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

[Prashant Upadhyaya <prashant.upadhyaya@aricent.com>]

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

-----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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