radeonsi/gfx11: add a comment why we use PRIM_GRP_SIZE <= 252

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21041>
2023-01-23 23:40:36 -05:00
parent d21850f753
commit 0b4b309fc6
1 changed files with 1 additions and 0 deletions
@@ -1521,6 +1521,7 @@ static void gfx10_shader_ngg(struct si_screen *sscreen, struct si_shader *shader
      shader->ge_cntl = S_03096C_PRIMS_PER_SUBGRP(shader->ngg.max_gsprims) |
                        S_03096C_VERTS_PER_SUBGRP(shader->ngg.hw_max_esverts) |
                        S_03096C_BREAK_PRIMGRP_AT_EOI(break_wave_at_eoi) |
+                        /* This should be <= 252 for performance. 256 works too but is slower. */
                        S_03096C_PRIM_GRP_SIZE_GFX11(
                           CLAMP(252 / MAX2(shader->ngg.prim_amp_factor, 1),
                                 1, 256));