Perf Try Bots

Chrome has a performance lab with dozens of device and OS configurations. Pinpoint is the service that lets you run performance tests in the lab. With Pinpoint, you can run try jobs, which let you put in a Gerrit patch, and it will run tip-of-tree with and without the patch applied.

Why perf try jobs?

• All of the devices exactly match the hardware and OS versions in the perf continuous integration suite.
• The devices have the “maintenance mutex” enabled, reducing noise from background processes.
• Some regressions take multiple repeats to reproduce, and Pinpoint automatically runs multiple times and aggregates the results.
• Some regressions reproduce on some devices but not others, and Pinpoint will run the job on multiple devices.

Starting a perf try job

• Visit Pinpoint.
• Check the upper-right corner of the page. If you see a “Sign in” link, click it and sign in with an account that has trybot access. (If the link shows “Sign out”, then you are already signed in.)
• Click the perf try button in the bottom right corner of the screen.

You should see the following dialog popup:

Benchmark Configuration	Description
Bot	The device type to run the test on. All hardware configurations in our perf lab are supported.
Benchmark	A telemetry benchmark. E.g. system_health.common_desktop All the telemetry benchmarks are supported by the perf trybots. To get a full list, run tools/perf/run_benchmark list To learn more about the benchmarks, you can read about the system health benchmarks, which test Chrome's performance at a high level, and the benchmark harnesses, which cover more specific areas.
Story	(optional) A specific story from the benchmark to run. Note that if the story you want isn‘t on the dropdown it could be because the story is new and so the Chromeperf dashboard database doesn’t know about it yet. In that case you can still free-form type the exact story name into the field.
Story Tags	(optional) A list of story tags. All stories in the given benchmark that match any of the tags will be run.
Extra Test Arguments	(optional) Extra arguments for the test. E.g. --extra-chrome-categories="foo,bar" To see all arguments, run tools/perf/run_benchmark run --help

Note that you must provide either a Story or a Story Tag for Pinpoint to run. Per this explanation, running an entire benchmark on Pinpoint can cause significant problems if the benchmark is large. For this reason, some small benchmarks have an ‘all’ tag available that applies to all the stories in the benchmark, so please use that tag to run all the stories for a small benchmark. Please see this bug for details on work to add the ‘all’ tag to more benchmarks. If you want to run a large benchmark, consider choosing one of the tags that benchmark provides to select a subset of the available stories for that benchmark.

Job Configuration	Description
Base Git Hash	The Git Hash that you want to put your Gerrit patch on top of.
Gerrit URL	The patch you want to run the benchmark on. Patches in dependent repos (e.g. v8, skia) are supported. Pinpoint will also post updates on the Gerrit comment list.
Bug ID	(optional) A bug ID. Pinpoint will post updates on the bug.

Interpreting the results

Detailed results

On the Job result page, click the “Analyze benchmark results” link at the top. See the metrics results UI documentation for more details on reading the results.

Traces

On the Job result page, there is a chart containing two dots. The left dot represents HEAD and the right dot represents the patch. Clicking on the right dot reveals some colored bars; each box represents one benchmark run. Click on one of the runs to see trace links.