vkCmdWriteTimestamp2(3)

C Specification

To request a timestamp and write the value to memory, call:

// Provided by VK_KHR_synchronization2
void vkCmdWriteTimestamp2KHR(
    VkCommandBuffer                             commandBuffer,
    VkPipelineStageFlags2                       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 stage.

The second synchronization scope includes only the timestamp write operation.

Note

Implementations may write the timestamp at any stage that is logically later than stage.

Any timestamp write that happens-after another timestamp write in the same submission must not have a lower value unless its value overflows the maximum supported integer bit width of the query. If VK_EXT_calibrated_timestamps is enabled, this extends to timestamp writes across all submissions on the same logical device: any timestamp write that happens-after another must not have a lower value unless its value overflows the maximum supported integer bit width of the query. Timestamps written by this command must be in the VK_TIME_DOMAIN_DEVICE_EXT time domain. If an overflow occurs, the timestamp value must wrap back to zero.

Note

Comparisons between timestamps should be done between timestamps where they are guaranteed to not decrease. For example, subtracting an older timestamp from a newer one to determine the execution time of a sequence of commands is only a reliable measurement if the two timestamp writes were performed in the same submission, or if the writes were performed on the same logical device and VK_EXT_calibrated_timestamps is enabled.

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-vkCmdWriteTimestamp2-stage-03929
If the geometryShader feature is not enabled, stage must not contain VK_PIPELINE_STAGE_2_GEOMETRY_SHADER_BIT
VUID-vkCmdWriteTimestamp2-stage-03930
If the tessellationShader feature is not enabled, stage must not contain VK_PIPELINE_STAGE_2_TESSELLATION_CONTROL_SHADER_BIT or VK_PIPELINE_STAGE_2_TESSELLATION_EVALUATION_SHADER_BIT
VUID-vkCmdWriteTimestamp2-stage-07317
If the attachmentFragmentShadingRate feature is not enabled, stage must not contain VK_PIPELINE_STAGE_2_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT_KHR
VUID-vkCmdWriteTimestamp2-synchronization2-03858
The synchronization2 feature must be enabled
VUID-vkCmdWriteTimestamp2-stage-03859
stage must only include a single pipeline stage
VUID-vkCmdWriteTimestamp2-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-vkCmdWriteTimestamp2-queryPool-03861
queryPool must have been created with a queryType of VK_QUERY_TYPE_TIMESTAMP
VUID-vkCmdWriteTimestamp2-timestampValidBits-03863
The command pool’s queue family must support a non-zero timestampValidBits
VUID-vkCmdWriteTimestamp2-query-04903
query must be less than the number of queries in queryPool
VUID-vkCmdWriteTimestamp2-None-03864
All queries used by the command must be unavailable
VUID-vkCmdWriteTimestamp2-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-vkCmdWriteTimestamp2-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle
VUID-vkCmdWriteTimestamp2-stage-parameter
stage must be a valid combination of VkPipelineStageFlagBits2 values
VUID-vkCmdWriteTimestamp2-queryPool-parameter
queryPool must be a valid VkQueryPool handle
VUID-vkCmdWriteTimestamp2-commandBuffer-recording
commandBuffer must be in the recording state
VUID-vkCmdWriteTimestamp2-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support transfer, graphics, or compute operations
VUID-vkCmdWriteTimestamp2-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