# vkGetCalibratedTimestampsEXT(3) Manual Page

## Name

vkGetCalibratedTimestampsEXT - Query calibrated timestamps

## 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

VkCalibratedTimestampInfoEXT, VkDevice

## 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 (c) 2014-2020 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.