netdev - Re: 3.10.0 network trace

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Date:	Wed, 11 Sep 2013 09:32:04 -0700
From:	Yuchung Cheng <ycheng@...gle.com>
To:	Josh Boyer <jwboyer@...oraproject.org>
Cc:	Michael Sterrett <michael@...rretts.net>,
	netdev <netdev@...r.kernel.org>,
	Neal Cardwell <ncardwell@...gle.com>,
	Nandita Dukkipati <nanditad@...gle.com>
Subject: Re: 3.10.0 network trace

On Wed, Sep 11, 2013 at 5:49 AM, Josh Boyer <jwboyer@...oraproject.org> wrote:
> On Sun, Jul 21, 2013 at 9:36 PM, Michael Sterrett <michael@...rretts.net> wrote:
>> Since upgraded to 3.10.1 which exhibits the same issue (probably not
>> surprising).
>>
>> sysctl net.ipv4.tcp_frto=0 net.ipv4.tcp_early_retrans=3 seems to take
>> care of it.
>
> We're still getting reports of this with 3.10.10 in Fedora [1].  At
> least one of the reporters has said those sysctl settings didn't help.
>
> Is there anything else that can be gathered to help track this down?
since frto=0 didn't help, I suspect it's either a bug introduced in
the tail loss probe patch 9b717a8d (tcp: TLP loss detection) or other
changes related loss recovery.

could you try disable TLP by
sysctl net.ipv4.tcp_frto=0 net.ipv4.tcp_early_retrans=1

if it still does not work. disable any form of early retransmit by
sysctl net.ipv4.tcp_frto=0 net.ipv4.tcp_early_retrans=0

if you can test a custom build kernel, please try this debugging patch.

>
> josh
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=989251

Download attachment "0001-tcp-debug-fastretrans-warning.patch" of type "application/octet-stream" (1525 bytes)