Mind the delay: the adverse effects of delay-based TCP on HTTP
Mind the delay: the adverse effects of delay-based TCP on HTTP
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DOI：
10.1145/3386367.3431299
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
Neil Agarwal;Matteo Varvello;Andrius Aucinas;F. Bustamante;R. Netravali
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文献类型：
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作者：
Neil Agarwal;Matteo Varvello;Andrius Aucinas;F. Bustamante;R. Netravali
在过去的三十年中，Web和网络协议中有很大的发展：其中，从HTTP/1.1到HTTP/2的过渡以及从基于损失的TCP拥塞控制算法转变。本文认为，这两种趋势彼此之间是矛盾的，最终损害了网络性能。使用对照合成研究，我们展示了基于延迟的拥塞控制方案（例如BBR和Cubic +混合慢速启动）如何导致移动网络中可用的拥塞窗口的低估，以及该如何显着缩减HTTP/2的有效性。为了量化当前网络中这种发现的影响，我们以两种方式发展了Web Performance工具箱。首先，我们开发了Igor，这是一种客户端的TCP拥塞控制检测工具，可以通过在缓慢启动过程中专注于其行为来区分基于损失和基于延迟的算法。其次，我们开发了一个铬片，该铬片可以在每个域中使用HTTP版本的细粒度控制。使用这些新的Web性能工具，我们分析了300多个真实网站，发现仅依靠基于延迟的拥塞控制算法的67％的网站使用HTTP/1.1具有更好的性能。
The last three decades have seen much evolution in web and network protocols: amongst them, a transition from HTTP/1.1 to HTTP/2 and a shift from loss-based to delay-based TCP congestion control algorithms. This paper argues that these two trends come at odds with one another, ultimately hurting web performance. Using a controlled synthetic study, we show how delay-based congestion control protocols (e.g., BBR and CUBIC + Hybrid Slow Start) result in the underestimation of the available congestion window in mobile networks, and how that dramatically hampers the effectiveness of HTTP/2. To quantify the impact of such finding in the current web, we evolve the web performance toolbox in two ways. First, we develop Igor, a client-side TCP congestion control detection tool that can differentiate between loss-based and delay-based algorithms by focusing on their behavior during slow start. Second, we develop a Chromium patch which allows fine-grained control on the HTTP version to be used per domain. Using these new web performance tools, we analyze over 300 real websites and find that 67% of sites relying solely on delay-based congestion control algorithms have better performance with HTTP/1.1.