// That is, decrementing the global progress meter R by rDecrement.
const highR = rDecrement + rDecrement/2

// advanceEpoch subtracts rDecrement from the global progress meter R
// and all the readings that have been taked from that meter.
// The now and incrR parameters are only used to add info to the log messages.
func (qs *queueSet) advanceEpoch(ctx context.Context, now time.Time, incrR fqrequest.SeatSeconds) {