fxprof-perf-convert

A converter from the Linux perf perf.data format into the Firefox Profiler format, specifically into the processed profile format.

Here's an example profile of Firefox. And here's a profile of the conversion process of that example. Both of these profiles were obtained by running perf record --call-graph dwarf and then converting the perf.data file.

Run

For best results, run perf record as root and use the following arguments to capture context switch events and off-cpu stacks:

$ sudo perf record -e cycles -e sched:sched_switch --switch-events --sample-cpu -m 8M --aio --call-graph dwarf,32768 --pid <pid>
$ sudo chown $USER perf.data

Then run the converter:

$ cargo run --release -- perf.data

This creates a file called profile-conv.json.

Then open the profile in the Firefox profiler:

$ profiler-symbol-server profile-conv.json   # Install with `cargo install profiler-symbol-server`

That's it.

More command lines

If you don't want to attach to an existing process, and instead want to launch a new process, you can use something like this:

$ sudo perf record -e cycles -e sched:sched_switch --switch-events --sample-cpu -m 8M --aio --call-graph dwarf,32768 sudo -u $USER env "PATH=$PATH" sh -c 'YOUR COMMAND' && sudo chown $USER perf.data

It's not the best. If you know of a better way to make perf run as root and invoke a program as non-root, please let me know. Thanks!