Program Management/Programs/Telemetry/Probe Implementation

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Questions to answer

The complete list of questions can be found in the Platform roadmap.

The current focus questions are:

  • How fast can we load and render web pages?
  • How fast can we start up?
  • How fast can we react visually to people’s mouse movements and button presses?



A11y - David Bolter

Our Telemetry tracker is bug 648121. If we could get overall numbers for page load etc. I'd like to compare the numbers for when a11y happens to be instantiated (we already probe for a11y instantiation).

Audio/Video - Robert O'Callahan

  • Audio/Video doesn't really affect the above questions.

DOM - Johnny Stenback

We have some telemetry probes in place already, notably cycle collector related ones and mutation event related ones. The pending work at the point of this writing is tracked in the following bugs:

Graphics - Jeff Muizelaar

The big one here is paint time. We should aim to never go above 16 ms. The paint time is the lower bound on any perceived responsiveness. bug 694014.

JS - Dave Mandelin

Layout - Jethro Villegas

Mobile - Brad Lassey/Doug Turner

Network - Josh Aas

We have a simple probe for measuring page load time. There is just a single one, not recognizing network environment, content size, resource per page count etc.

It is roughly the time between a link load start (enter key in the address bar or mouse release on link/bookmark) and invoke of onload event in the content (last received byte of a non-background content sub-resource).

Peak of the value seems to be around 1.051 second. However, this probe has a wide distribution. Graphs on doesn't provide any statistical analyzes, so it is hard to say what percentage of loads is within what time range. To note, there is a significant number of page load times even longer then 10s.

There is a bug to enhance this probe (695766).

We also have many probes for cache performance - how often we have a cache hit, how long it takes to open/clear/read from. There are plans to include even more cache-related probes.

Performance - Taras Glek

Nothing specific to do at this time.