I have seen the API definition says nothing about accuracy but some PMD implementations sacrifice accuracy for the sake of performance. If I'm not understanding the code wrongly i40e and ixgbe check DD bit just for the first descriptor in a group of 4, and they take all of them as used if the first descriptor is used.
By other hand, they do a "heavy" calculation when the descriptor ring wraps which does not make sense (to me) if same performance goal is used. There are PMDs not supporting this option and I can not see any app or example using it so I do not know how important is this function, its accuracy and its performance impact. Can someone comment on this? Thanks
