Performance/Metrics

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This page documents metrics from Performance Team services. Currently in Graphite.

Deployment and monitoring

See Performance/Runbook/Webperf services for the internal details of these services, such as where the metrics originate, and how they are processed/aggregated.

navtiming-2 metrics

The navtiming-2 metrics are available in Graphite under the frontend.navtiming2 prefix.

Difference with navtiming-1

Notable differences:

  • Offsets are computed relative to fetchStart instead of navigationStart.
  • We no longer filter out zero values.
  • The sanity filter no longer has an upper bound.
  • When the sanity filter encounters negative numbers, it rejects the entire event instead of just the individual data point.

See phab:T104902 for more information about why the metrics were redefined.

Offsets

  • responseStart: From PerformanceTiming, relative to fetchStart.
  • firstPaint: (non-standard)
  • domInteractive: From PerformanceTiming, relative to fetchStart.
  • domComplete: From PerformanceTiming, relative to fetchStart.
  • loadEventStart: From PerformanceTiming, relative to fetchStart.
  • loadEventEnd: From PerformanceTiming, relative to fetchStart. Also known as "Page load end" or "Total page load time". This typically corresponds with the browser's native page loading indicator.

Deltas

  • dns: Computed client-side from PerformanceTiming domainLookupEnd - domainLookupStart. (Transmitted as "dnsLookup")
  • unload: Computed client-side from PerformanceTiming unloadEventEnd - unloadEventStart.
  • redirect: Computed client-side from PerformanceTiming redirectEnd - redirectStart. (Transmitted as "redirecting").
  • mediaWikiLoad: Computed client-side based on custom mwLoadEnd and mwLoadStart measures. (Transmitted as "mediaWikiLoadComplete").
  • tcp: Computed server-side as connectEnd - connectStart. This includes SSL negotiation.
  • request: Computed server-side as responseStart - requestStart.
  • response: Computed server-side as responseEnd - responseStart.
  • processing: Computed server-side as domComplete - responseEnd.
  • onLoad: Computed server-side as loadEventEnd - loadEventStart.
  • ssl: Computed server-side as connectEnd - secureConnectionStart. This is a subset of tcp.

SaveTiming metrics

SaveTiming get reported to mw.performance.save in statsd. To see if it's running properly, the mw.performance.save.sample_rate key should have hits.

Synthetic metrics

The synthetic metrics are collected using VisualMetrics analyzing a video recording of the screen when the page is loading.

WebPageTest

The WebPageTest metrics are available in Graphite under the webpagetest prefix.

Visual Metrics

  • render: The time when something for the first time is painted within the viewport.
  • BackgroundImage: The time when the largest background image is painted at its final position within the viewport.
  • Heading: The time when the first h1/h2 heading is painted at its final position within the viewport.
  • LargestImage:The time when the largest image is painted at its final position within the viewport.
  • SpeedIndex:The Speed Index is the average time at which visible parts of the page are displayed. It is expressed in milliseconds and dependent on size of the view port.
  • lastVisualChange:The time when the last paint happens within the viewport.
  • VisualComplete85::The time when 85% of the content within the viewport is painted
  • VisualComplete95:The time when 95% of the content within the viewport is painted.
  • VisualComplete99:The time when 99% of the content within the viewport is painted.

Other timing metrics

  • fullyLoaded:The time all requests on the page has finished loading.
  • TTFB: The time to first byte delivered from the server.
  • domComplete: domComplete from the Navigation Timing APi.

Size and requests

WebPageTest also collects the number of bytes/request per type. Add .bytesor .requeststo the type to get that information.

  • html
  • css
  • js
  • flash
  • font
  • video
  • image
  • total: The total amount of bytes/requests for the tested page.

CPU times

These metrics are Chrome only.

  • Idle:Time spent being idle.
  • Layout:Time spent rendering the screen
  • Painting: Time spent in painting the screen.
  • Scripting:Time spent running JavaScript
  • Loading:Time spent in loading assets.

Visual Metrics

  • render: The time when something for the first time is painted within the viewport.
  • BackgroundImage: The time when the largest background image is painted at its final position within the viewport.
  • Heading: The time when the first h1/h2 heading is painted at its final position within the viewport.
  • LargestImage:The time when the largest image is painted at its final position within the viewport.
  • SpeedIndex:The Speed Index is the average time at which visible parts of the page are displayed. It is expressed in milliseconds and dependent on size of the view port.
  • lastVisualChange:The time when the last paint happens within the viewport.
  • VisualComplete85::The time when 85% of the content within the viewport is painted.
  • VisualComplete95:The time when 95% of the content within the viewport is painted.
  • VisualComplete99:The time when 99% of the content within the viewport is painted.

Other timing metrics

  • fullyLoaded:The time all requests on the page has finished loading.
  • TTFB: The time to first byte delivered from the server.
  • domComplete: domComplete from the Navigation Timing APi.

Size and requests

WebPageTest also collects the number of bytes/request per type. Add .bytes or .requests to the type to get that information.

  • html
  • css
  • js
  • flash
  • font
  • video
  • image
  • total: The total amount of bytes/requests for the tested page.

CPU times

These metrics are Chrome only.

  • Idle:Time spent being idle.
  • Layout:Time spent rendering the screen.
  • Painting: Time spent in painting the screen.
  • Scripting:Time spent running JavaScript.
  • Loading:Time spent in loading assets.

WebPageReplay

The WebPageReplay metrics are available in Graphite under the browsertime prefix (it's Browsertime that collect the metrics).

At the moment we collect Visual Metrics and CPU metrics (Chrome only).

Visual Metrics

  • FirstVisualChange:The time when something for the first time is painted within the viewport.
  • Heading: The time when the first h1 heading is painted at its final position within the viewport.
  • LargestImage: The time when the largest image is painted at its final position within the viewport.
  • Logo: The time when the logo is painted within the viewport.
  • CentralNotice: The time when the central notice banned is painted at its final position within the viewport.
  • VisualComplete85:The time when 85% of the content within the viewport is painted.
  • VisualComplete95:The time when 95% of the content within the viewport is painted.
  • VisualComplete99:The time when 99% of the content within the viewport is painted.
  • LastVisualChange:The time when the last paint happens within the viewport.
  • SpeedIndex: The Speed Index is the average time at which visible parts of the page are displayed. It is expressed in milliseconds and dependent on size of the view port.
  • PerceptualSpeedIndex: The Perceptual Speed Index is sensitive to page elements moving around (that is not Speed Index). For example if a campaign/banner pushes the elements, that will have bigger impact on the perceptual metric.

CPU metrics

  • Scripting: Time spent running JavaScript.
  • Painting: Time spent in painting the screen.
  • Rendering: Time spent rendering the screen.
  • Loading: Time spent in loading assets.

See also

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