vkCmdWriteTimestamp

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

void vkCmdWriteTimestamp(
    VkCommandBuffer commandBuffer,
    VkPipelineStageFlagBits pipelineStage,
    VkQueryPool queryPool,
    uint32_t query);

• commandBuffer is the command buffer into which the command will be recorded.
• pipelineStage is a VkPipelineStageFlagBits value, specifying 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.

When vkCmdWriteTimestamp 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.

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_KHR_calibrated_timestamps or 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_KHR

time domain. If an overflow occurs, the timestamp value must wrap back to zero.

If vkCmdWriteTimestamp 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.