C Specification

To query device and host timestamps, call the function:

cl_int clGetDeviceAndHostTimer(
    cl_device_id device,
    cl_ulong* device_timestamp,
    cl_ulong* host_timestamp);

Parameters

  • device is a device returned by clGetDeviceIDs.

  • device_timestamp will be updated with the value of the device timer in nanoseconds. The resolution of the timer is the same as the device profiling timer returned by clGetDeviceInfo and the CL_​DEVICE_​PROFILING_​TIMER_​RESOLUTION query.

  • host_timestamp will be updated with the value of the host timer in nanoseconds at the closest possible point in time to that at which device_timer was returned. The resolution of the timer may be queried via clGetPlatformInfo and the flag CL_​PLATFORM_​HOST_​TIMER_​RESOLUTION.

Description

clGetDeviceAndHostTimer returns a reasonably synchronized pair of timestamps from the device timer and the host timer as seen by device. Implementations may need to execute this query with a high latency in order to provide reasonable synchronization of the timestamps. The host timestamp and device timestamp returned by this function and clGetHostTimer each have an implementation defined timebase. The timestamps will always be in their respective timebases regardless of which query function is used. The timestamp returned from clGetEventProfilingInfo for an event on a device and a device timestamp queried from the same device will always be in the same timebase.

clGetDeviceAndHostTimer will return CL_​SUCCESS with a time value in host_timestamp if provided. Otherwise, it returns one of the following errors:

  • CL_​INVALID_​DEVICE if device is not a valid device.

  • CL_​INVALID_​VALUE if host_timestamp or device_timestamp is NULL.

  • CL_​OUT_​OF_​RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.

  • CL_​OUT_​OF_​HOST_​MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

See Also

Document Notes

For more information, see the OpenCL Specification

This page is extracted from the OpenCL Specification. Fixes and changes should be made to the Specification, not directly.

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