Date:	Mon, 9 May 2016 14:37:55 -0700
From:	Tom Herbert <tom@...bertland.com>
To:	Alexander Duyck <alexander.duyck@...il.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 2:35 PM, Alexander Duyck
<alexander.duyck@...il.com> wrote:
> On Mon, May 9, 2016 at 10:32 AM, Alexander Duyck
> <alexander.duyck@...il.com> wrote:
>> 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.
>
> So I think I have figured out the MTU problem.  You need to go through
> and audit the spots where you are using GRE_ flags instead of TUNNEL_
> flags.  Specifically in ip6gre_tnl_link_config you are using GRE_
> flags to test o_flags which is configured to use the TUNNEL_ prefixed
> flags.  When I changed those out then the MTU started coming out
> correct again.  There were a couple other places you were using
> GRE_SEQ where you should have been using TUNNEL_SEQ as well so you
> could probably clean those up and add them to patch 3 of your set that
> was fixing the flags so that they should be TUNNEL_ prefixed.
>
>>>> 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.
>
> I'm still doing some digging on my end.  I'm hoping to have this
> figured out by the end of today.
>

Yes, I will be sending a patch shortly for that if you can try it.

Tom

> - Alex

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