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Date:      Fri, 13 Jan 2012 18:01:51 -0500
From:      Andrew Boyer <aboyer@averesystems.com>
To:        Jack Vogel <jack.vogel@intel.com>
Cc:        freebsd-net@freebsd.org, Ryan Stone <rysto32@gmail.com>
Subject:   Bad interaction between 82599 hardware RSC and VLANs
Message-ID:  <10A2858D-8DA8-45C4-B9A6-00CFA172404F@averesystems.com>

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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=3D0 (vlan strip problem)?").

Thanks,
  Andrew

--------------------------------------------------
Andrew Boyer	aboyer@averesystems.com







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