[Mesa-dev] [PATCH v2 1/2] anv/cmd_buffer: Don't temporarily enable CCS_E within a render pass

[Jason Ekstrand]

Perf numbers in the commit message would be nice

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

On Thu, Feb 2, 2017 at 8:15 AM, Nanley Chery <nanleychery at gmail.com> wrote:

> Compressing a render target and decompressing it in the same
> single-subpass render pass may waste bandwidth. While this may be
> beneficial in some circumstances, it does not help in all.
>
> v2 (Jason Ekstrand):
> - Provide a more thorough comment
> - Enable CCS_D for input attachments
>
> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> ---
>  src/intel/vulkan/genX_cmd_buffer.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/src/intel/vulkan/genX_cmd_buffer.c
> b/src/intel/vulkan/genX_cmd_buffer.c
> index 63911f2c8e..cba876b58e 100644
> --- a/src/intel/vulkan/genX_cmd_buffer.c
> +++ b/src/intel/vulkan/genX_cmd_buffer.c
> @@ -266,13 +266,24 @@ color_attachment_compute_aux_usage(struct
> anv_device *device,
>        att_state->fast_clear = false;
>     }
>
> -   if (isl_format_supports_lossless_compression(&device->info,
> -                                                iview->isl.format)) {
> +   /**
> +    * TODO: Consider using a heuristic to determine if temporarily
> enabling
> +    * CCS_E for this image view would be beneficial.
> +    *
> +    * While fast-clear resolves and partial resolves are fairly cheap in
> the
> +    * case where you render to most of the pixels, full resolves are not
> +    * because they potentially involve reading and writing the entire
> +    * framebuffer.  If we can't texture with CCS_E, we should leave it
> off and
> +    * limit ourselves to fast clears.
> +    */
> +   if (iview->image->aux_usage == ISL_AUX_USAGE_CCS_E) {
>        att_state->aux_usage = ISL_AUX_USAGE_CCS_E;
>        att_state->input_aux_usage = ISL_AUX_USAGE_CCS_E;
>     } else if (att_state->fast_clear) {
>        att_state->aux_usage = ISL_AUX_USAGE_CCS_D;
> -      if (GEN_GEN >= 9) {
> +      if (GEN_GEN >= 9 &&
> +          !isl_format_supports_lossless_compression(&device->info,
> +                                                    iview->isl.format)) {
>           /* From the Sky Lake PRM, RENDER_SURFACE_STATE::
> AuxiliarySurfaceMode:
>            *
>            *    "If Number of Multisamples is MULTISAMPLECOUNT_1, AUX_CCS_D
> --
> 2.11.0
>
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>
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