netdev - RE: [RFC PATCH 3/5] bnx2x: Add support for segmentation of tunnels with outer checksums

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Date:   Thu, 25 Aug 2016 05:06:58 +0000
From:   Yuval Mintz <Yuval.Mintz@...gic.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
CC:     netdev <netdev@...r.kernel.org>
Subject: RE: [RFC PATCH 3/5] bnx2x: Add support for segmentation of tunnels
 with outer checksums

> >> This patch assumes that the bnx2x hardware will ignore existing
> >> IPv4/v6 header fields for length and checksum as well as the length
> >> and checksum fields for outer UDP and GRE headers.
> >>
> >> I have no means of testing this as I do not have any bnx2x hardware
> >> but thought I would submit it as an RFC to see if anyone out there
> >> wants to test this and see if this does in fact enable this
> >> functionality allowing us to to segment tunneled frames that have an outer
> checksum.
> >>
> >> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
> >
> > So it took me some [well, a lot] time to reach this, but I've finally  gave it a try.
> > I saw a performance boost with the partial support - Throughput for
> > vxlan tunnels with and without udpcsum were almost identical after
> > this, whereas without this patch the udpcsum prevented GSO and a
> > TCP/IPv4 connection on top of it got roughly half the throughput.
> >
> > However, I did encounter one oddity I couldn't explain - After I've
> > disabled tx-udp_tnl-segmentation via ethtool on the base interface,
> > got left with:
> >    tx-gso-partial: on
> >    tx-udp_tnl-segmentation: off
> >    tx-udp_tnl-csum-segmentation: on
> >
> > When I ran traffic over both vxlan tunnels the one with the udpcsum
> > was still Passing gso aggregations to base device to transmit [and the
> > throughput was same as before], where's the tunnel without the udpcsum
> > showed only MTU-sized packets reaching the base interface for
> > transmission [which is what I've expected]
> >
> > Any idea why that happened?
> 
> So the way they are implemented tx-udp_tnl-segmentation and tx-udp_tnl-
> csum-segmentation are treated as two separate features.
> The kernel currently gives them the same treatment as NETIF_F_TSO and
> NETIF_F_TSO6.  You can disable one and the other still functions.
> 
> Now if you disable tx-gso-partial you should expect to see tx-udp_tnl-csum-
> segmentation be disabled because it is dependent on the partial GSO offload.
> 
> - Alex

O.k., thanks.
Then I'll run some more testing scenarios, and assuming everything works
fine I'll re-send this. Alex - should I place you at the 'from' field?