On 07.06.2017 13:36, Nicolai Hähnle wrote:
On 06.06.2017 16:30, Marek Olšák wrote:
From: Marek Olšák <marek.ol...@amd.com>

The workaround causes a massive performance decrease on 1-SE parts.
(Cape Verde, Hainan, Oland)

The performance regression is already part of 17.0 and 17.1.

Cc: 17.0 17.1 <mesa-sta...@lists.freedesktop.org>
---
  src/gallium/drivers/radeonsi/si_state_draw.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/drivers/radeonsi/si_state_draw.c b/src/gallium/drivers/radeonsi/si_state_draw.c
index cd069e3..75e83ff 100644
--- a/src/gallium/drivers/radeonsi/si_state_draw.c
+++ b/src/gallium/drivers/radeonsi/si_state_draw.c
@@ -188,21 +188,21 @@ static void si_emit_derived_tess_state(struct si_context *sctx,
       */
      *num_patches = MIN2(*num_patches, 40);
      if (sctx->b.chip_class == SI) {
          /* SI bug workaround, related to power management. Limit LS-HS
           * threadgroups to only one wave.
           */
unsigned one_wave = 64 / MAX2(num_tcs_input_cp, num_tcs_output_cp);
          *num_patches = MIN2(*num_patches, one_wave);
-        if (sctx->screen->b.info.max_se == 1) {
+        if (sctx->screen->b.info.max_se == 1 && tcs->info.uses_primid) {

This is insufficient. All downstream shader stages are affected, including TES, GS, and even PS (unless there's an API GS -- in that case, the PS gets the GS primid output).

Basically, I think this should use sctx->ia_multi_vgt_param_key.u.tess_uses_prim_id.

Then there's still the issue that state changes need to be taken into account.



Cheers,
Nicolai


              /* The VGT HS block increments the patch ID unconditionally
               * within a single threadgroup. This results in incorrect
               * patch IDs when instanced draws are used.
               *
               * The intended solution is to restrict threadgroups to
               * a single instance by setting SWITCH_ON_EOI, which
               * should cause IA to split instances up. However, this
               * doesn't work correctly on SI when there is no other
               * SE to switch to.
               */





--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
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