Raspberry Pi "V3D" OpenGL Driver Improving Performance With On-Disk Shader Cache

It's arguably long overdue, but landing today within Mesa 22.1 is support in the V3D driver for Mesa's on-disk shader cache functionality. By adding this shader cache to V3D it can help with the performance of this Gallium3D open-source driver most notably used by the Raspberry Pi 4 and newer single board computers.

Igalia has wired up the V3D on-disk shader cache support for caching compiled shaders to disk. This avoids recompiling shaders on subsequent loads for games and other applications. This can speed-up game load times and help in the performance in-game for those that load their shaders as needed.

This V3D shader cache work is sponsored by the Raspberry Pi Foundation and works across vertex / geometry / fragment / compute shaders. The V3DV Vulkan driver already had shader cache support.

As part of this V3D shader cache work, the V3D_DEBUG=cache environment variable is also added for helping to analyze the on-disk shader cache behavior.

More details on the Mesa GitLab for this long overdue V3D on-disk shader cache support.