Performance/Metrics

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.

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.

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.

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.

• View Grafana dashboard
• View Coal dashboard

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-synthetic-testing under the sitespeed_io prefix (it's Browsertime/sitespeed.io that collect the metrics).

At the moment we all the default metrics that is collected when you sitespeed.io. Here's a list of some of the most important ones:

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.
• 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

• LongTasks.tasks : the number CPU long tasks (> 50 ms)
• LongTasks.beforeFirstPaint : the number CPU long tasks happening before anything is painted on the screen (> 50 ms)
• LongTasks.totalDuration : the total time (in ms) spent in CPU long tasks
• LongTasks.beforeFirstPaint.totalDuration : the total time (in ms) spent in CPU long tasks before anything was painted on the screen.

See also

• Performance
• performance.wikimedia.org