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From: Cong Wang <amwang@redhat.com>
To: Pravin Shelar <pshelar@nicira.com>
Cc: netdev <netdev@vger.kernel.org>
Subject: Re: A performance regression of gretap
Date: Thu, 11 Jul 2013 10:31:59 +0800	[thread overview]
Message-ID: <1373509919.12250.6.camel@cr0> (raw)
In-Reply-To: <CALnjE+oNMcXORdMgzHtomdf+EDknZaCsiB-+aevMbg-rsxbpww@mail.gmail.com>

On Wed, 2013-07-10 at 19:28 -0700, Pravin Shelar wrote:
> On Wed, Jul 10, 2013 at 7:15 PM, Cong Wang <amwang@redhat.com> wrote:
> > On Wed, 2013-07-10 at 06:01 -0400, Cong Wang wrote:
> >>
> >> Could you please take a look? And, gre tunnel is fine, this
> >> problem only exists for gretap. I reviewed the gretap code,
> >> but can't find any bug.
> >
> > After digging it a little bit, I found some of the packets on RX side
> > have incorrect TCP checksum after going through gretap, while the
> > packets captured on eth0 are all correct.
> >
> > Thanks.
> >
> I do not see it on my end.
> Can you tell me NIC type and features set for eth device?

Sure, it is virtio_net which is not able to do rx checksum, therefore
->ip_summed is CHECKSUM_NONE.

# ethtool -i eth0
driver: virtio_net
version: 1.0.0
firmware-version: 
bus-info: 0000:00:08.0
supports-statistics: no
supports-test: no
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: no

# ethtool -k eth0
Offload parameters for eth0:
rx-checksumming: off
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: on
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: off
rx-vlan-offload: off
tx-vlan-offload: off
ntuple-filters: off
receive-hashing: off

  reply	other threads:[~2013-07-11  2:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1025834928.1488534.1373450176613.JavaMail.root@redhat.com>
2013-07-10 10:01 ` A performance regression of gretap Cong Wang
2013-07-10 15:18   ` Rick Jones
2013-07-11  2:15   ` Cong Wang
2013-07-11  2:28     ` Pravin Shelar
2013-07-11  2:31       ` Cong Wang [this message]
2013-07-11  7:47         ` Pravin Shelar

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