phpied.com

Very rough notes from the event that just ended a few minutes ago

======== 1 ========

Tony Gentilcore (google) and Anderson Quach (MSFT) talked about the W3C working group and the specs for measuring performance:

• Navigation timing spec - HTML document: DNS, handshakes, load events
• Resource timing - how long JS, CSS, audio, video... take
• User timing - interactions, such as clicking a link

Challenges: user security, privacy. Small overhead for browsers. Useful actionable data out.

Navigation timing:

• window.performance - IE9 has no vendor prefix
• otherwise window.webkitPerformance
• FF4 probably shipping it too

Properties:

window.performance.timing
  .domainLookup
  .connect
  .domContentLoaded
  .loadEvent
  ....etc

Specs: http://test.w3.org/webperf/specs/NavigationTiming/

Resource Timing spec - upcoming

foreach resource 
  redirect
  fetchStart
  fetchEnd
  ...

User Timing - upcoming

  mark('pagelet')
  mark('something-else')
  ...
  
  >>> getMarks();
  {
    'pagelet': 123456767
  }

Stretch goals:

• painting times
• CPUs
• visibility (is the page in a background tab)
• allow real yealding setTimeout(0)
• don't animate faster than the browser paints

mailto: public-web-perf@w3c.org

======== 2 ========

Above the Fold Time: Measuring Web Page Performance Visually
Speaker: Jake Brutlag
Help from: Zoe Abrams, Pat Meenan (webpagetest) Google

What the user perception of page load timing is.

AFT (Above the Fold Timing) algo
AFT: When content above the fold stops changing and reaches its final state

Integrated in WebPageTest.org

Motivation

• AFT more representative than DOMContentLoaded or onload
• onload - different in IE and FF, e.g. async scripts block onload or not

Method:

• video capture
• AFT cutoff time - upper bound, e.g. 45 sec for DSL
• split pixels into static and dymanic (ads)
• AFT = latest change of a static pixel

Magic number - 5 determined empirically
static pixels are those that change less than 5 times

Application - validate other metrics, cross-browser, visual
Limitation - lab only

{I ran webpagetest.org on facebook.com with AFT on.
The results are very close to onload, as expected.
It's a simple page. Results:

http://www.webpagetest.org/result/110315_P9_5MDJ/

}

== break ==

Note from the sponsor StrangeLoop: a downloadable "State of the Union"
A study of top 2000 Alexa retail sites. Findings:

1. 11.2 sec onload avg
2. top 100 sites slower than the lower ranked
3. those using CDNs are not faster
4. failed to implement the basics - YSlow stuff

======== 3 ========

Next-gen YSlow
Betty Tso and Marcel Duran, Yahoo!

YSlow for Chrome last week
Not as accurate as Firefox cause headers, timing come from:
1. Crawl DOM
2. x-domain requests

Announcing YSlow bookmarklet version
for mobile and all other browsers to be released early april
YSlow now on Git?

Lots coming up, e.g:

• Multi-language support
• HAR-to-YSlow
• YSlow export to JDrop

Bookmarket works like:
1. crawl DOM
2. Use YQL to get headers

     SELECT * FROM data.headers WHERE
      url IN ('http://...', 'http://...')

======== 4 ========

Visibility into Mobile Performance
Steve Souders, Google

Demo #1: http://blaze.io/mobile/
WebPageTest.org framework connected to iPhone and Android apps
Mobile waterfalls
Demo #2: pcapperf
1. setup wifi hotspot on a pc/mac
2. tcpdump to capture .pcap file
3. upload .pcap to http://pcapperf.appspot.com app
4. observe waterfall via pcap2har and harviewer
5. run pagespeed on the har
Demo #3: JDrop
http://jdrop.org
Upload JSON so you can run something on mobile and view/analyze results in desktop's large screen
Works with the bookmarklet tools part of Steve's package of mobile meta-tool

This entry was posted on Tuesday, March 15th, 2011 and is filed under performance, tools. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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