Re: [dpdk-dev] ixgbe: ierrors counter spuriously increasing in DPDK 2.1

["Van Haaren, Harry" <harry.van.haaren@intel.com>]

> From: Martin Weiser [mailto:martin.weiser@allegro-packets.com]
> Subject: Re: [dpdk-dev] ixgbe: ierrors counter spuriously increasing in DPDK 2.1

> The
> rx-error which showed up immediately after starting the interface is
> gone since this was probably caused by mac_remote_errors. 

Improvement - that's good.

> But we still
> see a huge number of rx-errors although all packets are received
> properly and when looking at the extended stats those come from the
> rx_l3_l4_xsum_error counter.

That is useful information, good to know that statistic is the root cause.

> In our setup we are dealing with lots of UDP traffic which does have the
> UDP checksum set to 0 (which to my knowledge is allowed for UDP).

Yes indeed checksum calculation for UDP is optional, and should be set to zero when not performed.

> This
> traffic seems to cause those rx_l3_l4_xsum_errors.
> When doing the same
> test with other NICs (e.g. XL710) no rx-errors are accounted.

So this is a ixgbe bug, and listed in the errata, item 43 "Integrity Error Reported for IPv4/UDP Packets with Zero Checksum" in http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/82599-10-gbe-controller-spec-update.pdf 

> For the generic stats interface I would prefer only packets that could
> not be received to be accounted in the rx-error counter regardless of
> the actual NIC. What do you think?

Agreed. I've sent a patch that removes "xec", the register name for l3_l4_xsum_errors:
http://dpdk.org/dev/patchwork/patch/8678/

Would you test it please? -Harry