At a glance

Adding a new performance test or modifying an existing test is much easier than most people think. In general, we need to create a patch for Talos by:

• determining if this is a startup or pageloader test
• creating the appropriate folder for your test in testing/talos/talos/tests
• adding all files and resources for the test (make sure there is no external network accesses) to that folder
• file a bug in the Testing::Talos component with your patch

Naming convention

t is pre-pended to the names to represent test

• ts = test startup
• tp = test pageload
• tdhtml = test dhtml

What we need to know about tests

When adding a new test, we really need to understand what we are doing. Here are some questions that you should know the answer to before adding a new test:

• What does this test measure?
• Does this test overlap with any existing test?
• What is the unit of measurement that we are recording?
• What would constitute a regression?
• What is the expected range in the results over time?
• Are there variables or conditions which would affect this test?
  • browser preferences, environment variables, etc?
  • operating system, system resources, time of day, etc...?
• Indepenedent of observation? Will this test produce the same number regardless of what was run before it?
• What considerations are there for how this test should be run and what tools are required?

Please document your new test along with answers to these questions in the Firefox Source Docs

Pageloader tests

A pageloader test is the most common. Using the pageloader extension allows for most of the reporting and talos integration to be done for you. Here is what you need to do:

• Create a new directory in testing/talos/talos/tests
• Create a manifest file named <testname>.manifest file in your directory (example)
  • Raw page load will just be a single URL line (example)
  • Internal measurements will have a % prior to the URL (example)
• Add your tests. For self reporting tests, use [tpRecordTime]
  • single page/value example
  • multiple pages/values example
• Add your test definition by adding a new class for your test to testing/talos/talos/test.py (example)
  • Add an item for tpmanifest, ${talos} is replaced with the current running directory (example)
  • Add an item for tpcycles (we recommend 1) and tppagecycles (we recommend 25 for a simple page, and 5 for a internal recording benchmark)
  • Add an item for filters (example)

Startup tests

A startup test is designed to load the browser with a single page many times. This is useful for tests which shouldn't have any extensions, can handle all loading and measuring themselves, or require the measurement of the browser startup. Here is what you need to do:

• Create a new directory in testing/talos/talos/startup_test
• Add your tests to the folder, these will be accessed by a raw URL
  • the tests need to report __start_report<value>__end_report so Talos can find it (example)
  • If you plan on doing shutdown times, you need to add in __startTimestamp<value>__endTimestamp. (example)
  • Include MozillaFileLogger.js and TalosPowersContent.js in your script (example)
• Add your test definition by adding a new class for your test to testing/talos/talos/test.py (example)
  • Add an item for cycles, we recommend 20
  • Add an item for url, this is relative to the Talos directory and what Firefox will load
  • Add tpmozafterpaint and set it to True by default, or False if your test does other internal measurements unrelated to rendering a page
  • Add an item for filters (example)

Adding a test to production

• File a bug to add tests to testing/talos/talos/test.py (see bug 893071 for an example).
• For mozilla-central on desktop only - just land your new test to your in-tree commit (on inbound/autoland) and ensure that you adjust testing/talos/talos.json to run the test
• If you add a new suite, edit taskcluster/ci/test/talos.yml to add the testname to a new suite, then add it to taskcluster/ci/test/test-sets.yml for all the different Talos test-sets.
• If this is an update to an existing test that could change the numbers, this needs to be treated as a new test and run side by side for a week to get a new baseline.
• Document the test in Firefox Source Docs