IssueTracker

Note that androidx.benchmark.ProfilerTest#methodSamplingSimpleperf has been 100% failing in CI https://android-build.googleplex.com/builds/tests/view?invocationId=I87700005330476092&testResultId=TR24710817326417073

java.lang.Error: linux perf events aren't enabled on the device. Please run api_profiler.py.
	at androidx.benchmark.simpleperf.ProfileSession.checkIfPerfEnabled(ProfileSession.java:296)
	at androidx.benchmark.simpleperf.ProfileSession.startRecording(ProfileSession.java:142)
	at androidx.benchmark.simpleperf.ProfileSession.startRecording(ProfileSession.java:125)
	at androidx.benchmark.MethodSamplingSimpleperf.start(Profiler.kt:174)
	at androidx.benchmark.ProfilerTest.verifyProfiler(ProfilerTest.kt:56)
	at androidx.benchmark.ProfilerTest.methodSamplingSimpleperf(ProfilerTest.kt:80)
	at java.lang.reflect.Method.invoke(Native Method)

With the patch in #5, simpleperf is supported, but it's cumbersome, and doesn't support outputting a file that Studio can read. A few things remain to make this easier to use, so we can ship externally:

1) Create Studio .trace file

Simpleperf docs explain how to convert the output <name>.data file output by simpeperf on device to a .trace file Studio can open. See Simpleperf docs on creating .trace file. That simpleperf executable is currently used by ProfileSession.java, so this would just be extra functionality there.

Currently, the trace file is output to /data/data/<package>/simpleperf_data/***.data. We can leave that file there for now, so that it can be copied by simpleperf/scripts/api_profiler.py collect, but we should put a copy of it in additionalTestOutputDir/.

2) Replicate api_profiler.py prepare functionality

See http://go/androidx-bench-dev#initial-setup, specifically api_profiler.py Looks like it just runs a bunch of ADB setprop commands, so should be fairly straightforward. It does also copy an updated version of simpleperf onto the device, but since running that version isn't supported on user builds (it has to be build into system image), we'll skip that part.

3) Switch MethodTracing to use simpleperf by default on supported devices

Once the above 2 are resolved, rename MethodTracing -> MethodTracingLegacy, and MethodTracingSimpleperf -> MethodTracing.

Use simpleperf by default on API 28+, but let people opt into the old version by passing "MethodTracingLegacy".

@Aurimas - that failure is because this functionality requires running a host-side script before it will work, but fixing 2) above will fix that.

I marked the test @FlakyTest, but if there's a better way to make it not run at all in pre/postsubmit, happy to make that change.

Landed documentation updates with cl/406002135. Marking this as fixed, and filed b/204370903 for making opening the trace files easier by linking in Studio.