netdev - Re: No GSOs to i40e with VXLAN

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Date:	Sat, 14 Jun 2014 17:04:31 -0700 (PDT)
From:	Joseph Gasparakis <joseph.gasparakis@...el.com>
To:	Tom Herbert <therbert@...gle.com>
cc:	Joseph Gasparakis <joseph.gasparakis@...el.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>
Subject: Re: No GSOs to i40e with VXLAN



On Sat, 14 Jun 2014, Tom Herbert wrote:

> I was able to debug the issue (thanks for lending me the machines with
> i40 Eric!). Problem is that SKB_GSO_* bits are out of sync with the
> corresponding NETIF flags. I post a fix today along with adding the
> BUILD_BUG_ONs in net_gso_ok that are intended to detect this.
>

Thanks for this Tom. Looking forward to your patch.
 
> Thanks,
> Tom
> 
> On Fri, Jun 13, 2014 at 9:38 PM, Joseph Gasparakis
> <joseph.gasparakis@...el.com> wrote:
> >
> >
> > On Fri, 13 Jun 2014, Tom Herbert wrote:
> >
> >> On Fri, Jun 13, 2014 at 5:15 PM, Joseph Gasparakis
> >> <joseph.gasparakis@...el.com> wrote:
> >> > Hi all,
> >> >
> >> > I quickly tested VXLAN on i40e with net-next with commit id
> >> > f9da455b93f6ba076935b4ef4589f61e529ae046 and the i40e driver has stopped
> >> > receiving GSOs even when advertising tx-udp_tnl-segmentation which means
> >> > our VXLAN segmentation offload. I am guessing this has something to do
> >> > with Tom's recent UDP work but this is just a guess as unfortunatly I
> >> > do not have the time to debug this, but I am signing up to review and test
> >> > patches fixing this issue.
> >> >
> >> I verified tunnel offload works properly with bnx2x (I'm using simple
> >> vxlan interfaces not OVS).
> >>
> >
> > Ok, I will try to have a quick look at bnx2x and i40e and see the
> > differences in what the two drivers advertise in terms of netdev features and
> > hw_enc_features.
> >
> >> One possibility I can think of is that UDP checksums are somehow
> >> enabled. If you're using IPv6 this probably the case (but I assume
> >> you're seeing this with IPv4). If checksums are inadvertently enabled
> >> somehow in IPv4 this should should up in tcpdump on the Ethernet
> >> interface.
> >
> > Let me explain a bit my setup:
> >
> > I am using two linux boxes back to back, on my DUT I have an i40e and I
> > am bringing a vxlan interface in both machines. No bridge, no VMs, no OVS.
> >
> > I am using some simple perl scripts using TCP sockets to send a number of
> > bytes from DUT to my link partner and even if I send 50k in one message I
> > don't see any GSOs. Instead I get many non-GSO skbs leading me to the
> > conclusion that the stack must have segmented the skb before passing it on
> > to the driver. I am also using netperf with TCP_STREAM and I don't see any
> > GSOs either. All the above done using IPv4 only. And if I do the same on
> > the i40e interface instead of vxlan I do see GSOs again.
> >
> > Both these tests would result to the stack sending GSOs last time I did a
> > smoke test on vxlan and i40e (about 3 weeks ago or so...).
> >
> > The checksum offloads seem to be working as before however.
> >
> > Thanks
> >
> > Joseph
> >
> >>
> >> Thanks,
> >> Tom
> >>
> >> > The driver still gets GSOs with non VXLAN traffic (tested with TCP).
> >> >
> >> > Thanks
> >> >
> >> > Joseph
> >>
> 
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