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

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Jan 09, 2015 at 06:45:57AM +0000, Prashant Upadhyaya wrote:
> Hi Bruce,
> 
> I tried with your suggestion.
> 
> When I disable the _vec function with the following config change, the usecase works for me. So it points to some issue in the _vec function.
> 
> CONFIG_RTE_IXGBE_INC_VECTOR=y, I changed this parameter to CONFIG_RTE_IXGBE_INC_VECTOR=n
> 
> There appears to be some gottcha in the function therefore, somebody may want to run some tests again perhaps with jumbo frames enabled (and sending small normal frames)
> 
> Regards
> -Prashant
> 

Yes, we'll perform additional testing and see what we can turn up.

/Bruce

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> Sent: Thursday, January 08, 2015 7:17 PM
> To: Prashant Upadhyaya
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] Packet Rx issue with DPDK1.8
> 
> 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
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