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: Gecko code is tagged as ATRACE_TAG_ALWAYS, so the command is for your reference.

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