C Specification

In order to be able to correlate the time a particular operation took place at on timelines of different time domains (e.g. a device operation vs a host operation), Vulkan allows querying calibrated timestamps from multiple time domains.

To query calibrated timestamps from a set of time domains, call:

VkResult vkGetCalibratedTimestampsEXT(
    VkDevice                                    device,
    uint32_t                                    timestampCount,
    const VkCalibratedTimestampInfoEXT*         pTimestampInfos,
    uint64_t*                                   pTimestamps,
    uint64_t*                                   pMaxDeviation);

Parameters

  • device is the logical device used to perform the query.

  • timestampCount is the number of timestamps to query.

  • pTimestampInfos is a pointer to an array of timestampCount VkCalibratedTimestampInfoEXT structures, describing the time domains the calibrated timestamps should be captured from.

  • pTimestamps is a pointer to an array of timestampCount 64-bit unsigned integer values in which the requested calibrated timestamp values are returned.

  • pMaxDeviation is a pointer to a 64-bit unsigned integer value in which the strictly positive maximum deviation, in nanoseconds, of the calibrated timestamp values is returned.

Description

Note

The maximum deviation may vary between calls to vkGetCalibratedTimestampsEXT even for the same set of time domains due to implementation and platform specific reasons. It is the application’s responsibility to assess whether the returned maximum deviation makes the timestamp values suitable for any particular purpose and can choose to re-issue the timestamp calibration call pursuing a lower devation value.

Calibrated timestamp values can be extrapolated to estimate future coinciding timestamp values, however, depending on the nature of the time domains and other properties of the platform extrapolating values over a sufficiently long period of time may no longer be accurate enough to fit any particular purpose so applications are expected to re-calibrate the timestamps on a regular basis.

Valid Usage (Implicit)
  • device must be a valid VkDevice handle

  • pTimestampInfos must be a valid pointer to an array of timestampCount valid VkCalibratedTimestampInfoEXT structures

  • pTimestamps must be a valid pointer to an array of timestampCount uint64_t values

  • pMaxDeviation must be a valid pointer to a uint64_t value

  • timestampCount must be greater than 0

Return Codes
On success, this command returns
  • VK_SUCCESS

On failure, this command returns
  • VK_ERROR_OUT_OF_HOST_MEMORY

  • VK_ERROR_OUT_OF_DEVICE_MEMORY

See Also

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 (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.