Re: ixgbe vPMD RX functions and buffer number minimum requirement

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