FirefoxOS/Metrics/EngineeringMetrics

Engineering Metrics Engineering Metrics are part of Enhanced Telemetry (AKA Advanced Telemetry). This was introduced as part of the 2.5 release. In order for collection of these metrics to occur, the metrics.level setting must be set to 'Enhanced'. Engineering metrics are collected by Gecko in the form of histograms and shipped by the Gaia layer at regular intervals. They are collected on a per app basis.

The metrics that are currently collected (per app) include:

• Jank - The duration which a thread is blocked in ms.
• Reflow Duration - The duration a reflow takes in ms.
• Reflows - A count of the number of reflows.
• Security Category Errors - Security errors including
  • Mixed Content Blocker
  • Mixed Content Message
  • CSP
  • Invalid HSTS Headers
  • Invalid HPKP Headers
  • Insecure Password Field
  • SSL
  • CORS
• Errors - Number of errors triggered by a console.error call.
• Warnings - Number of errors triggered by a console.warn call.
• USS Memory - The USS memory consumed by an application. Note that this must be explicitly turned on in the HUD.
• Startup Times
  • Content Interactive - The duration in ms between application launch and the 'contentInteractive' performance mark.
  • Navigation Interactive - The duration in ms between application launch and the 'navigationInteractive' performance mark.
  • Navigation Loaded - The duration in ms between application launch and the 'navigationLoaded' performance mark.
  • Visually Loaded - The duration in ms between application launch and the 'visuallyLoaded' performance mark.
  • Media Enumerated - The duration in ms between application launch and the 'mediaEnumerated' performance mark.
  • Fully Loaded - The duration in ms between application launch and the 'fullyLoaded' performance mark.
  • Scan End - The duration in ms between application launch and the 'scanEnd' performance mark.
  • Content Interactive - The duration in ms between application launch and the 'contentInteractive' performance mark.