Add -fno-omit-frame-pointer and -mno-omit-leaf-frame-pointer to default compilation flags

[artizirk]

Since Python 3.12 it is possible to profile Python programs using Linux perf profiler when setting PYTHONPERFSUPPORT=1 environment variable. Unfortunately currently built Python containers are missing fno-omit-frame-pointer -mno-omit-leaf-frame-pointer CFLAGS which result in quite useless perf stack traces. It would be great to have those extra CFLAGS added to the image build. That would allow everyone to do low overhead performance profiling on production systems.

• https://docs.python.org/3.12/howto/perf_profiling.html
• https://ubuntu.com/blog/ubuntu-performance-engineering-with-frame-pointers-by-default
• https://fedoraproject.org/wiki/Changes/fno-omit-frame-pointer
• https://www.brendangregg.com/blog/2024-03-17/the-return-of-the-frame-pointers.html

[tianon]

Sorry, I'm not sure how I missed this 😭

Are there downsides to changing these by default? Presumably these are omitted by default in the compiler intentionally, and I'd like to make sure we understand why before we disable them (that upstream Python page is great, but the way I read it is "if you want perf, you should build this way" not necessarily "it's generally a good idea to build all Python binaries this way" which is a slightly different thing).

After typing that, I read your other links (thank you!!) and both Ubuntu and Fedora doing this by default for the whole distro is a pretty strong signal for me. 😄