My vulkan application exhibits unexpected rendering artifacts, which seems to be varying in size and intensity every frame, even when the transform of the sprite remains unmodified.
Here is what my rendering loop looks like. Actual commands being recorded are being omitted here since the application is fairly large. Anyway, the transfer queue takes care of copy commands (obviously) and the graphics queue does binds and draws commands.
The loop also takes care of eventual images to transition, which get converted once before the transfer queue so that the layout of images in gpu memory becomes VK_LAYOUT_TRANSFER_DST_OPTIMAL, and once after the transfer queue operations so that they get converted to VK_LAYOUT_SHADER_READ_OPTIMAL. Note that transfer and graphics queue are separated on my machine and the case in which they are merged together is not handled in the program yet.
bool end_command_buffer_recording() {
if (vkEndCommandBuffer(m_command_buffers[Renderer::get_current_frame()]) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to end vulkan command buffer recording");
return false;
}
if (m_images_to_transition.get_count()) {
VkCommandBufferBeginInfo begin_info{};
begin_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
begin_info.flags = 0;
begin_info.pInheritanceInfo = nullptr;
m_first_transition_barriers.resize(m_images_to_transition.get_count());
m_second_transition_barriers.resize(m_images_to_transition.get_count() * 2);
// transition setup
Device::QueueFamilyIndices queue_family_indices = m_device.get_queue_family_indices();
if ((vkBeginCommandBuffer(m_first_transition_command_buffer, &begin_info) != VK_SUCCESS) || (vkBeginCommandBuffer(m_second_transition_command_buffers[Renderer::get_current_frame()], &begin_info) != VK_SUCCESS)) {
RGLZ_LOG_ERROR("Failed to begin vulkan transitions command buffer recording");
return false;
}
VkImageMemoryBarrier barrier{};
barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
barrier.subresourceRange.baseMipLevel = 0;
barrier.subresourceRange.levelCount = 1;
barrier.subresourceRange.baseArrayLayer = 0;
barrier.subresourceRange.layerCount = 1;
barrier.srcAccessMask = 0;
barrier.dstAccessMask = 0;
barrier.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
barrier.newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
for (std::uint32_t i = 0; i < m_images_to_transition.get_count(); i++) {
barrier.image = m_images_to_transition[i];
m_first_transition_barriers[i] = barrier;
}
vkCmdPipelineBarrier(m_first_transition_command_buffer, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0, nullptr, 0, nullptr, m_images_to_transition.get_count(), m_first_transition_barriers.get_data());
if (vkEndCommandBuffer(m_first_transition_command_buffer) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to end vulkan first transition command buffer recording");
return false;
}
// second transition acquire
barrier.srcAccessMask = 0;
barrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
barrier.oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
barrier.newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
if (queue_family_indices.transfer_family.has_value()) {
barrier.srcQueueFamilyIndex = queue_family_indices.transfer_family.value();
barrier.dstQueueFamilyIndex = queue_family_indices.graphics_family.value();
std::uint32_t j = 0;
for (std::uint32_t i = m_images_to_transition.get_count(); i < m_second_transition_barriers.get_count(); i++) {
barrier.image = m_images_to_transition[j];
m_second_transition_barriers[i] = barrier;
j++;
}
vkCmdPipelineBarrier(m_second_transition_command_buffers[Renderer::get_current_frame()], VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, nullptr, 0, nullptr, m_images_to_transition.get_count(), m_second_transition_barriers.get_data() + m_images_to_transition.get_count());
}
if (vkEndCommandBuffer(m_second_transition_command_buffers[Renderer::get_current_frame()]) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to end vulkan second transition command buffer recording");
return false;
}
// first transition submit
VkSubmitInfo submit_info{};
submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
submit_info.commandBufferCount = 1;
submit_info.pCommandBuffers = &m_first_transition_command_buffer;
submit_info.waitSemaphoreCount = 0;
submit_info.pWaitSemaphores = nullptr;
submit_info.pWaitDstStageMask = nullptr;
submit_info.signalSemaphoreCount = 1;
submit_info.pSignalSemaphores = &m_first_transition_semaphore;
if (vkQueueSubmit(m_device.get_graphics_queue(), 1, &submit_info, VK_NULL_HANDLE) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to submit vulkan first transition command buffer");
return false;
}
// transfer release
barrier.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
barrier.dstAccessMask = 0;
for (std::uint32_t i = 0; i < m_images_to_transition.get_count(); i++) {
barrier.image = m_images_to_transition[i];
m_second_transition_barriers[i] = barrier;
}
vkCmdPipelineBarrier(m_transfer_command_buffer, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0, nullptr, 0, nullptr, m_images_to_transition.get_count(), m_second_transition_barriers.get_data());
if (vkEndCommandBuffer(m_transfer_command_buffer) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to end vulkan transfer command buffer recording");
return false;
}
// transfer submit
VkPipelineStageFlags transfer_wait_stages[] = {VK_PIPELINE_STAGE_ALL_COMMANDS_BIT};
submit_info = VkSubmitInfo{};
submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
submit_info.commandBufferCount = 1;
submit_info.pCommandBuffers = &m_transfer_command_buffer;
submit_info.waitSemaphoreCount = 1;
submit_info.pWaitSemaphores = &m_first_transition_semaphore;
submit_info.pWaitDstStageMask = transfer_wait_stages;
submit_info.signalSemaphoreCount = 1;
submit_info.pSignalSemaphores = &m_transfer_semaphore;
if (vkQueueSubmit(m_device.get_transfer_queue(), 1, &submit_info, m_transfer_fence) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to submit vulkan transfer command buffer");
return false;
}
// render
VkCommandBuffer command_buffers[] = {m_second_transition_command_buffers[Renderer::get_current_frame()], m_command_buffers[Renderer::get_current_frame()]};
VkSemaphore wait_semaphores[] = {m_transfer_semaphore, m_image_available_semaphores[Renderer::get_current_frame()]};
VkPipelineStageFlags wait_stages[] = {VK_PIPELINE_STAGE_ALL_COMMANDS_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT};
submit_info = VkSubmitInfo{};
submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
submit_info.commandBufferCount = 2;
submit_info.pCommandBuffers = command_buffers;
submit_info.waitSemaphoreCount = 2;
submit_info.pWaitSemaphores = wait_semaphores;
submit_info.pWaitDstStageMask = wait_stages;
submit_info.signalSemaphoreCount = 1;
submit_info.pSignalSemaphores = &m_render_end_semaphores[Renderer::get_current_frame()];
if (vkQueueSubmit(m_device.get_graphics_queue(), 1, &submit_info, m_in_flight_fences[Renderer::get_current_frame()]) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to submit vulkan command buffer");
return false;
}
}
else {
if (vkEndCommandBuffer(m_transfer_command_buffer) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to end vulkan transfer command buffer recording");
return false;
}
VkCommandBufferBeginInfo begin_info{};
begin_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
begin_info.flags = 0;
begin_info.pInheritanceInfo = nullptr;
// transfer
VkSubmitInfo submit_info{};
submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
submit_info.commandBufferCount = 1;
submit_info.pCommandBuffers = &m_transfer_command_buffer;
submit_info.waitSemaphoreCount = 0;
submit_info.pWaitSemaphores = nullptr;
submit_info.pWaitDstStageMask = nullptr;
submit_info.signalSemaphoreCount = 1;
submit_info.pSignalSemaphores = &m_transfer_semaphore;
if (vkQueueSubmit(m_device.get_transfer_queue(), 1, &submit_info, m_transfer_fence) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to submit vulkan transfer command buffer");
return false;
}
// render
VkSemaphore wait_semaphores[] = {m_transfer_semaphore, m_image_available_semaphores[Renderer::get_current_frame()]};
VkPipelineStageFlags wait_stages[] = {VK_PIPELINE_STAGE_ALL_COMMANDS_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT};
submit_info = VkSubmitInfo{};
submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
submit_info.commandBufferCount = 1;
submit_info.pCommandBuffers = &m_command_buffers[Renderer::get_current_frame()];
submit_info.waitSemaphoreCount = 2;
submit_info.pWaitSemaphores = wait_semaphores;
submit_info.pWaitDstStageMask = wait_stages;
submit_info.signalSemaphoreCount = 1;
submit_info.pSignalSemaphores = &m_render_end_semaphores[Renderer::get_current_frame()];
if (vkQueueSubmit(m_device.get_graphics_queue(), 1, &submit_info, m_in_flight_fences[Renderer::get_current_frame()]) != VK_SUCCESS) {
RGLZ_LOG_ERROR("Failed to submit vulkan command buffer");
return false;
}
}
return true;
}
I ran vkconfig and enabled synchronization validation and this is the result.
- [VKERROR]: Validation Error: [ SYNC-HAZARD-WRITE-RACING-READ ] Object 0: handle = 0x5617a6baeb00, type = VK_OBJECT_TYPE_QUEUE; | MessageID = 0xccb77929 | vkQueueSubmit(): Hazard WRITE_RACING_READ for entry 0, VkCommandBuffer 0x5617a88a08d0[], Submitted access info (submitted_usage: SYNC_COPY_TRANSFER_WRITE, command: vkCmdCopyBuffer, command_buffer: VkCommandBuffer 0x5617a8be82b0[], seq_no: 1, reset_no: 7). Access info (prior_usage: SYNC_VERTEX_ATTRIBUTE_INPUT_VERTEX_ATTRIBUTE_READ, read_barriers: VK_PIPELINE_STAGE_2_BOTTOM_OF_PIPE_BIT, queue: VkQueue 0x5617a6b2bbe0[], submit: 5, batch: 0, batch_tag: 45, command: vkCmdDrawIndexed, command_buffer: VkCommandBuffer 0x5617a8bdbed0[], seq_no: 1, reset_no: 3).
- [VKERROR]: Validation Error: [ SYNC-HAZARD-WRITE-AFTER-WRITE ] Object 0: handle = 0x5617a6b2bbe0, type = VK_OBJECT_TYPE_QUEUE; | MessageID = 0x5c0ec5d6 | vkQueueSubmit(): Hazard WRITE_AFTER_WRITE for entry 0, VkCommandBuffer 0x5617a8a56af0[], Submitted access info (submitted_usage: SYNC_IMAGE_LAYOUT_TRANSITION, command: vkCmdBeginRenderPass, seq_no: 1, renderpass: VkRenderPass 0x5617a6b85450[], reset_no: 3). Access info (prior_usage: SYNC_LATE_FRAGMENT_TESTS_DEPTH_STENCIL_ATTACHMENT_WRITE, write_barriers: 0, queue: VkQueue 0x5617a6b2bbe0[], submit: 5, batch: 0, batch_tag: 45, command: vkCmdEndRenderPass, command_buffer: VkCommandBuffer 0x5617a8a6fc50[], seq_no: 3, renderpass: VkRenderPass 0x5617a6b85450[], reset_no: 3).
I seem to be getting this kind of errors a number of times before eventually stopping.
The write racing read is might be due to the fact i have as many regions of gpu memory buffer as frames in flight. However, read and writes should not be overlapping, maybe Vulkan might be complaining about aepeated write and read access in the same buffer, I am not sure.
Maybe I am missing something in my synchronization loop, a memory barrier or something…
PS: Default validation layers do not raise any errors.