Performance

This is the entrypoint for documentation and infrastructure developed or operated by the Performance Team at Wikimedia.

For more information about the team, what we do, and how to reach us, see Wikimedia Performance Team on mediawiki.org.

Guides

The "performance practices" guides help set direction, and can be used to guide new developments, or to periodically identify areas of improvement in current code by looking for differences.

The "measure" guides help assess the actual performance of existing code, and to help iterate on proposed changes before, during, and after their development.

Tools and data

Tools we provide for use by engineers that develop or operate Wikimedia software.

Frontend synthetic traffic

Page drilldown (Grafana): Detailed performance measures from synthetic testing of page views and user journeys (split by URL, connection type, browser, and more). The same dashboard and feature-set covers Synthetic testing both from desktop browsers and our Mobile Device Lab.
ResourceLoader bundle size (Grafana): Stats about the size of your asset bundles.
ResourceLoader module builds (Grafana): Stats about how long your asset bundles take to build during cache misses.
ResourceLoader manifest size (Grafana): The size of your module metadata (name, dependencies, version hash) as sent to the browser in the site-wide "startup" request from all pageviews.

Frontend real-user traffic

Navigation Timing (Grafana): Page load time and other real-user metrics from MediaWiki page views, collected via Navigation Timing and Paint Timing APIs (split by platform, country, and browser).

responseStart by CDN host (Grafana): Roundtrip latency from browsers, split by CDN host. Allows for natural experimentation and regression detection around Wikimedia CDN, e.g. Linux kernel changes, and upgrades or configuration changes to Varnish, HAProxy or ATS.
CruX report (Grafana): Independent copy of Google's periodically published Chrome UX Report and the Core Web Vitals as measured from eligible Chrome-with-Google-account users.
CPU benchmark (Grafana): Collected as part of our Navigation Timing beacon to help asses baseline performance. Also powers the AS Report.
Google Web Vitals (Grafana): Google Web Vitals metrics important for a good user experience, collected by us.
AS Report (performance.wikimedia.org): Periodic comparison of backbone connectivity from different Internet service providers, based on anonymised Navigation Timing and CPU benchmark datasets.

Analyze backend traffic

Backend Pageview Timing: Overall backend latency from MediaWiki when generating pageviews, e.g. to the CDN and to logged-in users.
Backend Save Timing (Grafana): Overall latency when saving edits to articles. See also Save Timing breakdown by page type, account type, and entry point.
MediaWiki Entrypoint Profiling (Grafana): Breakdown backend latency of any request route, by attributing time spent to high-level components in core and extensions.
WANCache (Grafana): Performance stats for specific chunks of MediaWiki code in core and extensions.
PHP Flame Graphs (performance.wikimedia.org): Breakdown MediaWiki backend latency to individual function calls from sampled stacktraces (reported hourly and daily, split by service entry point).

Debugging and development

mw.inspect: Inspect frontend build sizes in production or locally during development.
Fresnel CI: Easy access to frontend performance stats during code review (a selection of synthetic and real-user metrics).
WikimediaDebug: Capture per-request data when debugging in production, e.g. ad-hoc, when staging a deployment.
- Excimer UI: Flame graphs to visualise time spent through detailed stack traces from function calls.
- Verbose logs: Capture verbose debug messages in Logstash.
- XHGui: Analyze server performance through memory use and function call count.

Misc

noc.wikimedia.org/db.php: Database load config.
noc.wikimedia.org/wiki.php: MediaWiki site settings.

Essays

Internal runbooks

These pages are mainly for use within the team.

Internal workflows:

logstash.wikimedia.org (NDA restricted).

Gerrit: Performance Team dashboard (how-to: Add Gerrit navigation link)

Grafana dashboards that monitor internal services:

Contact

Phabricator issue tracker: #Performance-Team (triaged within 7 days)
Libera Chat IRC: #wikimedia-perf ^connect
Email: performance-team@wikimedia.org
or reach out directly to Larissa Gaulia.