code: func (r *renoState) reduceSlowStartThreshold() {
  	r.s.sndSsthresh = r.s.outstanding / 2
  	if r.s.sndSsthresh < 2 {
  		r.s.sndSsthresh = 2
  	}
  
  }
docs: // reduceSlowStartThreshold reduces the slow-start threshold per RFC 5681,
  // page 6, eq. 4. It is called when we detect congestion in the network.