an adaptive video multicast scheme for varying workloads
DESCRIPTION
An adaptive video multicast scheme for varying workloads. Kien A.Hua, JungHwan Oh, Khanh Vu Multimedia Systems, Springer-Verlag 2002. Outline. Introduction Related Work Proposed Approach Performance Model Performance Conclusion. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
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An adaptive video multicast An adaptive video multicast scheme for varying workloadsscheme for varying workloads
Kien A.Hua, JungHwan Oh, KhanKien A.Hua, JungHwan Oh, Khanh Vuh Vu
Multimedia Systems, Springer-Verlag 2002Multimedia Systems, Springer-Verlag 2002
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OutlineOutline
• Introduction
• Related Work
• Proposed Approach
• Performance Model
• Performance
• Conclusion
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IntroductionIntroduction
• Maximize the efficiency of server resource with– Periodic broadcast – Scheduled Multicast (batching)– Hybrid Design
• Will show that existing scheduled multicast techniques are not suited for hybrid designs
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Related WorkRelated WorkSkyscraper Broadcasting SchemeSkyscraper Broadcasting Scheme
• Fragmentation recursive function
– Series [1,2,2,5,5,12,12,25,25,52,52,…]
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Related WorkRelated WorkSkyscraper Broadcasting SchemeSkyscraper Broadcasting Scheme
Apply aforementioned series function => segment size = 10.4 !!
22-mins video
1.5 Mbits/sec
5 min buffer
0.5 min latency
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Related WorkRelated Work Scheduled Multicast Scheduled Multicast
• Differ primarily in the criterion used to select which batch will receive service– First come, first served (FCFS)– Maximum queue length first (MQL)– Maximum factored queue length first (MFQ)
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Related WorkRelated Work Scheduled Multicast Scheduled Multicast
• FCFS
• MQL
timeVideo 1
timeVideo 2
time
timeVideo 2
Video 1
Fair , maybe bad throughput
Better throughput, maybe not fair
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Related WorkRelated Work Maximum factored queue length first (MFQ)Maximum factored queue length first (MFQ)
• Applying a discriminatory weighting factor to the length of the queue
• : video i length, : the request frequency of video i
• Schedule video with the largest value of
iq if
tqtq
q
f
qi
i
i
i
i
/
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Related WorkRelated Work Maximum factored queue length first (MFQ)Maximum factored queue length first (MFQ)
• d• d
Still not fair, because not average waiting time !!
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Proposed ApproachProposed Approach
• Adaptive Hybrid Approach (AHA)– With a novel scheduled multicast --“Largest aggregated waiting time first scheme” (LAW)
– And SB (skyscraper broadcast)
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LAWLAW
• Compare with MQL, it take account of the distribution of the request – With considering “aggregated waiting time”
m : the total number of pending requests for video i
ija : the arrival time of the jth request for video i
c : the current time
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LAWLAW
S1=128*5-(107+111+115+121+126)=60
S2=128*4-(112+119+122+127)=32
S1=128*5-(107+111+115+121+126)=60
Compute the sum of video i service latency
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Adaptive hybrid approachAdaptive hybrid approach
• With following procedures to decide which videos to broadcast
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Adaptive hybrid approachAdaptive hybrid approach
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Performance modelPerformance model
• Compare AHA with MFQ-SB-n
• Performance metrics– Defection rate– Unfairness– Average service latency– Throughput
• 100 videos, each 120 mins,
avg. playback rate 1.5 Mbits/sec.
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Performance modelPerformance model
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Performance - LAW vs. MFQPerformance - LAW vs. MFQ
Arrival rate : 8 req/min
Skew factor : 0.3
LAW perform slightly better than MFQ
in service latency,throughput, defection rate
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PerformancePerformance
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PerformancePerformance
• Compare MFQ-SB-n with altering one of– Server Capacity (channels)– Request Arrival Rate– Skew Factor
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Alter Server Capacity Alter Server Capacity (channels)(channels)
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Alter Request Arrival RateAlter Request Arrival Rate
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Alter Skew FactorAlter Skew Factor
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Alter request rate & skew factorAlter request rate & skew factor
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ConclusionConclusion
• Prove that existing scheduled multicast schemes are not suited for hybrid design
• Proposed a new technique called Largest Aggregated Waiting time first (LAW)
• AHA is capable of coping with a changing workload
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Periodic Broadcast (1996)Periodic Broadcast (1996)
video
…
…
…
time
• PB v.s. batch:– Short initial delay– Large client-side buffer
Client requests
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Batching (1993)Batching (1993)
0 t1 t2 t3
Client requests
time
• Batch window:– The time interval to initiate a batch stream.
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Adaptive hybrid approachAdaptive hybrid approach
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Adaptive hybrid approachAdaptive hybrid approach