Mesa 22.3 Tunes Intel Arc Graphics For Better Vulkan Mesh Shading Performance

Merged this morning into Mesa 22.3 are some adjustments to Intel's open-source "ANV" Vulkan driver for delivering better Vulkan mesh shading performance with Arc Graphics hardware.

Back in September Intel's Vulkan Linux driver added mesh shader support following the introduction of VK_EXT_mesh_shader in Vulkan 1.3.226 for finally providing a cross-vendor mesh shading extension for this graphics API. That code given the timing is only now approaching stable with Mesa 22.3 while being squeezed in today are some important performance optimizations for Intel's latest graphics processors with this capability.

Tweaking some task/mesh distribution batch size values to match Intel's internal hardware recommendations has been confirmed to help with some Vulkan meshlet scenes running on an Arc Graphics A770.

Meanwhile, adjusting the maximum number of thread groups value can provide measurable benefit:

Documentation is worded in a confusing way, which may be understood that we don't have to set this field to get good results.

MESH part of this commit improves performance of vk_meshlet_cadscene by a factor of 2 on A380.

There is also another patch for correcting the maximum number of thread groups.

These three patches to better tune the Intel ANV mesh shading performance for Arc Graphics are now merged for Mesa 22.3. The v22.3 feature freeze / branching is set to happen in the coming days and then the release candidate period for a few weeks followed by the Mesa 22.3 stable debut. Mesa 22.3 is highly recommended for Arc Graphics dGPUs over the preliminary support found in Mesa 22.2.