> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Zhao1, Wei > Sent: Thursday, July 16, 2020 10:50 AM > > Hi, > > > -----Original Message----- > > From: Morten Brørup <m...@smartsharesystems.com> > > Sent: Thursday, July 16, 2020 12:03 AM > > To: Zhao1, Wei <wei.zh...@intel.com>; Guo, Jia <jia....@intel.com> > > Cc: dev@dpdk.org; Thomas Monjalon <tho...@monjalon.net>; Yigit, > Ferruh > > <ferruh.yi...@intel.com>; Andrew Rybchenko > <arybche...@solarflare.com> > > Subject: ixgbe vector rx does not conform to rte_eth_rx_burst() API > > > > Wei, Jeff, > > > > For the ixgbe driver using vector functions, i.e. > ixgbe_recv_pkts_vec(), calling > > rte_eth_rx_burst() with nb_pkts > RTE_IXGBE_MAX_RX_BURST only returns > > RTE_IXGBE_MAX_RX_BURST packets. E.g. calling rte_eth_rx_burst() with > > nb_pkts=64 only returns 32 packets. > > > > > > The API description of rte_eth_rx_burst() says: > > > > <quote> > > The rte_eth_rx_burst() function returns the number of packets > actually > > retrieved, which is the number of rte_mbuf data structures > effectively supplied > > into the rx_pkts array. A return value equal to nb_pkts indicates > that the RX > > queue contained at least rx_pkts packets, and this is likely to > signify that other > > received packets remain in the input queue. Applications implementing > a > > "retrieve as much received packets as possible" policy can check this > specific > > case and keep invoking the rte_eth_rx_burst() function until a value > less than > > nb_pkts is returned. > > </quote> > > > > The driver implementation does not conform to the documented behavior > for > > "retrieve as much received packets as possible" applications. > > It seems not an issue, this function has comment bellow, it is design > work in that way. > > > /* > * vPMD receive routine, only accept(nb_pkts >= > RTE_IXGBE_DESCS_PER_LOOP) > * > * Notice: > * - nb_pkts < RTE_IXGBE_DESCS_PER_LOOP, just return no packet > * - nb_pkts > RTE_IXGBE_MAX_RX_BURST, only scan RTE_IXGBE_MAX_RX_BURST > * numbers of DD bit > * - floor align nb_pkts to a RTE_IXGBE_DESC_PER_LOOP power-of-two > */ >
I noticed this already. And yes, ixgbe_recv_pkts_vec() does what its comments says. However, when ixgbe_recv_pkts_vec() is used as the driver's implementation of the rte_eth_rx_burst() function call, the rte_eth_rx_burst() function does not do what is expected of the rte_eth_rx_burst() function. The implementation must conform to the API that it implements. If you don't want to update the ixgbe_recv_pkts_vec() function, I propose that you add a wrapper function that calls ixgbe_recv_pkts_vec() repeatedly, and use the wrapper function as the implementation of the rte_eth_rx_burst() function.
