// goroutine that is coordinating the goroutine profile (running on its own
// stack), or from the scheduler in preparation to execute gp1 (running on the
// system stack).
func doRecordGoroutineProfile(gp1 *g, pcbuf []uintptr) {
	if readgstatus(gp1) == _Grunning {
		print("doRecordGoroutineProfile gp1=", gp1.goid, "\n")
		throw("cannot read stack of running goroutine")
	}

	offset := int(goroutineProfile.offset.Add(1)) - 1

		n = max
	}
	if n > int32(len(pp.runq))/2 {
		n = int32(len(pp.runq)) / 2
	}

	sched.runqsize -= n

	gp := sched.runq.pop()
	n--
	for ; n > 0; n-- {
		gp1 := sched.runq.pop()
		runqput(pp, gp1, false)
	}
	return gp
}

// pMask is an atomic bitstring with one bit per P.
type pMask []uint32

// read returns true if P id's bit is set.