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anv: Disable the vertex cache when tessellating on SKL GT4 

I have no idea if I'm correct about what's going wrong or if this is the
correct fix.  However, in my multiple weeks of banging my head on this
hang, a VUE reference counting bug seems to match all the symptoms and
it definitely fixes the hang.

Cc: mesa-stable@lists.freedesktop.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107280
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Jason Ekstrand 2018-08-21 20:40:50 -05:00
parent 5dee89438a
commit b08b4b2b25
1 changed files with 22 additions and 1 deletions
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23
src/intel/vulkan/genX_pipeline.c
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@ -1173,7 +1173,28 @@ emit_3dstate_vs(struct anv_pipeline *pipeline)
vs.IllegalOpcodeExceptionEnable = false;
vs.SoftwareExceptionEnable = false;
vs.MaximumNumberofThreads = devinfo->max_vs_threads - 1;
vs.VertexCacheDisable = false;
if (GEN_GEN == 9 && devinfo->gt == 4 &&
anv_pipeline_has_stage(pipeline, MESA_SHADER_TESS_EVAL)) {
/* On Sky Lake GT4, we have experienced some hangs related to the VS
* cache and tessellation. It is unknown exactly what is happening
* but the Haswell docs for the "VS Reference Count Full Force Miss
* Enable" field of the "Thread Mode" register refer to a HSW bug in
* which the VUE handle reference count would overflow resulting in
* internal reference counting bugs. My (Jason's) best guess is that
* this bug cropped back up on SKL GT4 when we suddenly had more
* threads in play than any previous gen9 hardware.
*
* What we do know for sure is that setting this bit when
* tessellation shaders are in use fixes a GPU hang in Batman: Arkham
* City when playing with DXVK (https://bugs.freedesktop.org/107280).
* Disabling the vertex cache with tessellation shaders should only
* have a minor performance impact as the tessellation shaders are
* likely generating and processing far more geometry than the vertex
* stage.
*/
vs.VertexCacheDisable = true;
}
vs.VertexURBEntryReadLength = vs_prog_data->base.urb_read_length;
vs.VertexURBEntryReadOffset = 0;