// it would deadlock.
	setThreadCPUProfiler(0)

	for !prof.signalLock.CompareAndSwap(0, 1) {
		osyield()
	}
	if prof.hz.Load() != hz {
		setProcessCPUProfiler(hz)
		prof.hz.Store(hz)
	}
	prof.signalLock.Store(0)

	lock(&sched.lock)
	sched.profilehz = hz
	unlock(&sched.lock)

	if hz != 0 {
		setThreadCPUProfiler(hz)
	}