Bad interaction between 82599 hardware RSC and VLANs

[Jack Vogel]

Hey Andrew,

Not heard of this before, but I'll check around.

Jack


On Fri, Jan 13, 2012 at 3:01 PM, Andrew Boyer <aboyer at averesystems.com>wrote:

> Hello Jack,
> I'm seeing an issue on 82599 controllers.  When hardware RSC is used,
> large VLAN packets arrive without the VP bit set, even though the vtag in
> the descriptor is correct.  It totally kills the receive performance.
>  Turning off hardware RSC in the driver (falling back to software LRO)
> works fine, as does turning off LRO entirely.
>
> I've worked around the problem for now by overriding the VP bit if
> ixgbe_rxeof() finds a valid vtag in the descriptor.
>
> Have you seen this before?
>
> It's not in the latest errata.  It almost seems to be the opposite of what
> Ryan reported in November 2010 ("82599 receiving packets with vlan tag=0
> (vlan strip problem)?").
>
> Thanks,
>  Andrew
>
> --------------------------------------------------
> Andrew Boyer    aboyer at averesystems.com
>
>
>
>
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