Telemetry: Add a Measurement

back to Telemetry Introduction

Are you sure you want to add a measurement?

Writing a good measurement is really hard.  We already have a bunch of measurements in tools/perf/perf_tools for you to use.  If you are looking to write a new benchmark, you probably just need to add or modify a page set and you might need to add new metrics to an existing measurement.  Think twice before you write another measurement.

What is a measurement?

A measurement is a python class that obtains a set of Numbers about a Page.  Measurements must work for all pages, not just one specific page.

For example, let’s say my users often go to a specific page, click a button, and scroll a div that shows up.  I could measure any number of things:

• How long it takes to go to that URL in a fresh tab until the div shows up

• How smoothly I can scroll a div

• How much time I spend in key WebKit systems: javascript, style, layout, paint, compositing

• How much the memory footprint varies as I scroll the div

• How much time I spend decoding images and painting the page

These are all examples of measurements.

I think I need to write a new measurement, now what?

Please email telemetry@chromium.org with details about what you are trying to measure.  We can help you get started and ensure that there are not existing measurements that you could use.