Firefox OS/Performance/Profiling

Profiling with the gecko profiler

Good at: Native stacks (with runtime options) + javascript profiling, low overhead sampling, familiar for gecko developers

See these instructions. Patches are in-flight to get native stacks in profiles, but that's not in default configurations yet.

Profiling with systrace

Good at: Shows process preemption, shows all calls to instrumented functions, Familiar for android developers

Bad at: Requires configure option, higher overhead

Better instructions coming: Build with '--enable-systrace' and follow these instructions for systrace.py.

Note: If you're profiling on device with Android 4.3 and sometimes you can only see B2G process in your profile data, please reboot your device and try to profile again. By the way, gecko code is tagged as 'gfx', so the command is for your reference.

./systrace.py --time=10 -o mynewtrace.html sched gfx