GLXOSD is an on-screen display (OSD)/overlay for OpenGL applications running on Linux with X11. It can show FPS, the temperature of your CPU, and if you have an NVIDIA graphics card (with proprietary drivers), it will also show the temperature of the GPU. Also, it can log frame timings, which is useful for benchmarking. This project aims to provide some of the functionality that RivaTuner OSD (which is used by MSI Afterburner) provides under Windows.
This is a companion discussion topic for the original entry at https://copr.fedorainfracloud.org/coprs/kparal/glxosd/