vkGetPastPresentationTimingGOOGLE

The implementation will maintain a limited amount of history of timing information about previous presents. Because of the asynchronous nature of the presentation engine, the timing information for a given vkQueuePresentKHR command will become available some time later. These time values can be asynchronously queried, and will be returned if available. All time values are in nanoseconds, relative to a monotonically-increasing clock (e.g. CLOCK_MONOTONIC (see clock_gettime(2)) on Android and Linux).

To asynchronously query the presentation engine, for newly-available timing information about one or more previous presents to a given swapchain, call:

VkResult vkGetPastPresentationTimingGOOGLE(
    VkDevice device,
    VkSwapchainKHR swapchain,
    uint32_t* pPresentationTimingCount,
    VkPastPresentationTimingGOOGLE* pPresentationTimings);

• device is the device associated with swapchain.
• swapchain is the swapchain to obtain presentation timing information duration for.
• pPresentationTimingCount is a pointer to an integer related to the number of VkPastPresentationTimingGOOGLE structures to query, as described below.
• pPresentationTimings is either NULL or a pointer to an array of VkPastPresentationTimingGOOGLE structures.

If pPresentationTimings is NULL, then the number of newly-available timing records for the given swapchain is returned in pPresentationTimingCount. Otherwise, pPresentationTimingCount must point to a variable set by the user to the number of elements in the pPresentationTimings array, and on return the variable is overwritten with the number of structures actually written to pPresentationTimings. If the value of pPresentationTimingCount is less than the number of newly-available timing records, at most pPresentationTimingCount structures will be written, and VK_INCOMPLETE will be returned instead of VK_SUCCESS, to indicate that not all the available timing records were returned.