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

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Date:	Thu, 17 Mar 2016 11:27:55 -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 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/