netdev - Re: [PATCH v3 net-next 00/11] ipv6: Enable GUEoIPv6 and more fixes for v6 tunneling

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Date:	Fri, 6 May 2016 20:03:02 -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 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

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
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.

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.

- Alex