lightswitch

lightswitch is a profiler as a library for Linux suitable for on-demand and continuous profiling. While lightswitch is a Rust application, the unwinders are written in C and run in BPF. Currently C, C++, Rust, and Zig are fully supported on x86_64.

Usage

As a CLI, lightswitch can be run with:

$ sudo lightswitch

It can be stopped with Ctrl+C, or alternatively, by passing a --duration in seconds. A flamegraph in SVG will be written to disk. Pprof is also supported with --profile-format=pprof. By default the whole machine will be profiled, to profile invidual processes you can use --pids.

Container images in the OCI format (Docker compatible) can be downloaded from the published packages. As of now, new container images are published on merges to the main branch

Using Docker:

$ docker run -it --privileged --pid=host -v /sys:/sys -v $PWD:/profiles -v /tmp/lightswitch ghcr.io/javierhonduco/lightswitch:main-$LIGHTSWITCH_SHA1 --profile-path=/profiles

Development

We use nix for the development environment and the building system. It can be installed with the official installer (make sure to enable support for flakes) or with the Determinate Systems installer. Once nix is installed, you can

• start a developer environment with nix develop and then you'll be able to build the project with cargo with cargo build. This might take a little while the first time.
• generate a container image nix build .#container will write a symlink to the container image under ./result.

Building

# after running `nix develop`
$ cargo build # use `--release` to get an optimized build
$ sudo ./target/debug/lightswitch # or ./target/release for optimized builds

Running tests

# after running `nix develop`
$ cargo test

Running kernel tests

$ nix run .#vmtest

Project status

lightswitch is in active development and the main focus is to provide a low-overhead profiler with excellent UX. A more comprehensive roadmap will be published. Feedback is greatly appreciated.