[dpdk-dev] Packet Rx issue with DPDK1.8

[Bruce Richardson]

On Thu, Jan 08, 2015 at 01:40:54PM +0530, Prashant Upadhyaya wrote:
> Hi,
> 
> I am migrating from DPDK1.7 to DPDK1.8.
> My application works fine with DPDK1.7.
> I am using 10 Gb Intel 82599 NIC.
> I have jumbo frames enabled, with max_rx_pkt_len = 10232
> My mbuf dataroom size is 2048+headroom
> So naturally the ixgbe_recv_scattered_pkts driver function is triggered for
> receiving.
> This works with DPDK1.7 and my app receives packets.
> However, it does not work with DPDK1.8 somehow.I don't receive any packets.
> 
> So, I increased the mbuf data room size in my application to a higher value
> so that the function ixgbe_recv_scattered_pkts is not enabled (I believe
> ixgbe_recv_pkts will be used in this case), and now my application starts
> getting packets with DPDK1.8 and the entire application usecase works fine
> (ofcourse my application had to adapt to the mbuf structure changes which I
> have done)
> 
> I am kind of coming to the conclusion that ixgbe_recv_scattered_pkts has
> something broken in DPDK1.8 as compared to the earlier versions by the
> above empirical evidence.
> 
> Has anybody else faced a similar issue ?
> 
> Regards
> -Prashant

This is worrying to hear. In 1.8, there is now the receive_scattered_pkts_vec
function which manages changed mbufs. This was tested - both in development and
in validation - before release, but since it's new code, it's entirely possible
we missed something. Can you perhaps try disabling the vector driver in 1.8,
and see if receiving scattered packets/chained mbufs works? 

Regards,
/Bruce