Operating system support for massive replication

Venkataramani, Arun; Kokku, Ravi; Dahlin, Mike

doi:10.1145/1133373.1133420

Cited by 3 publications

(6 citation statements)

References 17 publications

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“…Fairness: One way to improve fairness and avoid over-utilizing the connections of users who donate their access is to use rate limiting at APs or on clients, or to use cooperative transport protocols like TCP Nice [25] (appropriately tuned for wireless access).…”

Section: Fast Friendly Connection Establishmentmentioning

confidence: 99%

A measurement study of vehicular internet access using in situ Wi-Fi networks

Bychkovsky¹,

Hull²,

Miu³

et al. 2006

Proceedings of the 12th Annual International Conference on Mobile Computing and Networking

381

329

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The impressive penetration of 802.11-based wireless networks in many metropolitan areas around the world offers, for the first time, the opportunity of a "grassroots" wireless Internet service provided by users who "open up" their 802.11 (Wi-Fi) access points in a controlled manner to mobile clients. While there are many business, legal, and policy issues to be ironed out for this vision to become reality, we are concerned in this paper with an important technical question surrounding such a system: can such an unplanned network service provide reasonable performance to network clients moving in cars at vehicular speeds?To answer this question, we present the results of a measurement study carried out over 290 "drive hours" over a few cars under typical driving conditions, in and around the Boston metropolitan area (some of our data also comes from a car in Seattle). With a simple caching optimization to speed-up IP address acquisition, we find that for our driving patterns the median duration of linklayer connectivity at vehicular speeds is 13 seconds, the median connection upload bandwidth is 30 KBytes/s, and that the mean duration between successful associations to APs is 75 seconds. We also find that connections are equally probable across a range of urban speeds (up to 60 km/hour in our measurements). Our end-toend TCP upload experiments had a median throughput of about 30 KBytes/s, which is consistent with typical uplink speeds of home broadband links in the US. The median TCP connection is capable of uploading about 216 KBytes of data.Our high-level conclusion is that grassroots Wi-Fi networks are viable for a variety of applications, particularly ones that can tolerate intermittent connectivity. We discuss how our measurement results can improve transport protocols in such networks.

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Section: Fast Friendly Connection Establishmentmentioning

confidence: 99%

A measurement study of vehicular internet access using in situ Wi-Fi networks

Bychkovsky¹,

Hull²,

Miu³

et al. 2006

Proceedings of the 12th Annual International Conference on Mobile Computing and Networking

381

329

View full text Add to dashboard Cite

show abstract

“…In the following we give an outline of this analysis. The complete analysis with detailed proofs appears in the our technical report [49].…”

Section: Discussionmentioning

confidence: 99%

“…It is then straightforward to compute the total amount of Reno flow sent out in a period. We show in the technical report [49] that the interference I, defined as the fractional loss in throughput experienced by Reno flows because of the presence of Nice flows, is given as follows. The derivation of I indicates that all three design features of Nice are fundamentally important for reducing interference.…”

Section: Discussionmentioning

confidence: 99%

TCP Nice

Venkataramani

Kokku

Dahlin

2002

SIGOPS Oper. Syst. Rev.

Self Cite

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Many distributed applications can make use of large background transfers -transfers of data that humans are not waiting for -to improve availability, reliability, latency or consistency. However, given the rapid fluctuations of available network bandwidth and changing resource costs due to technology trends, hand tuning the aggressiveness of background transfers risks (1) complicating applications, (2) being too aggressive and interfering with other applications, and (3) being too timid and not gaining the benefits of background transfers. Our goal is for the operating system to manage network resources in order to provide a simple abstraction of near zero-cost background transfers. Our system, TCP Nice, can provably bound the interference inflicted by background flows on foreground flows in a restricted network model. And our microbenchmarks and case study applications suggest that in practice it interferes little with foreground flows, reaps a large fraction of spare network bandwidth, and simplifies application construction and deployment. For example, in our prefetching case study application, aggressive prefetching improves demand performance by a factor of three when Nice manages resources; but the same prefetching hurts demand performance by a factor of six under standard network congestion control.USENIX Association 5th Symposium on Operating Systems Design and Implementation

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“…In order to avoid network overhead, a partial prefetch scheme [15] and prefetching between proxies and dial-up clients [10] are presented. Recently, researchers propose to utilize the unused network bandwidth for prefetching with marginal effects on existing traffic [16,22], which makes Web prefetching more practical. The space overhead of building predictor trees can also been reduced by considering the specific access patterns [5].…”

Section: Introductionmentioning

confidence: 99%

“…¤ Prefetching requests will not increase the transmission time of regular requests. This is because (1) prefetching used for dynamic content does not consume additional network resources; and (2) a new TCP/IP protocol has been proposed [22] to avoid network resource competition between background traffic and existing traffic.…”

Section: Introductionmentioning

confidence: 99%

Accurately modeling workload interactions for deploying prefetching in Web servers

Cheng

Zhang

2003

2003 International Conference on Parallel Processing, 2003. Proceedings.

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Although Web prefetching is regarded as an effective method to improve client access performance, the associated overhead prevents it from being widely deployed. Specifically, a major weakness in existing Web servers is that prefetching activities are scheduled independently of dynamically changing server workloads. Without proper control and coordination between the two kinds of activities, prefetching can negatively affect the Web services and degrade Web access performance. In this paper, we first develop an open queuing model to characterize detailed transactions in Web servers. Using this model, we analyze server resource utilization and average response time with different request arrival rates when prefetching is involved under different kinds of Web services. Guided by this model, we then design a responsive and adaptive prefetching scheme that dynamically adjusts the prefetching aggressiveness in Web servers. Our scheme not only prevents the Web servers from being overloaded, but it can also minimize the average server response time. We have effectively implemented this scheme on an Apache Web server. Our measurementbased performance evaluation shows our model can accurately predict the utilization of Web server resources and the correspondent average response time.

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Operating system support for massive replication

Cited by 3 publications

References 17 publications

A measurement study of vehicular internet access using in situ Wi-Fi networks

A measurement study of vehicular internet access using in situ Wi-Fi networks

TCP Nice

Accurately modeling workload interactions for deploying prefetching in Web servers

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