4,786 research outputs found
Is the Web ready for HTTP/2 Server Push?
HTTP/2 supersedes HTTP/1.1 to tackle the performance challenges of the modern
Web. A highly anticipated feature is Server Push, enabling servers to send data
without explicit client requests, thus potentially saving time. Although
guidelines on how to use Server Push emerged, measurements have shown that it
can easily be used in a suboptimal way and hurt instead of improving
performance. We thus tackle the question if the current Web can make better use
of Server Push. First, we enable real-world websites to be replayed in a
testbed to study the effects of different Server Push strategies. Using this,
we next revisit proposed guidelines to grasp their performance impact. Finally,
based on our results, we propose a novel strategy using an alternative server
scheduler that enables to interleave resources. This improves the visual
progress for some websites, with minor modifications to the deployment. Still,
our results highlight the limits of Server Push: a deep understanding of web
engineering is required to make optimal use of it, and not every site will
benefit.Comment: More information available at https://push.netray.i
An Extremely Low-latency Congestion Control for Mobile Cellular Networks
Department of Computer Science and EngineeringSince the diagnosis of severe bufferbloat in mobile cellular networks, a number of low-latency congestion control algorithms have been proposed. However, due to the need for continuous bandwidth probing in dynamic cellular channels, existing mechanisms are designed to cyclically overload the network. As a result, it is inevitable that their latency deviates from the smallest possible level (i.e., minimum RTT). To tackle this problem, we propose a new low-latency congestion control, ExLL, which can adapt to dynamic cellular channels without overloading the network. To do so, we develop two novel techniques that run on the cellular receiver: 1) cellular bandwidth inference from the downlink packet reception pattern and 2) minimum RTT calibration from the inference on the uplink scheduling interval. Furthermore, we incorporate the control framework of FAST into ExLL???s cellular specific inference techniques. Hence, ExLL can precisely control its congestion window to not overload the network unnecessarily. Our implementation of ExLL on Android smartphones demonstrates that ExLL reduces latency much closer to the minimum RTT compared to other low-latency congestion control algorithms in both static and dynamic channels of LTE networks.clos
A First Look at Commercial 5G Performance on Smartphones
We conduct to our knowledge a first measurement study of commercial 5G
performance on smartphones by closely examining 5G networks of three carriers
(two mmWave carriers, one mid-band carrier) in three U.S. cities. We conduct
extensive field tests on 5G performance in diverse urban environments. We
systematically analyze the handoff mechanisms in 5G and their impact on network
performance. We explore the feasibility of using location and possibly other
environmental information to predict the network performance. We also study the
app performance (web browsing and HTTP download) over 5G. Our study consumes
more than 15 TB of cellular data. Conducted when 5G just made its debut, it
provides a "baseline" for studying how 5G performance evolves, and identifies
key research directions on improving 5G users' experience in a cross-layer
manner. We have released the data collected from our study (referred to as
5Gophers) at https://fivegophers.umn.edu/www20.Comment: Published at The Web Conference 2020 (WWW 2020). Please include WWW
in any citation
Understanding and Improving the Performance of Web Page Loads
The web is vital to our daily lives, yet web pages are often slow to load. The inefficiency and complexity of loading web pages can be attributed to the dependencies between resources within a web page, which also leads to underutilization of the CPU and network on client devices.
My thesis research seeks solutions that enable better use of the client-side CPU and network during page loads. Such solutions can be categorized into three types of approaches: 1) leveraging a proxy to optimize web page loads, 2) modifying the end-to-end interaction between client browsers and web servers, and 3) rewriting web pages. Each approach offers various benefits and trade-offs.
This dissertation explores three specific solutions. First, CASPR is a proxy-based solution that enables clients to offload JavaScript computations to proxies. CASPR loads web pages on behalf of clients and transforms every page into a version that is simpler for clients to process, leading to a 1.7s median improvement in web page rendering for popular CASPR web pages. Second, Vroom rethinks how page loads work; in order to minimize dependencies between resources, it enables web servers to provide resource hints to clients and ensures that resources are loaded with proper prioritization. As a result, Vroom halves the median load times for popular news and sports websites. Finally, I conducted a longitudinal study to understand how web pages have changed over time and how these changes have affected performance.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163157/1/vaspol_1.pd
SysMART Indoor Services: A System of Smart and Connected Supermarkets
Smart gadgets are being embedded almost in every aspect of our lives. From
smart cities to smart watches, modern industries are increasingly supporting
the Internet of Things (IoT). SysMART aims at making supermarkets smart,
productive, and with a touch of modern lifestyle. While similar implementations
to improve the shopping experience exists, they tend mainly to replace the
shopping activity at the store with online shopping. Although online shopping
reduces time and effort, it deprives customers from enjoying the experience.
SysMART relies on cutting-edge devices and technology to simplify and reduce
the time required during grocery shopping inside the supermarket. In addition,
the system monitors and maintains perishable products in good condition
suitable for human consumption. SysMART is built using state-of-the-art
technologies that support rapid prototyping and precision data acquisition. The
selected development environment is LabVIEW with its world-class interfacing
libraries. The paper comprises a detailed system description, development
strategy, interface design, software engineering, and a thorough analysis and
evaluation.Comment: 7 pages, 11 figur
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