max_vertices/max_primitives/local_size_x size tuning

[Try]

Hi, I have a question: what are good numbers for max_vertices / max_primitives, from you experience ?

niagara/src/shaders/meshlet.mesh.glsl

Lines 16 to 17 in e9f3a89

	layout(local_size_x = MESH_WGSIZE, local_size_y = 1, local_size_z = 1) in;
	layout(triangles, max_vertices = 64, max_primitives = 124) out;

Potentially with such layout driver will spawn ~64 helper threads, that wont do any real work: see slide 24
Also on stream, I've noticed that you are using Linux+AMD, so mesa guideline is probably very relevant to you machine.

On my side, after EXT came out, I've changed shader in my engine to local_size_x=max_primitives=max_vertices=64 - seems to work well on NV, and can't test on AMD unfortunately.

Can you test max_primitives=max_vertices=64 layout? Thanks!

[zeux]

As I mentioned on stream, we’re not using an efficient configuration right now. From my brief experiments 64/64 right now seems to be optimal on radv but it feels like some other options may be viable as well. We’ll explore that in a future stream.