func traceClockNow() traceTime {
	if osHasLowResClock {
		return traceTime(cputicks() / traceTimeDiv)
	}
	return traceTime(nanotime() / traceTimeDiv)
}

// traceClockUnitsPerSecond estimates the number of trace clock units per
// second that elapse.
func traceClockUnitsPerSecond() uint64 {
	if osHasLowResClock {
		// We're using cputicks as our clock, so we need a real estimate.
		return uint64(ticksPerSecond() / traceTimeDiv)
	}