netdev - Re: [PATCH net] r8169: fix NAPI handling under high load

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Date:   Thu, 18 Oct 2018 13:52:33 +0200
From:   Holger Hoffstätte <holger@...lied-asynchrony.com>
To:     Jonathan Woithe <jwoithe@...ad.com.au>,
        Heiner Kallweit <hkallweit1@...il.com>
Cc:     Francois Romieu <romieu@...zoreil.com>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] r8169: fix NAPI handling under high load

On 10/18/18 08:15, Jonathan Woithe wrote:
> On Thu, Oct 18, 2018 at 08:03:32AM +0200, Heiner Kallweit wrote:
>> On 18.10.2018 07:58, Jonathan Woithe wrote:
>>> On Thu, Oct 18, 2018 at 01:30:51AM +0200, Francois Romieu wrote:
>>>> Holger Hoffstätte <holger@...lied-asynchrony.com> :
>>>> [...]
>>>> The bug will induce delayed rx processing when a spike of "load" is
>>>> followed by an idle period.
>>>
>>> If this is the case, I wonder whether this bug might also be the cause of
>>> the long reception delays we've observed at times when a period of high
>>> network load is followed by almost nothing[1].  That thread[2] details the
>>> investigations subsequently done.  A git bisect showed that commit
>>> da78dbff2e05630921c551dbbc70a4b7981a8fff was the origin of the misbehaviour
>>> we were observing.
>>>
>>> We still see the problem when we test with recent kernels.  It would be
>>> great if the underlying problem has now been identified.
>>>
>>> I can possibly scrape some hardware together to test any proposed fix under
>>> our workload if there was interest.
>>>
>> Proposed fix is here:
>> https://patchwork.ozlabs.org/patch/985014/
>> Would be good if you could test it. Thanks!
> 
> I should be able to do so tomorrow.  Which kernel would you like me to apply
> the patch to?

Hi Jonathan,

I'm already running it on 4.18.15, so either that or latest 4.19-rc would
work as well.

cheers
Holger