profWriteExtra     profIndex = 1 << 33 // overflow or eof waiting
)

func (x *profAtomic) load() profIndex {
	return profIndex(atomic.Load64((*uint64)(x)))
}

func (x *profAtomic) store(new profIndex) {
	atomic.Store64((*uint64)(x), uint64(new))
}

func (x *profAtomic) cas(old, new profIndex) bool {
	return atomic.Cas64((*uint64)(x), uint64(old), uint64(new))
}

func (x profIndex) dataCount() uint32 {