[Mesa-dev] [PATCH 1/5] anv: Move push constant allocation to the command buffer
Jordan Justen
jordan.l.justen at intel.com
Fri May 27 20:01:42 UTC 2016
On 2016-05-20 12:41:04, Jason Ekstrand wrote:
> Instead of blasting it out as part of the pipeline, we put it in the
> command buffer and only blast it out when it's really needed. Since the
> PUSH_CONSTANT_ALLOC commands aren't pipelined, they immediately cause a
> stall which we would like to avoid.
> ---
> src/intel/vulkan/anv_cmd_buffer.c | 1 +
> src/intel/vulkan/anv_pipeline.c | 22 ----------
> src/intel/vulkan/anv_private.h | 2 +-
> src/intel/vulkan/genX_cmd_buffer.c | 78 +++++++++++++++++++++++++++++++----
> src/intel/vulkan/genX_pipeline_util.h | 12 ------
> 5 files changed, 71 insertions(+), 44 deletions(-)
>
> diff --git a/src/intel/vulkan/anv_cmd_buffer.c b/src/intel/vulkan/anv_cmd_buffer.c
> index bba24e8..db7793e 100644
> --- a/src/intel/vulkan/anv_cmd_buffer.c
> +++ b/src/intel/vulkan/anv_cmd_buffer.c
> @@ -130,6 +130,7 @@ anv_cmd_state_reset(struct anv_cmd_buffer *cmd_buffer)
> state->descriptors_dirty = 0;
> state->push_constants_dirty = 0;
> state->pipeline = NULL;
> + state->push_constant_stages = 0;
> state->restart_index = UINT32_MAX;
> state->dynamic = default_dynamic_state;
> state->need_query_wa = true;
> diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
> index faa0adb..c010f0f 100644
> --- a/src/intel/vulkan/anv_pipeline.c
> +++ b/src/intel/vulkan/anv_pipeline.c
> @@ -939,28 +939,6 @@ anv_compute_urb_partition(struct anv_pipeline *pipeline)
> pipeline->urb.start[MESA_SHADER_TESS_EVAL] = push_constant_chunks;
> pipeline->urb.size[MESA_SHADER_TESS_EVAL] = 1;
> pipeline->urb.entries[MESA_SHADER_TESS_EVAL] = 0;
> -
> - const unsigned stages =
> - _mesa_bitcount(pipeline->active_stages & VK_SHADER_STAGE_ALL_GRAPHICS);
> - unsigned size_per_stage = stages ? (push_constant_kb / stages) : 0;
> - unsigned used_kb = 0;
> -
> - /* Broadwell+ and Haswell gt3 require that the push constant sizes be in
> - * units of 2KB. Incidentally, these are the same platforms that have
> - * 32KB worth of push constant space.
> - */
> - if (push_constant_kb == 32)
> - size_per_stage &= ~1u;
> -
> - for (int i = MESA_SHADER_VERTEX; i < MESA_SHADER_FRAGMENT; i++) {
> - pipeline->urb.push_size[i] =
> - (pipeline->active_stages & (1 << i)) ? size_per_stage : 0;
> - used_kb += pipeline->urb.push_size[i];
> - assert(used_kb <= push_constant_kb);
> - }
> -
> - pipeline->urb.push_size[MESA_SHADER_FRAGMENT] =
> - push_constant_kb - used_kb;
> }
>
> static void
> diff --git a/src/intel/vulkan/anv_private.h b/src/intel/vulkan/anv_private.h
> index 33cbff9..80e768d 100644
> --- a/src/intel/vulkan/anv_private.h
> +++ b/src/intel/vulkan/anv_private.h
> @@ -1177,6 +1177,7 @@ struct anv_cmd_state {
> uint32_t restart_index;
> struct anv_vertex_binding vertex_bindings[MAX_VBS];
> struct anv_descriptor_set * descriptors[MAX_SETS];
> + VkShaderStageFlags push_constant_stages;
> struct anv_push_constants * push_constants[MESA_SHADER_STAGES];
> struct anv_state binding_tables[MESA_SHADER_STAGES];
> struct anv_state samplers[MESA_SHADER_STAGES];
> @@ -1411,7 +1412,6 @@ struct anv_pipeline {
> uint32_t scratch_start[MESA_SHADER_STAGES];
> uint32_t total_scratch;
> struct {
> - uint8_t push_size[MESA_SHADER_FRAGMENT + 1];
> uint32_t start[MESA_SHADER_GEOMETRY + 1];
> uint32_t size[MESA_SHADER_GEOMETRY + 1];
> uint32_t entries[MESA_SHADER_GEOMETRY + 1];
> diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
> index ee47c29..f5e3530 100644
> --- a/src/intel/vulkan/genX_cmd_buffer.c
> +++ b/src/intel/vulkan/genX_cmd_buffer.c
> @@ -274,6 +274,72 @@ void genX(CmdPipelineBarrier)(
> }
> }
>
> +static void
> +cmd_buffer_alloc_push_constants(struct anv_cmd_buffer *cmd_buffer)
> +{
> + VkShaderStageFlags stages = cmd_buffer->state.pipeline->active_stages;
> +
> + /* In order to avoid thrash, we assume that vertex and fragment stages
> + * always exist. In the rare case where one is missing *and* the other
> + * uses push concstants, this may be suboptimal. However, avoiding stalls
> + * seems more important.
> + */
> + stages |= VK_SHADER_STAGE_FRAGMENT_BIT | VK_SHADER_STAGE_VERTEX_BIT;
> +
> + if (stages == cmd_buffer->state.push_constant_stages)
> + return;
> +
> +#if GEN_GEN >= 8
> + const unsigned push_constant_kb = 32;
> +#elif GEN_IS_HASWELL
> + const unsigned push_constant_kb = cmd_buffer->device->info.gt == 3 ? 32 : 16;
> +#else
> + const unsigned push_constant_kb = 16;
> +#endif
I noted that this changed from the old code that just used 32k. I see
that this matches src/mesa/drivers/dri/i965/gen7_urb.c. Maybe worth
noting in the commit message?
Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>
> +
> + const unsigned num_stages =
> + _mesa_bitcount(stages & VK_SHADER_STAGE_ALL_GRAPHICS);
> + unsigned size_per_stage = push_constant_kb / num_stages;
> +
> + /* Broadwell+ and Haswell gt3 require that the push constant sizes be in
> + * units of 2KB. Incidentally, these are the same platforms that have
> + * 32KB worth of push constant space.
> + */
> + if (push_constant_kb == 32)
> + size_per_stage &= ~1u;
> +
> + uint32_t kb_used = 0;
> + for (int i = MESA_SHADER_VERTEX; i < MESA_SHADER_FRAGMENT; i++) {
> + unsigned push_size = (stages & (1 << i)) ? size_per_stage : 0;
> + anv_batch_emit(&cmd_buffer->batch,
> + GENX(3DSTATE_PUSH_CONSTANT_ALLOC_VS), alloc) {
> + alloc._3DCommandSubOpcode = 18 + i;
> + alloc.ConstantBufferOffset = (push_size > 0) ? kb_used : 0;
> + alloc.ConstantBufferSize = push_size;
> + }
> + kb_used += push_size;
> + }
> +
> + anv_batch_emit(&cmd_buffer->batch,
> + GENX(3DSTATE_PUSH_CONSTANT_ALLOC_PS), alloc) {
> + alloc.ConstantBufferOffset = kb_used;
> + alloc.ConstantBufferSize = push_constant_kb - kb_used;
> + }
> +
> + cmd_buffer->state.push_constant_stages = stages;
> +
> + /* From the BDW PRM for 3DSTATE_PUSH_CONSTANT_ALLOC_VS:
> + *
> + * "The 3DSTATE_CONSTANT_VS must be reprogrammed prior to
> + * the next 3DPRIMITIVE command after programming the
> + * 3DSTATE_PUSH_CONSTANT_ALLOC_VS"
> + *
> + * Since 3DSTATE_PUSH_CONSTANT_ALLOC_VS is programmed as part of
> + * pipeline setup, we need to dirty push constants.
> + */
> + cmd_buffer->state.push_constants_dirty |= VK_SHADER_STAGE_ALL_GRAPHICS;
> +}
> +
> static uint32_t
> cmd_buffer_flush_push_constants(struct anv_cmd_buffer *cmd_buffer)
> {
> @@ -384,16 +450,10 @@ genX(cmd_buffer_flush_state)(struct anv_cmd_buffer *cmd_buffer)
>
> anv_batch_emit_batch(&cmd_buffer->batch, &pipeline->batch);
>
> - /* From the BDW PRM for 3DSTATE_PUSH_CONSTANT_ALLOC_VS:
> - *
> - * "The 3DSTATE_CONSTANT_VS must be reprogrammed prior to
> - * the next 3DPRIMITIVE command after programming the
> - * 3DSTATE_PUSH_CONSTANT_ALLOC_VS"
> - *
> - * Since 3DSTATE_PUSH_CONSTANT_ALLOC_VS is programmed as part of
> - * pipeline setup, we need to dirty push constants.
> + /* If the pipeline changed, we may need to re-allocate push constant
> + * space in the URB.
> */
> - cmd_buffer->state.push_constants_dirty |= VK_SHADER_STAGE_ALL_GRAPHICS;
> + cmd_buffer_alloc_push_constants(cmd_buffer);
> }
>
> #if GEN_GEN <= 7
> diff --git a/src/intel/vulkan/genX_pipeline_util.h b/src/intel/vulkan/genX_pipeline_util.h
> index ecbe436..2ed55e0 100644
> --- a/src/intel/vulkan/genX_pipeline_util.h
> +++ b/src/intel/vulkan/genX_pipeline_util.h
> @@ -205,18 +205,6 @@ emit_urb_setup(struct anv_pipeline *pipeline)
> }
> #endif
>
> - unsigned push_start = 0;
> - for (int i = MESA_SHADER_VERTEX; i <= MESA_SHADER_FRAGMENT; i++) {
> - unsigned push_size = pipeline->urb.push_size[i];
> - anv_batch_emit(&pipeline->batch,
> - GENX(3DSTATE_PUSH_CONSTANT_ALLOC_VS), alloc) {
> - alloc._3DCommandSubOpcode = 18 + i;
> - alloc.ConstantBufferOffset = (push_size > 0) ? push_start : 0;
> - alloc.ConstantBufferSize = push_size;
> - }
> - push_start += pipeline->urb.push_size[i];
> - }
> -
> for (int i = MESA_SHADER_VERTEX; i <= MESA_SHADER_GEOMETRY; i++) {
> anv_batch_emit(&pipeline->batch, GENX(3DSTATE_URB_VS), urb) {
> urb._3DCommandSubOpcode = 48 + i;
> --
> 2.5.0.400.gff86faf
>
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