netdev - Re: [ISSUE][4.20.6] mlx5 and checksum failures

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Date:   Wed, 6 Feb 2019 17:00:57 -0800
From:   Saeed Mahameed <saeedm@....mellanox.co.il>
To:     Ian Kumlien <ian.kumlien@...il.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        David Miller <davem@...emloft.net>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [ISSUE][4.20.6] mlx5 and checksum failures

On Wed, Feb 6, 2019 at 3:00 PM Ian Kumlien <ian.kumlien@...il.com> wrote:
>
> On Wed, Feb 6, 2019 at 11:49 PM Cong Wang <xiyou.wangcong@...il.com> wrote:
> >
> > On Wed, Feb 6, 2019 at 2:41 PM Ian Kumlien <ian.kumlien@...il.com> wrote:
> > >
> > > On Wed, Feb 6, 2019 at 11:38 PM Cong Wang <xiyou.wangcong@...il.com> wrote:
> > > > On Wed, Feb 6, 2019 at 2:15 PM Ian Kumlien <ian.kumlien@...il.com> wrote:
> > > > > Could we please schedule this for 4.19 and 4.20 - it's kinda breaking things
> > > >
> > > > It doesn't break anything, packets are _not_ dropped, only that the
> > > > warning itself is noisy.
> > >
> > > Not my experience, to me it slows the machine down and looses packets,
> > > I don't however know
> > > if this is the only culprit
> >
> > The packet process could be slow down because of printing
> > out this kernel warning. Packet should be still delivered to upper
> > stack, at least I didn't see any packet drops because of this.
>
> I have several machines pushing the same errors currently, while on this
> one I was logged in on the serial console and not over ssh like the others.
>
> On the other machines, typing is slow, looses characters and drops the
> connection
>
> But, again, I don't know if this is the only culprit, it sure does
> fill dmesg though =)
> (which suddenly takes minutes to show over a 100gig connection)
>
> > > You can actually see it on ping where it start out with 0.0xyx and
> > > ends up at ~10ms
> >
> > I don't understand how it could affect ICMP, it is purely TCP
> > from my point of view, even the stack trace from you says so. ;)
>
> It changes directly after the first hw checksum failure, I don't know why =/

weird, Maybe a real check-summing issue/corruption on the PCI ?!

can you try turning off checksum offloads
ethtool -K ethX  rx off