How much does caching help caching eliminates 80 web

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Unformatted text preview: progression of page load webpagetest tool for hfp://coursera.org (Firefox, 5/1 Mbps, from VA, 3/1/13) 157 Modern Web Pages (2) Yikes! - 23 requests - 1 Mb data - 2.6 secs webpagetest tool for hfp://coursera.org (Firefox, 5/1 Mbps, from VA, 3/1/13) 158 30 11/26/13 Modern Web Pages (3) Yay! (Network used well) •  Waterfall and PLT depends on many factors –  Very different for different browsers –  Very different for repeat page views –  Depends on local computa8on as well as network 159 Recent work to reduce PLT Pages grow ever more complex! –  Larger, more dynamic, and secure –  How will we reduce PLT? 1.  Tools to study page load process 2.  Befer use of the network –  HTTP/2 effort based on SPDY 3.  Befer content structures –  mod_pagespeed server extension 160 31 11/26/13 Page load is cri.cal, but o=en slow •  Amazon can increase 1% revenue by decreasing page load 8me by 0.1s. A few top pages take Median page load more than 10 seconds 8me is 3 seconds. to load. Many techniques aim to optimize page load time •  Best prac8ces: JaveScript/CSS placement, Image minifica8on, … •  Server placement: CDNs •  Web pages and cache: mod_pagespeed, Silo •  TCP/DNS: TCP fast open, ASAP, DNS pre- resolu8on, TCP pre- connect …, but op.miza.ons don’t always work. 32 11/26/13 …because , page load boflenecks are not well understood. •  Page load process is not strictly streamlined •  Page load ac8vi8es are inter- dependent, leading to boflenecks Dependency example <html> <script src="b.js"></script> <img src="c.png"/> </html> <html> <img src="c.png"/> <script src="b.js"></script> </html> html html HTML depends on JS comple8on b.js c.png HTML does not depend on image loads c.png b.js 33 11/26/13 Example: Dependency and boFleneck Possible op8mi...
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This document was uploaded on 04/04/2014.

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