hrtime()

hrtime() is a native PHP function and an PIE extension. As a function, hrtime() returns the high precision time of the system.

HRT represents an acronym of High Resolution Time.

The time is of high precision, but counted from an arbitrary point of time: the value of this function is in calculating differences between two hrtime() calls, rather than the obtained value.

hrtime() is a modern replacement for microtime().

<?php

    $timeStart = hrtime(true);

    // Sleep some time
    usleep(100);

    $timeEnd = hrtime(true);
    $time = $timeEnd - $timeStart;

    echo "Slept for $time micro-seconds\n";

?>

Documentation

See also PHP hrtime Function.

Related : microtime(), Micro-second, sleep