[Mesa-dev] [PATCH 3/3] radv: set FORCE_SIMD_DIST(1) for compute when profitable

[Bas Nieuwenhuizen]

Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

Would it make sense to move the compute_resource_limits calculation to
pipeline creation time?

On Thu, Dec 14, 2017 at 3:51 PM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> Ported from RadeonSI.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/amd/vulkan/radv_cmd_buffer.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
> index d6aaff707b..4a048485c8 100644
> --- a/src/amd/vulkan/radv_cmd_buffer.c
> +++ b/src/amd/vulkan/radv_cmd_buffer.c
> @@ -2561,6 +2561,7 @@ radv_emit_compute_pipeline(struct radv_cmd_buffer *cmd_buffer)
>  {
>         struct radv_shader_variant *compute_shader;
>         struct radv_pipeline *pipeline = cmd_buffer->state.compute_pipeline;
> +       struct radv_device *device = cmd_buffer->device;
>         unsigned compute_resource_limits;
>         unsigned waves_per_threadgroup;
>         uint64_t va;
> @@ -2602,6 +2603,19 @@ radv_emit_compute_pipeline(struct radv_cmd_buffer *cmd_buffer)
>         compute_resource_limits =
>                 S_00B854_SIMD_DEST_CNTL(waves_per_threadgroup % 4 == 0);
>
> +       if (device->physical_device->rad_info.chip_class >= CIK) {
> +               unsigned num_cu_per_se =
> +                       device->physical_device->rad_info.num_good_compute_units /
> +                       device->physical_device->rad_info.max_se;
> +
> +               /* Force even distribution on all SIMDs in CU if the workgroup
> +                * size is 64. This has shown some good improvements if # of
> +                * CUs per SE is not a multiple of 4.
> +                */
> +               if (num_cu_per_se % 4 && waves_per_threadgroup == 1)
> +                       compute_resource_limits |= S_00B854_FORCE_SIMD_DIST(1);
> +       }
> +
>         radeon_set_sh_reg(cmd_buffer->cs, R_00B854_COMPUTE_RESOURCE_LIMITS,
>                           compute_resource_limits);
>
> --
> 2.15.1
>
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