To request a timestamp, call:
// Provided by VK_KHR_synchronization2 void vkCmdWriteTimestamp2KHR( VkCommandBuffer commandBuffer, VkPipelineStageFlags2KHR stage, VkQueryPool queryPool, uint32_t query);
commandBufferis the command buffer into which the command will be recorded.
stagespecifies a stage of the pipeline.
queryPoolis the query pool that will manage the timestamp.
queryis the query within the query pool that will contain the timestamp.
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 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.
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.
Comparisons between timestamps are not meaningful if the timestamps are written by commands submitted to different queues.
An example of such a comparison is subtracting an older timestamp from a newer one to determine the execution time of a sequence of commands.
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
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.
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.