Re: [dpdk-dev] ixgbe vPMD RX functions and buffer number minimum requirement

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Zoltan,

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zoltan Kiss
> Sent: Friday, July 24, 2015 4:00 PM
> To: Richardson, Bruce; dev@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