netdev - Re: Extreme slowness in IPIP tunnel when routing through kernel 3.18 and later

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Date:	Thu, 17 Mar 2016 14:18:17 -0700
From:	Jesse Gross <jesse@...nel.org>
To:	Patrick Boutilier <boutilpj@...et.ns.ca>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: Extreme slowness in IPIP tunnel when routing through kernel 3.18
 and later

On Thu, Mar 17, 2016 at 2:13 PM, Patrick Boutilier <boutilpj@...et.ns.ca> wrote:
> On 03/17/2016 03:27 PM, Jesse Gross wrote:
>>
>> On Thu, Mar 17, 2016 at 7:02 AM, Patrick Boutilier <boutilpj@...et.ns.ca>
>> wrote:
>>>
>>> I have an IPIP tunnel setup between two hosts in different buildings. The
>>> Linux router they route through causes extreme slowness in the tunnel
>>> when
>>> running kernels from 3.18 on . tcpdump shows many cksum errors which
>>> don't
>>> show up in the 3.17 and earlier kernels. Speed goes back to normal when
>>> rx-checksumming and tx-checksumming are turned off using ethtool on the
>>> Linux router . Would this be an effect of bulk network packet
>>> transmission
>>> that was introduced in 3.18 or some other issue?
>>
>>
>> I just sent out a likely fix, would you mind testing it?
>> https://patchwork.ozlabs.org/patch/599213/
>>
>
> Yes, that patch fixes the problem.

Great, thanks a lot for testing.