Name

VK_KHR_synchronization2 - device extension

VK_KHR_synchronization2

Name String

VK_KHR_synchronization2

Extension Type

Device extension

Registered Extension Number

315

Revision

1

Ratification Status

Ratified

Extension and Version Dependencies

VK_KHR_get_physical_device_properties2 or Vulkan Version 1.1

API Interactions

• Interacts with VK_EXT_blend_operation_advanced
• Interacts with VK_EXT_conditional_rendering
• Interacts with VK_EXT_device_generated_commands
• Interacts with VK_EXT_fragment_density_map
• Interacts with VK_EXT_mesh_shader
• Interacts with VK_EXT_transform_feedback
• Interacts with VK_KHR_acceleration_structure
• Interacts with VK_KHR_fragment_shading_rate
• Interacts with VK_KHR_ray_tracing_pipeline
• Interacts with VK_NV_device_generated_commands
• Interacts with VK_NV_mesh_shader
• Interacts with VK_NV_ray_tracing
• Interacts with VK_NV_shading_rate_image

Deprecation State

• Promoted to Vulkan 1.3

Contact

• Tobias Hector @tobski%0A*Here describe the issue or question you have about the VK_KHR_synchronization2 extension*

Other Extension Metadata

Last Modified Date

2020-12-03

Interactions and External Dependencies

• Interacts with VK_KHR_create_renderpass2

Contributors

• Tobias Hector

Description

This extension modifies the original core synchronization APIs to simplify the interface and improve usability of these APIs. It also adds new pipeline stage and access flag types that extend into the 64-bit range, as we have run out within the 32-bit range. The new flags are identical to the old values within the 32-bit range, with new stages and bits beyond that.

Pipeline stages and access flags are now specified together in memory barrier structures, making the connection between the two more obvious. Additionally, scoping the pipeline stages into the barrier structs allows the use of the MEMORY_READ and MEMORY_WRITE flags without sacrificing precision. The per-stage access flags should be used to disambiguate specific accesses in a given stage or set of stages - for instance, between uniform reads and sampling operations.

Layout transitions have been simplified as well; rather than requiring a different set of layouts for depth/stencil/color attachments, there are generic IMAGE_LAYOUT_ATTACHMENT_OPTIMAL_KHR and IMAGE_LAYOUT_READ_ONLY_OPTIMAL_KHR layouts which are contextually applied based on the image format. For example, for a depth format image, IMAGE_LAYOUT_READ_ONLY_OPTIMAL_KHR is equivalent to IMAGE_LAYOUT_DEPTH_READ_ONLY_OPTIMAL_KHR. IMAGE_LAYOUT_READ_ONLY_OPTIMAL_KHR also functionally replaces IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL.

Events are now more efficient, because they include memory dependency information when you set them on the device. Previously, this information was only known when waiting on an event, so the dependencies could not be satisfied until the wait occurred. That sometimes meant stalling the pipeline when the wait occurred. The new API provides enough information for implementations to satisfy these dependencies in parallel with other tasks.

Queue submission has been changed to wrap command buffers and semaphores in extensible structures, which incorporate changes from Vulkan 1.1, VK_KHR_device_group, and VK_KHR_timeline_semaphore. This also adds a pipeline stage to the semaphore signal operation, mirroring the existing pipeline stage specification for wait operations.

Other miscellaneous changes include:

• Events can now be specified as interacting only with the device, allowing more efficient access to the underlying object.

• Image memory barriers that do not perform an image layout transition can be specified by setting oldLayout equal to newLayout.

  • E.g. the old and new layout can both be set to IMAGE_LAYOUT_UNDEFINED, without discarding data in the image.
• Queue family ownership transfer parameters are simplified in some cases.
• Extensions with commands or functions with a PipelineStageFlags or PipelineStageFlagBits parameter have had those APIs replaced with equivalents using PipelineStageFlags2KHR.
• The new event and barrier interfaces are now more extensible for future changes.
• Relevant pipeline stage masks can now be specified as empty with the new PIPELINE_STAGE_NONE_KHR and PIPELINE_STAGE_2_NONE_KHR values.
• MemoryBarrier2KHR can be chained to SubpassDependency2, overriding the original 32-bit stage and access masks.

New Base Types

• Flags64

New Commands

• cmdPipelineBarrier2KHR

• cmdResetEvent2KHR
• cmdSetEvent2KHR
• cmdWaitEvents2KHR
• cmdWriteTimestamp2KHR
• queueSubmit2KHR

New Structures

• BufferMemoryBarrier2KHR

• CommandBufferSubmitInfoKHR
• DependencyInfoKHR
• ImageMemoryBarrier2KHR
• SemaphoreSubmitInfoKHR
• SubmitInfo2KHR

• Extending PhysicalDeviceFeatures2, DeviceCreateInfo:

  • PhysicalDeviceSynchronization2FeaturesKHR

• Extending SubpassDependency2:

  • MemoryBarrier2KHR

New Enums

• AccessFlagBits2KHR

• PipelineStageFlagBits2KHR
• SubmitFlagBitsKHR

New Bitmasks

• AccessFlags2KHR

• PipelineStageFlags2KHR
• SubmitFlagsKHR

New Enum Constants

• KHR_SYNCHRONIZATION_2_EXTENSION_NAME

• KHR_SYNCHRONIZATION_2_SPEC_VERSION

• Extending AccessFlagBits:

  • ACCESS_NONE_KHR

• Extending AccessFlagBits2:

  • ACCESS_2_COLOR_ATTACHMENT_READ_BIT_KHR
  • ACCESS_2_COLOR_ATTACHMENT_WRITE_BIT_KHR
  • ACCESS_2_DEPTH_STENCIL_ATTACHMENT_READ_BIT_KHR
  • ACCESS_2_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT_KHR
  • ACCESS_2_HOST_READ_BIT_KHR
  • ACCESS_2_HOST_WRITE_BIT_KHR
  • ACCESS_2_INDEX_READ_BIT_KHR
  • ACCESS_2_INDIRECT_COMMAND_READ_BIT_KHR
  • ACCESS_2_INPUT_ATTACHMENT_READ_BIT_KHR
  • ACCESS_2_MEMORY_READ_BIT_KHR
  • ACCESS_2_MEMORY_WRITE_BIT_KHR
  • ACCESS_2_NONE_KHR
  • ACCESS_2_SHADER_READ_BIT_KHR
  • ACCESS_2_SHADER_SAMPLED_READ_BIT_KHR
  • ACCESS_2_SHADER_STORAGE_READ_BIT_KHR
  • ACCESS_2_SHADER_STORAGE_WRITE_BIT_KHR
  • ACCESS_2_SHADER_WRITE_BIT_KHR
  • ACCESS_2_TRANSFER_READ_BIT_KHR
  • ACCESS_2_TRANSFER_WRITE_BIT_KHR
  • ACCESS_2_UNIFORM_READ_BIT_KHR
  • ACCESS_2_VERTEX_ATTRIBUTE_READ_BIT_KHR

• Extending EventCreateFlagBits:

  • EVENT_CREATE_DEVICE_ONLY_BIT_KHR

• Extending ImageLayout:

  • IMAGE_LAYOUT_ATTACHMENT_OPTIMAL_KHR
  • IMAGE_LAYOUT_READ_ONLY_OPTIMAL_KHR

• Extending PipelineStageFlagBits:

  • PIPELINE_STAGE_NONE_KHR

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_ALL_COMMANDS_BIT_KHR
  • PIPELINE_STAGE_2_ALL_GRAPHICS_BIT_KHR
  • PIPELINE_STAGE_2_ALL_TRANSFER_BIT_KHR
  • PIPELINE_STAGE_2_BLIT_BIT_KHR
  • PIPELINE_STAGE_2_BOTTOM_OF_PIPE_BIT_KHR
  • PIPELINE_STAGE_2_CLEAR_BIT_KHR
  • PIPELINE_STAGE_2_COLOR_ATTACHMENT_OUTPUT_BIT_KHR
  • PIPELINE_STAGE_2_COMPUTE_SHADER_BIT_KHR
  • PIPELINE_STAGE_2_COPY_BIT_KHR
  • PIPELINE_STAGE_2_DRAW_INDIRECT_BIT_KHR
  • PIPELINE_STAGE_2_EARLY_FRAGMENT_TESTS_BIT_KHR
  • PIPELINE_STAGE_2_FRAGMENT_SHADER_BIT_KHR
  • PIPELINE_STAGE_2_GEOMETRY_SHADER_BIT_KHR
  • PIPELINE_STAGE_2_HOST_BIT_KHR
  • PIPELINE_STAGE_2_INDEX_INPUT_BIT_KHR
  • PIPELINE_STAGE_2_LATE_FRAGMENT_TESTS_BIT_KHR
  • PIPELINE_STAGE_2_NONE_KHR
  • PIPELINE_STAGE_2_PRE_RASTERIZATION_SHADERS_BIT_KHR
  • PIPELINE_STAGE_2_RESOLVE_BIT_KHR
  • PIPELINE_STAGE_2_TESSELLATION_CONTROL_SHADER_BIT_KHR
  • PIPELINE_STAGE_2_TESSELLATION_EVALUATION_SHADER_BIT_KHR
  • PIPELINE_STAGE_2_TOP_OF_PIPE_BIT_KHR
  • PIPELINE_STAGE_2_TRANSFER_BIT_KHR
  • PIPELINE_STAGE_2_VERTEX_ATTRIBUTE_INPUT_BIT_KHR
  • PIPELINE_STAGE_2_VERTEX_INPUT_BIT_KHR
  • PIPELINE_STAGE_2_VERTEX_SHADER_BIT_KHR

• Extending StructureType:

  • STRUCTURE_TYPE_BUFFER_MEMORY_BARRIER_2_KHR
  • STRUCTURE_TYPE_COMMAND_BUFFER_SUBMIT_INFO_KHR
  • STRUCTURE_TYPE_DEPENDENCY_INFO_KHR
  • STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER_2_KHR
  • STRUCTURE_TYPE_MEMORY_BARRIER_2_KHR
  • STRUCTURE_TYPE_PHYSICAL_DEVICE_SYNCHRONIZATION_2_FEATURES_KHR
  • STRUCTURE_TYPE_SEMAPHORE_SUBMIT_INFO_KHR
  • STRUCTURE_TYPE_SUBMIT_INFO_2_KHR

• Extending SubmitFlagBits:

  • SUBMIT_PROTECTED_BIT_KHR

If VK_EXT_blend_operation_advanced is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_COLOR_ATTACHMENT_READ_NONCOHERENT_BIT_EXT

If VK_EXT_conditional_rendering is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_CONDITIONAL_RENDERING_READ_BIT_EXT

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_CONDITIONAL_RENDERING_BIT_EXT

If VK_EXT_device_generated_commands is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_COMMAND_PREPROCESS_READ_BIT_EXT
  • ACCESS_2_COMMAND_PREPROCESS_WRITE_BIT_EXT

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_COMMAND_PREPROCESS_BIT_EXT

If VK_EXT_fragment_density_map is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_FRAGMENT_DENSITY_MAP_READ_BIT_EXT

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_FRAGMENT_DENSITY_PROCESS_BIT_EXT

If VK_EXT_mesh_shader is supported:

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_MESH_SHADER_BIT_EXT
  • PIPELINE_STAGE_2_TASK_SHADER_BIT_EXT

If VK_EXT_transform_feedback is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_TRANSFORM_FEEDBACK_COUNTER_READ_BIT_EXT
  • ACCESS_2_TRANSFORM_FEEDBACK_COUNTER_WRITE_BIT_EXT
  • ACCESS_2_TRANSFORM_FEEDBACK_WRITE_BIT_EXT

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_TRANSFORM_FEEDBACK_BIT_EXT

If VK_KHR_acceleration_structure is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_ACCELERATION_STRUCTURE_READ_BIT_KHR
  • ACCESS_2_ACCELERATION_STRUCTURE_WRITE_BIT_KHR

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_ACCELERATION_STRUCTURE_BUILD_BIT_KHR

If VK_KHR_fragment_shading_rate is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_FRAGMENT_SHADING_RATE_ATTACHMENT_READ_BIT_KHR

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT_KHR

If VK_KHR_ray_tracing_pipeline is supported:

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_RAY_TRACING_SHADER_BIT_KHR

If VK_NV_device_generated_commands is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_COMMAND_PREPROCESS_READ_BIT_NV
  • ACCESS_2_COMMAND_PREPROCESS_WRITE_BIT_NV

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_COMMAND_PREPROCESS_BIT_NV

If VK_NV_mesh_shader is supported:

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_MESH_SHADER_BIT_NV
  • PIPELINE_STAGE_2_TASK_SHADER_BIT_NV

If VK_NV_ray_tracing is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_ACCELERATION_STRUCTURE_READ_BIT_NV
  • ACCESS_2_ACCELERATION_STRUCTURE_WRITE_BIT_NV

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_ACCELERATION_STRUCTURE_BUILD_BIT_NV
  • PIPELINE_STAGE_2_RAY_TRACING_SHADER_BIT_NV

If VK_NV_shading_rate_image is supported:

• Extending AccessFlagBits2:

  • ACCESS_2_SHADING_RATE_IMAGE_READ_BIT_NV

• Extending PipelineStageFlagBits2:

  • PIPELINE_STAGE_2_SHADING_RATE_IMAGE_BIT_NV

Promotion to Vulkan 1.3

Vulkan APIs in this extension are included in core Vulkan 1.3, with the KHR suffix omitted. External interactions defined by this extension, such as SPIR-V token names, retain their original names. The original Vulkan API names are still available as aliases of the core functionality.

Examples

See https://github.com/KhronosGroup/Vulkan-Docs/wiki/Synchronization-Examples

Version History

• Revision 1, 2020-12-03 (Tobias Hector)

  • Internal revisions

See Also

No cross-references are available

Document Notes

For more information, see the Vulkan Specification.

This page is a generated document. Fixes and changes should be made to the generator scripts, not directly.