[Mesa-dev] [PATCH] radv: detect command buffers that do no work and drop them

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

If a buffer is just full of flushes we flush things on command
buffer submission, so don't bother submitting these.

This will reduce some CPU overhead on dota2, which submits a fair
few command streams that don't end up drawing anything.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/amd/vulkan/radv_cmd_buffer.c  |  3 +++
 src/amd/vulkan/radv_device.c      | 14 +++++++++-----
 src/amd/vulkan/radv_meta_buffer.c |  1 +
 src/amd/vulkan/radv_private.h     |  2 ++
 src/amd/vulkan/si_cmd_buffer.c    |  2 +-
 5 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
index f281f33..25b1bd6 100644
--- a/src/amd/vulkan/radv_cmd_buffer.c
+++ b/src/amd/vulkan/radv_cmd_buffer.c
@@ -1277,6 +1277,7 @@ radv_cmd_buffer_flush_state(struct radv_cmd_buffer *cmd_buffer)
 	MAYBE_UNUSED unsigned cdw_max = radeon_check_space(cmd_buffer->device->ws,
 							   cmd_buffer->cs, 4096);
 
+	cmd_buffer->no_draws = false;
 	if ((cmd_buffer->state.vertex_descriptors_dirty || cmd_buffer->state.vb_dirty) &&
 	    cmd_buffer->state.pipeline->num_vertex_attribs) {
 		unsigned vb_offset;
@@ -1592,6 +1593,7 @@ static void  radv_reset_cmd_buffer(struct radv_cmd_buffer *cmd_buffer)
 	cmd_buffer->record_fail = false;
 
 	cmd_buffer->ring_offsets_idx = -1;
+	cmd_buffer->no_draws = true;
 }
 
 VkResult radv_ResetCommandBuffer(
@@ -2423,6 +2425,7 @@ void radv_CmdDrawIndexedIndirectCountAMD(
 static void
 radv_flush_compute_state(struct radv_cmd_buffer *cmd_buffer)
 {
+	cmd_buffer->no_draws = false;
 	radv_emit_compute_pipeline(cmd_buffer);
 	radv_flush_descriptors(cmd_buffer, cmd_buffer->state.compute_pipeline,
 			       VK_SHADER_STAGE_COMPUTE_BIT);
diff --git a/src/amd/vulkan/radv_device.c b/src/amd/vulkan/radv_device.c
index 8a54a2a..fddada4 100644
--- a/src/amd/vulkan/radv_device.c
+++ b/src/amd/vulkan/radv_device.c
@@ -1448,21 +1448,25 @@ VkResult radv_QueueSubmit(
 		cs_array = malloc(sizeof(struct radeon_winsys_cs *) *
 					        pSubmits[i].commandBufferCount);
 
+		int draw_cmds_count = 0;
 		for (uint32_t j = 0; j < pSubmits[i].commandBufferCount; j++) {
 			RADV_FROM_HANDLE(radv_cmd_buffer, cmd_buffer,
 					 pSubmits[i].pCommandBuffers[j]);
 			assert(cmd_buffer->level == VK_COMMAND_BUFFER_LEVEL_PRIMARY);
-
-			cs_array[j] = cmd_buffer->cs;
+			if (cmd_buffer->no_draws == true) {
+				continue;
+			}
+			cs_array[draw_cmds_count] = cmd_buffer->cs;
+			draw_cmds_count++;
 			if ((cmd_buffer->usage_flags & VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT))
 				can_patch = false;
 		}
 
-		for (uint32_t j = 0; j < pSubmits[i].commandBufferCount; j += advance) {
+		for (uint32_t j = 0; j < draw_cmds_count; j += advance) {
 			advance = MIN2(max_cs_submission,
-				       pSubmits[i].commandBufferCount - j);
+				       draw_cmds_count - j);
 			bool b = j == 0;
-			bool e = j + advance == pSubmits[i].commandBufferCount;
+			bool e = j + advance == draw_cmds_count;
 
 			if (queue->device->trace_bo)
 				*queue->device->trace_id_ptr = 0;
diff --git a/src/amd/vulkan/radv_meta_buffer.c b/src/amd/vulkan/radv_meta_buffer.c
index cd2973f..4857d3d 100644
--- a/src/amd/vulkan/radv_meta_buffer.c
+++ b/src/amd/vulkan/radv_meta_buffer.c
@@ -523,6 +523,7 @@ void radv_CmdUpdateBuffer(
 	assert(!(dataSize & 3));
 	assert(!(va & 3));
 
+	cmd_buffer->no_draws = false;
 	if (dataSize < 4096) {
 		cmd_buffer->device->ws->cs_add_buffer(cmd_buffer->cs, dst_buffer->bo, 8);
 
diff --git a/src/amd/vulkan/radv_private.h b/src/amd/vulkan/radv_private.h
index 25ed5de..9a88ce0 100644
--- a/src/amd/vulkan/radv_private.h
+++ b/src/amd/vulkan/radv_private.h
@@ -750,6 +750,8 @@ struct radv_cmd_buffer {
 	uint32_t gsvs_ring_size_needed;
 
 	int ring_offsets_idx; /* just used for verification */
+
+	bool no_draws;
 };
 
 struct radv_image;
diff --git a/src/amd/vulkan/si_cmd_buffer.c b/src/amd/vulkan/si_cmd_buffer.c
index 1c99b22..b94c1f1 100644
--- a/src/amd/vulkan/si_cmd_buffer.c
+++ b/src/amd/vulkan/si_cmd_buffer.c
@@ -828,7 +828,7 @@ static void si_emit_cp_dma_clear_buffer(struct radv_cmd_buffer *cmd_buffer,
 static void si_cp_dma_prepare(struct radv_cmd_buffer *cmd_buffer, uint64_t byte_count,
 			      uint64_t remaining_size, unsigned *flags)
 {
-
+	cmd_buffer->no_draws = false;
 	/* Flush the caches for the first copy only.
 	 * Also wait for the previous CP DMA operations.
 	 */
-- 
2.7.4