netdev - Re: Recurring trace from tcp

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Message-Id: <904FADEB-C1EB-4384-BA47-0EB0273AFB71@fastly.com>
Date:	Sat, 30 May 2015 11:52:55 -0700
From:	Grant Zhang <gzhang@...tly.com>
To:	Neal Cardwell <ncardwell@...gle.com>
Cc:	Netdev <netdev@...r.kernel.org>, Yuchung Cheng <ycheng@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: Recurring trace from tcp_fragment()

Thank you Neal. Most likely I will test the patch on Monday and report
back the result.

As for the TcpExtTCPSACKReneging counter, attached is the captured
counter value on a 1-second interval for 10 minutes.

Thanks,

Grant



Download attachment "reneg.log" of type "application/octet-stream" (33055 bytes)





> On May 30, 2015, at 10:29 AM, Neal Cardwell <ncardwell@...gle.com> wrote:
> 
> On Fri, May 29, 2015 at 3:53 PM, Grant Zhang <gzhang@...tly.com> wrote:
>> Hi Neal,
>> 
>> I will be more happy to test the patch. Please send it my way.
> 
> Great. Thank you so much for being willing to do this. Attached is a
> patch for testing. I generated it and tested it relative to Linux
> v3.14.39, since your stack trace seemed to suggest that you were
> seeing this on some variant of v3.14.39. (Newer kernels would need a
> slightly different patch, since the reneging code path has changed a
> little since 3.14.)
> 
> Can you please try it out and see if it makes that warning go away?
> 
> Also, I would be interested in seeing the value of your
> TcpExtTCPSACKReneging counter, and some sense of how fast that value
> is increasing, on a machine that's seeing this issue:
>  nstat -z -a | grep Reneg
> 
> Thanks!
> 
> neal
> <0001-RFC-for-tests-on-v3.14.39-tcp-resegment-skbs-that-we.patch>