vkCmdWriteTimestamp2KHR(3)

# vkCmdWriteTimestamp2KHR(3) Manual Page

## Name

vkCmdWriteTimestamp2KHR - Write a device timestamp into a query object

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## C Specification

To request a timestamp, call:

    // Provided by VK_KHR_synchronization2
    void vkCmdWriteTimestamp2KHR(
        VkCommandBuffer                             commandBuffer,
        VkPipelineStageFlags2KHR                    stage,
        VkQueryPool                                 queryPool,
        uint32_t                                    query);

## Parameters

- `commandBuffer` is the command buffer into which the command will be recorded.

- `stage` specifies a stage of the pipeline.

- `queryPool` is the query pool that will manage the timestamp.

- `query` is the query within the query pool that will contain the timestamp.

## Description

When `vkCmdWriteTimestamp2KHR` is submitted to a queue, it defines an execution dependency on commands that were submitted before it, and writes a timestamp to a query pool.

The first synchronization scope includes all commands that occur earlier in submission order. The synchronization scope is limited to operations on the pipeline stage specified by `pipelineStage`.

The second synchronization scope includes only the timestamp write operation.

When the timestamp value is written, the availability status of the query is set to available.

| Note If an implementation is unable to detect completion and latch the timer at any specific stage of the pipeline, it may instead do so at any logically later stage.

Timestamps may only be meaningfully compared if they are written by commands submitted to the same queue.

| Note An example of such a comparison is determining the execution time of a sequence of commands.

If `vkCmdWriteTimestamp2KHR` is called while executing a render pass instance that has multiview enabled, the timestamp uses N consecutive query indices in the query pool (starting at `query`) where N is the number of bits set in the view mask of the subpass the command is executed in. The resulting query values are determined by an implementation-dependent choice of one of the following behaviors:

- The first query is a timestamp value and (if more than one bit is set in the view mask) zero is written to the remaining queries. If two timestamps are written in the same subpass, the sum of the execution time of all views between those commands is the difference between the first query written by each command.

- All N queries are timestamp values. If two timestamps are written in the same subpass, the sum of the execution time of all views between those commands is the sum of the difference between corresponding queries written by each command. The difference between corresponding queries may be the execution time of a single view.

In either case, the application can sum the differences between all N queries to determine the total execution time.

Valid Usage

- VUID-vkCmdWriteTimestamp2KHR-stage-03929
  If the geometry shaders feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_GEOMETRY_SHADER_BIT_KHR`

- VUID-vkCmdWriteTimestamp2KHR-stage-03930
  If the tessellation shaders feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_TESSELLATION_CONTROL_SHADER_BIT_KHR` or `VK_PIPELINE_STAGE_2_TESSELLATION_EVALUATION_SHADER_BIT_KHR`

- VUID-vkCmdWriteTimestamp2KHR-stage-03931
  If the conditional rendering feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_CONDITIONAL_RENDERING_BIT_EXT`

- VUID-vkCmdWriteTimestamp2KHR-stage-03932
  If the fragment density map feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_FRAGMENT_DENSITY_PROCESS_BIT_EXT`

- VUID-vkCmdWriteTimestamp2KHR-stage-03933
  If the transform feedback feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_TRANSFORM_FEEDBACK_BIT_EXT`

- VUID-vkCmdWriteTimestamp2KHR-stage-03934
  If the mesh shaders feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_MESH_SHADER_BIT_NV`

- VUID-vkCmdWriteTimestamp2KHR-stage-03935
  If the task shaders feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_TASK_SHADER_BIT_NV`

- VUID-vkCmdWriteTimestamp2KHR-stage-03936
  If the shading rate image feature is not enabled, `stage` must not contain `VK_PIPELINE_STAGE_2_SHADING_RATE_IMAGE_BIT_NV`

- VUID-vkCmdWriteTimestamp2KHR-synchronization2-03858
  The `synchronization2` feature must be enabled

- VUID-vkCmdWriteTimestamp2KHR-stage-03859
  `stage` must only include a single pipeline stage

- VUID-vkCmdWriteTimestamp2KHR-stage-03860
  `stage` must only include stages valid for the queue family that was used to create the command pool that `commandBuffer` was allocated from

- VUID-vkCmdWriteTimestamp2KHR-queryPool-03861
  `queryPool` must have been created with a `queryType` of `VK_QUERY_TYPE_TIMESTAMP`

- VUID-vkCmdWriteTimestamp2KHR-queryPool-03862
  The query identified by `queryPool` and `query` must be unavailable

- VUID-vkCmdWriteTimestamp2KHR-timestampValidBits-03863
  The command pool’s queue family must support a non-zero `timestampValidBits`

- VUID-vkCmdWriteTimestamp2KHR-None-03864
  All queries used by the command must be unavailable

- VUID-vkCmdWriteTimestamp2KHR-query-03865
  If `vkCmdWriteTimestamp2KHR` is called within a render pass instance, the sum of `query` and the number of bits set in the current subpass’s view mask must be less than or equal to the number of queries in `queryPool`

Valid Usage (Implicit)

- VUID-vkCmdWriteTimestamp2KHR-commandBuffer-parameter
  `commandBuffer` must be a valid VkCommandBuffer handle

- VUID-vkCmdWriteTimestamp2KHR-stage-parameter
  `stage` must be a valid combination of VkPipelineStageFlagBits2KHR values

- VUID-vkCmdWriteTimestamp2KHR-stage-requiredbitmask
  `stage` must not be `0`

- VUID-vkCmdWriteTimestamp2KHR-queryPool-parameter
  `queryPool` must be a valid VkQueryPool handle

- VUID-vkCmdWriteTimestamp2KHR-commandBuffer-recording
  `commandBuffer` must be in the recording state

- VUID-vkCmdWriteTimestamp2KHR-commandBuffer-cmdpool
  The `VkCommandPool` that `commandBuffer` was allocated from must support transfer, graphics, or compute operations

- VUID-vkCmdWriteTimestamp2KHR-commonparent
  Both of `commandBuffer`, and `queryPool` must have been created, allocated, or retrieved from the same VkDevice

Host Synchronization

- Host access to `commandBuffer` must be externally synchronized

- Host access to the `VkCommandPool` that `commandBuffer` was allocated from must be externally synchronized

Command Properties

Command Buffer Levels | Render Pass Scope | Supported Queue Types | Pipeline Type
--- | --- | --- | ---
Primary Secondary | Both | Transfer Graphics Compute | Transfer

## See Also

VkCommandBuffer, VkPipelineStageFlags2KHR, VkQueryPool

## Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright 2014-2021 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0