Intel® Graphics Performance Analyzers User Guide

ID 767266
Date 12/15/2022
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

Clock Domain API

Some applications require the capability to trace events with user-defined timestamps and frequencies different from the timestamps and frequencies generated by a CPU, for example, to instrument events that occur on a GPU. For the purpose you can create a clock domain.

To create a clock domain, use the following primitive:

__itt_clock_domain * ITTAPI __itt_clock_domain_create(__itt_get_clock_info_fn fn, void* fn_data)

Parameters of the primitive:

[in]

fn

Pointer to a callback function that retrieves alternative CPU timestamps and frequencies and stores the timestamps and frequencies data in the clock domain structure field __itt_clock_info.

[in]

fn_data

Argument of a callback function; can be NULL.

Tasks issued from different clock domains are shown on the same timeline by synchronizing a referenced clock domain base timestamp captured at the moment of clock domain creation and a CPU timestamp captured at the same time.

To recalculate clock domain base timestamps and frequencies, if necessary, for example, when a GPU frequency changes, use the following primitive:

__itt_clock_domain_reset()