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Only Solution ..
• Predict Partition• Replicate Service
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Partition Prediction
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Network Partition Problem
![Page 34: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/34.jpg)
How to Predict Partition?
• given velocity of each node• cluster nodes into “mobile
groups”• find mean group velocity
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Clustering Algorithm
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Clustering Algorithm
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Clustering Algorithm
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Clustering Algorithm
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Choosing Server
?
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How to Choose Server?
• find “stable group”• choose server within stable
group with the most similar velocity
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Stable Group
A B
mean <= radio rangeand variance is not too large
probability
distance
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Stable Group
A C
D
FG
H
E
B
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Stable Group
A C
D
FG
H
E
B
BCD are in my group
AGH are in my group
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Stable Group
A C
D
FG
H
E
B
BCDGH are in my group
ABDGH are in my
group
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How to Choose Server?
• find “stable group”• choose server within stable
group with the most similar velocity
![Page 46: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/46.jpg)
Summary
• Server construct mobile group by clustering nodes using velocity
• Use mean mobile group velocity to predict network partition
•Replicate service before partition to ensure continuous service
![Page 47: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/47.jpg)
Summary
• Node construct stable group by comparing distance over time
• Choose server within stable group with most similar velocity
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Multipath Transport and Multistream
Coding for MANET
Shiwen Mao et. al.IEEE JSAC
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Single Path Transport
![Page 50: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/50.jpg)
Multipath Transport
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Multipath Transport
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Video Coding: 1 of 3
I P P P P P P P
Typical Frame Dependency
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Video Coding: 1 of 3
II
PP
PP
PP
Multistream Coding
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Dynamic Reference Frame
• Choose last received frame as reference
believed to be received
![Page 55: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/55.jpg)
Predict Network States
GOOD :)
BAD :(
NACK ACK
![Page 56: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/56.jpg)
Example
0
1
2
3
4
5
6
7
ACK0 ACK2 ACK4
NACK1 NACK3 NACK5 ACK7
8
9
ACK6
10
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Video Coding: 2 of 3
I P P P
I P P P Base Layer
EnhancementLayer
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Video Coding: 2 of 3
S D
EL
BL
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Video Coding: 2 of 3
NACK
NACK
![Page 60: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/60.jpg)
Video Coding: 2 of 3
S D
BL
![Page 61: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/61.jpg)
Video Coding: 3 of 3
• Multiple Description Coding
![Page 62: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/62.jpg)
MDMC
• MDMC
+
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Example of MDMC
359 363 370
+7
Typical Reference Frame
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Example of MDMC
359 363 370
MDMC Reference Frame
![Page 65: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/65.jpg)
Example of MDMC
359 363 +9
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Example of MDMC
359 ? +9
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Example of MDMC
359 363 370
+9
361
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Example of MDMC
359 ? +9,+2
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Comparisons
Reference Frame
LayeredCoding
MDMC
Feedback
Buffer
Decoding Delay
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Improving Multicast
Session 2
![Page 71: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/71.jpg)
Organizing Multicast Receivers
Brian Neil Levine Sanjoy Paul
JJ Garcia-Luna-AcevesMultimedia Systems 03
![Page 72: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/72.jpg)
Retransmission in Mcast
![Page 73: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/73.jpg)
Idea
• Ask a neighbour for a missing packet
![Page 74: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/74.jpg)
“Helper” Tree
![Page 75: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/75.jpg)
Pick Helper By Hop
![Page 76: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/76.jpg)
Pick Helper by Hop
• Not entirely accurate• Need to consider latency, link
condition etc.
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Pick Neighbour By Latency
![Page 78: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/78.jpg)
Pick Helper by Latency
• How to measure latency?• unicast?• multicast?• shared-tree? per-source tree?
![Page 79: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/79.jpg)
Ideal “Location” of Helper
• share a common path, and is closer to source (“acceptable”)
![Page 80: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/80.jpg)
Idea
• Suppose node A and B know their path back to the source, then they can deduce if A is acceptable to help B
![Page 81: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/81.jpg)
MTrace
A B C
D
E
HG
F
I
![Page 82: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/82.jpg)
ERS
A B C
D
E
HG
F
I
my path is ABCDF
![Page 83: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/83.jpg)
ERS
A B C
D
E
HG
F
I
![Page 84: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/84.jpg)
Respond if
• acceptable• not too many helpee
![Page 85: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/85.jpg)
Picking Helper
• packet loss measurement
A B C
D
E
HG
F
I
30%
10%
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Maintenance
• Periodic refresh states (soft-states)
• Periodic repeat procedure
![Page 87: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/87.jpg)
Summary
• Organized receivers based on common path
• Enable peer-to-peer retransmission
![Page 88: Course Matters](https://reader036.fdocuments.in/reader036/viewer/2022062521/56814c04550346895db902d4/html5/thumbnails/88.jpg)
THE END