Hi, On 28/07/15 01:10, Ananyev, Konstantin wrote: > Hi Zoltan, > >> -----Original Message----- >> From: Zoltan Kiss [mailto:zoltan.kiss at linaro.org] >> Sent: Monday, July 27, 2015 12:38 PM >> To: Ananyev, Konstantin; Richardson, Bruce; dev at dpdk.org >> Subject: Re: [dpdk-dev] ixgbe vPMD RX functions and buffer number minimum >> requirement >> >> Hi Konstantin, >> >> Thanks! Another question I would have: why does _recv_raw_pkts_vec() >> insist on (nb_pkts > RTE_IXGBE_VPMD_RX_BURST)? Looking at the code it >> should be able to return packets when nb_pkts >= >> RTE_IXGBE_DESCS_PER_LOOP. > > Yes, that seems pretty trivial modification. > Don't know any good reason why it wasn't done that way. > >> The split_flags check in >> ixgbe_recv_scattered_pkts_vec() would be a bit more complicated, and >> therefore maybe would have a tiny performance overhead as well, but I >> don't it would be anything serious. > > I think, if the performance wouldn't be affected, that will be really useful > change. > So it is definitely worth to try. > Probably even _recv_raw_pkts_vec() for first nb_pkts & > ~(RTE_IXGBE_VPMD_RX_BURST - 1), > and then sort of scalar analog for the remainder.
Ok, I'll give it a go. Another question, regarding performance: what setup you used to show a performance difference? I've tried to compare the vector function with the normal bulk alloc with receiving a 10 Gbps stream of 64 bytes UDP packets (and forward them out on the other port), but both yielded ~14 Mpps. I have a i5-4570 CPU @ 3.20GHz, maybe I should limit the clock speed? Regards, Zoltan > Konstantin > >> >> Regards, >> >> Zoltan >> >> >> On 24/07/15 17:43, Ananyev, Konstantin wrote: >>> Hi Zoltan, >>> >>>> -----Original Message----- >>>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Zoltan Kiss >>>> Sent: Friday, July 24, 2015 4:00 PM >>>> To: Richardson, Bruce; dev at dpdk.org >>>> Subject: [dpdk-dev] ixgbe vPMD RX functions and buffer number minimum >>>> requirement >>>> >>>> Hi, >>>> >>>> I was thinking how to handle the situation when you call >>>> rte_eth_rx_burst with less than RTE_IXGBE_VPMD_RX_BURST buffers. In >>>> ODP-DPDK unfortunately we can't force this requirement onto the calling >>>> application. >>>> One idea I had to check in ixgbe_recv_pkts_vec() if nb_pkts < >>>> RTE_IXGBE_VPMD_RX_BURST, and call ixgbe_recv_pkts_bulk_alloc in that >>>> case. Accordingly, in ixgbe_recv_scattered_pkts_vec() we could call >>>> ixgbe_recv_scattered_pkts() in this case. A branch predictor can easily >>>> eliminate the performance penalty of this, and applications can use >>>> whatever burst size feasible for them. >>>> The obvious problem could be whether you can mix the receive functions >>>> this way. I have a feeling it wouldn't fly, but I wanted to ask first >>>> before spending time investigate this option further. >>> >>> No, it is not possible to mix different RX functions, they setup/use >>> ixgbe_rx_queue >>> fields in a different manner. >>> Konstantin >>> >>>> >>>> Regards, >>>> >>>> Zoltan
