[dpdk-dev] rte_eth_rx_queue_count accuracy
I can not see that code. Can you point out where is it? Thanks On Mon, Sep 21, 2015 at 11:41 PM, Stephen Hemminger < stephen at networkplumber.org> wrote: > On Fri, 18 Sep 2015 11:33:36 +0100 > Alejandro Lucero wrote: > > > 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 > > I have version of this for virtio/vmxnet3 > It is useful when using the interrupt control mode. >
[dpdk-dev] rte_eth_rx_queue_count accuracy
On Fri, 18 Sep 2015 11:33:36 +0100 Alejandro Lucero wrote: > 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 I have version of this for virtio/vmxnet3 It is useful when using the interrupt control mode.
[dpdk-dev] rte_eth_rx_queue_count accuracy
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
