Date:	Mon, 9 May 2016 10:32:26 -0700
From:	Alexander Duyck <alexander.duyck@...il.com>
To:	Tom Herbert <tom@...bertland.com>
Cc:	David Miller <davem@...emloft.net>,
	Netdev <netdev@...r.kernel.org>, Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v3 net-next 00/11] ipv6: Enable GUEoIPv6 and more fixes
 for v6 tunneling

On Mon, May 9, 2016 at 9:56 AM, Tom Herbert <tom@...bertland.com> wrote:
> On Fri, May 6, 2016 at 8:03 PM, Alexander Duyck
> <alexander.duyck@...il.com> wrote:
>> On Fri, May 6, 2016 at 7:11 PM, Tom Herbert <tom@...bertland.com> wrote:
>>> On Fri, May 6, 2016 at 7:03 PM, Alexander Duyck
>>> <alexander.duyck@...il.com> wrote:
>>>> On Fri, May 6, 2016 at 6:57 PM, Tom Herbert <tom@...bertland.com> wrote:
>>>>> On Fri, May 6, 2016 at 6:09 PM, Alexander Duyck
>>>>> <alexander.duyck@...il.com> wrote:
>>>>>> On Fri, May 6, 2016 at 3:11 PM, Tom Herbert <tom@...bertland.com> wrote:
>>>>>>> This patch set:
>>>>>>>   - Fixes GRE6 to process translate flags correctly from configuration
>>>>>>>   - Adds support for GSO and GRO for ip6ip6 and ip4ip6
>>>>>>>   - Add support for FOU and GUE in IPv6
>>>>>>>   - Support GRE, ip6ip6 and ip4ip6 over FOU/GUE
>>>>>>>   - Fixes ip6_input to deal with UDP encapsulations
>>>>>>>   - Some other minor fixes
>>>>>>>
>>>>>>> v2:
>>>>>>>   - Removed a check of GSO types in MPLS
>>>>>>>   - Define GSO type SKB_GSO_IPXIP6 and SKB_GSO_IPXIP4 (based on input
>>>>>>>     from Alexander)
>>>>>>>   - Don't define GSO types specifally for IP6IP6 and IP4IP6, above
>>>>>>>     fix makes that uncessary
>>>>>>>   - Don't bother clearing encapsulation flag in UDP tunnel segment
>>>>>>>     (another item suggested by Alexander).
>>>>>>>
>>>>>>> v3:
>>>>>>>   - Address some minor comments from Alexander
>>>>>>>
>>>>>>> Tested:
>>>>>>>    Tested a variety of case, but not the full matrix (which is quite
>>>>>>>    large now). Most of the obivous cases (e.g. GRE) work fine. Still
>>>>>>>    some issues probably with GSO/GRO being effective in all cases.
>>>>>>>
>>>>>>>     - IPv4/GRE/GUE/IPv6 with RCO
>>>>>>>       1 TCP_STREAM
>>>>>>>         6616 Mbps
>>>>>>>       200 TCP_RR
>>>>>>>         1244043 tps
>>>>>>>         141/243/446 90/95/99% latencies
>>>>>>>         86.61% CPU utilization
>>>>>>>     - IPv6/GRE/GUE/IPv6 with RCO
>>>>>>>       1 TCP_STREAM
>>>>>>>         6940 Mbps
>>>>>>>       200 TCP_RR
>>>>>>>         1270903 tps
>>>>>>>         138/236/440 90/95/99% latencies
>>>>>>>         87.51% CPU utilization
>>>>>>>
>>>>>>>      - IP6IP6
>>>>>>>       1 TCP_STREAM
>>>>>>>         2576 Mbps
>>>>>>>       200 TCP_RR
>>>>>>>         498981 tps
>>>>>>>         388/498/631 90/95/99% latencies
>>>>>>>         19.75% CPU utilization (1 CPU saturated)
>>>>>>>
>>>>>>>      - IP6IP6/GUE/IPv6 with RCO
>>>>>>>       1 TCP_STREAM
>>>>>>>         1854 Mbps
>>>>>>>       200 TCP_RR
>>>>>>>         1233818 tps
>>>>>>>         143/244/451 90/95/99% latencies
>>>>>>>         87.57 CPU utilization
>>>>>>>
>>>>>>>      - IP4IP6
>>>>>>>       1 TCP_STREAM
>>>>>>>       200 TCP_RR
>>>>>>>         763774 tps
>>>>>>>         250/318/466 90/95/99% latencies
>>>>>>>         35.25% CPU utilization (1 CPU saturated)
>>>>>>>
>>>>>>>      - GRE with keyid
>>>>>>>       200 TCP_RR
>>>>>>>         744173 tps
>>>>>>>         258/332/461 90/95/99% latencies
>>>>>>>         34.59% CPU utilization (1 CPU saturated)
>>>>>>
>>>>>> So I tried testing your patch set and it looks like I cannot get GRE
>>>>>> working for any netperf test.  If I pop the patches off it is even
>>>>>> worse since it looks like patch 3 fixes some tunnel flags issues, but
>>>>>> still doesn't resolve all the issues introduced with b05229f44228
>>>>>> ("gre6: Cleanup GREv6 transmit path, call common GRE functions").
>>>>>> Reverting the entire patch seems to resolve the issues, but I will try
>>>>>> to pick it apart tonight to see if I can find the other issues that
>>>>>> weren't addressed in this patch series.
>>>>>>
>>>>>
>>>>> Can you give details about configuration, test you're running, and HW?
>>>>
>>>> The issue looks like it may be specific to ip6gretap.  I'm running the
>>>> test over an i40e adapter, but it shouldn't make much difference.  I'm
>>>> thinking it may have something to do with the MTU configuration as
>>>> that is one of the things I am noticing has changed between the
>>>> working and the broken version of the code.
>>>>
>>> I'm not seeing any issue with configuring:
>>>
>>> ip link add name tun8 type ip6gretap remote
>>> 2401:db00:20:911a:face:0:27:0 local 2401:db00:20:911a:face:0:25:0 ttl
>>> 225
>>>
>>> MTU issues would not surprise me with IPv6 though. This is part of the
>>> area of code that seems drastically different than what IPv4 is doing.
>>
>> I am also using a key.
>>
>>         ip link add $name type ip6gretap key $net \
>>                 local fec0::1 remote $addr6 ttl 225 dev $PF0
>>
> I don't see any issue with key enabled.
>
>> Does the device you are using support any kind of checksum offload for
>> inner headers on GRE tunnels?  It looks like if I turn off checksums
>
> I don't believe so.
>
>> and correct the MTU I can then send traffic without issues.  I'd say
>> that the Tx cleanup probably introduced 3 regressions.  The first one
>> you addressed in patch 3 which fixes the flags.  The second being the
>> fact that the MTU is wrong, and the third being something that
>> apparently broke checksum and maybe segmentation offload for
>> ip6gretap.
>>
> The MTU can be set in place in IPv6 code that doesn't exist in Ipv4. I
> am especially wondering about the "if (p->flags & IP6_TNL_F_CAP_XMIT)"
> block.
>
>> Really I think the transmit path cleanup should have probably been
>> broken down into a set of patches rather than slamming it in all in
>> one block.  I can spend some time next week trying to sort it out if
>> you don't have any hardware that supports GRE segmentation or checksum
>> offload.  If worse comes to worse I will just try breaking the revert
>> down into a set of smaller patches so I can figure out exactly which
>> change broke things.
>>
> I am still trying to reproduce.

What NICs are you testing with?  Depending on the NIC I might be able
to point you in the direction of something that can reproduce the
issue.

At this point I am thinking it is an issue with a header offset since
I believe GSO resets all that and probably corrects the issue.

Thanks.

- Alex

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