Servo Page Load Time Test

Prerequisites

• Python3

Basic Usage

./mach test-perf can be used to run a performance test on your servo build. The test result JSON will be saved to etc/ci/performance/output/. You can then run python test_differ.py to compare these two test results. Run python test_differ.py -h for instructions.

Setup for CI machine

CI for Servo

• Setup your Treeherder client ID and secret as environment variables TREEHERDER_CLIENT_ID and TREEHERDER_CLIENT_SECRET
• Run ./mach test-perf --submit to run and submit the result to Perfherder.

CI for Gecko

• Install Firefox Nightly in your PATH
• Download geckodriver and add it to the PATH (e.g. for Linux export PATH=$PATH:path/to/geckodriver)
• export FIREFOX_BIN=/path/to/firefox
• pip install selenium
• Run python gecko_driver.py to test
• Run test_all.sh --gecko --submit (omit --submit if you don't want to submit to perfherder)

How it works

• The testcase is from tp5, every testcase will run 20 times, and we take the median.
• Some of the tests will make Servo run forever, it's disabled right now. See https://github.com/servo/servo/issues/11087
• Each testcase is a subtest on Perfherder, and their summary time is the geometric mean of all the subtests.
• Notice that the test is different from the Talos TP5 test we run for Gecko. So you can NOT conclude that Servo is “faster” or “slower” than Gecko from this test.

Comparing the performance before and after a patch

• Run the test once before you apply a patch, and once after you apply it.
• python test_differ.py output/perf-<before time>.json output/perf-<after time>.json
• Green lines means loading time decreased, Blue lines means loading time increased.

Add your own test

• You can add two types of tests: sync test and async test
  • sync test: measure the page load time. Exits automatically after page loaded.
  • async test: measures your custom time markers from JavaScript, see page_load_test/example/example_async.html for example.
• Add you test case (html file) to the page_load_test/ folder. For example we can create a page_load_test/example/example.html
• Add a manifest (or modify existing ones) named page_load_test/example.manifest
• Add the lines like this to the manifest:

# Pages got served on a local server at localhost:8000
# Test case without any flag is a sync test
http://localhost:8000/page_load_test/example/example_sync.html
# Async test must start with a `async` flag
async http://localhost:8000/page_load_test/example/example.html

• Modify the MANIFEST=... link in test_all.sh and point that to the new manifest file.

Unit tests

You can run all unit tests (include 3rd-party libraries) with python -m pytest.

Individual test can be run by python -m pytest <filename>:

• test_runner.py
• test_submit_to_perfherder.py

Advanced Usage

Reducing variance

Running the same performance test results in a lot of variance, caused by the OS the test is running on. Experimentally, the things which seem to tame randomness the most are a) disbling CPU frequency changes, b) increasing the priority of the tests, c) running one one CPU core, d) loading files directly rather than via localhost http, and e) serving files from memory rather than from disk.

First run the performance tests normally (this downloads the test suite):

./mach test-perf

Disable CPU frequency changes, e.g. on Linux:

sudo cpupower frequency-set --min 3.5GHz --max 3.5GHz

Copy the test files to a tmpfs file, such as /run/user/, for example if your uid is 1000:

cp -r etc/ci/performance /run/user/1000

Then run the test suite on one core, at high priority, using a file:// base URL:

sudo nice --20 chrt -r 99 sudo -u *userid* taskset 1 ./mach test-perf --base file:///run/user/1000/performance/

These fixes seem to take down the variance for most tests to under 5% for individual tests, and under 0.5% total.

(IRC logs: 2017-11-09 | 2017-11-10 )

Test Perfherder Locally

If you want to test the data submission code in submit_to_perfherder.py without getting a credential for the production server, you can setup a local treeherder VM. If you don't need to test submit_to_perfherder.py, you can skip this step.

• Add 192.168.33.10 local.treeherder.mozilla.org to /etc/hosts
• git clone https://github.com/mozilla/treeherder; cd treeherder
• vagrant up
• vagrant ssh
  • ./bin/run_gunicorn
• Outside of vm, open http://local.treeherder.mozilla.org and login to create an account
• vagrant ssh
  • ./manage.py create_credentials <username> <email> "description", the email has to match your logged in user. Remember to log-in through the Web UI once before you run this.
  • Setup your Treeherder client ID and secret as environment variables TREEHERDER_CLIENT_ID and TREEHERDER_CLIENT_SECRET