usdt

Introduction

usdt is a Go package for linking cilium/ebpf's Program to userspace statically defined tracepoints.

Getting started

You can find an example in the examples folder.

To try it, start a python process:

(venv) ➜  cpython git:(main) ✗ python
Python 3.10.4 (main, Mar 25 2022, 00:00:00) [GCC 11.2.1 20220127 (Red Hat 11.2.1-9)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.getpid()
373829

Then run the Go process and observe function__entry tracepoint events:

go run -exec sudo ./ -pid 373829

/usr/lib64/python3.10/random.py:366 -> randint()
/usr/lib64/python3.10/random.py:292 -> randrange()
/usr/lib64/python3.10/random.py:239 -> _randbelow_with_getrandbits()

Testing

Install dev dependencies

• clang 12
• apt install systemtap-sdt-dev (Debian/Ubuntu), dnf install systemtap-sdt-devel (Fedora)
• pip install stapsdt black isort
• https://github.com/linux-usdt/libstapsdt

make -C testdata
go test -exec sudo -v ./

More links and documentation

• https://lwn.net/Articles/753601/
• https://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
• https://bpf.sh/usdt-report-doc/index.html
• https://bpf.sh/production-breakpoints-doc/index.html
• https://medium.com/sthima-insights/we-just-got-a-new-super-power-runtime-usdt-comes-to-linux-814dc47e909f
• https://github.com/goldshtn/linux-tracing-workshop/blob/master/bpf-usdt.md

License

The code and docs are released under the MIT.