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From: David Miller <davem@davemloft.net>
To: damian@tvk.rwth-aachen.de
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH 0/3][v2] tcp: fix ICMP-RTO war
Date: Sun, 31 Jan 2010 23:33:38 -0800 (PST)	[thread overview]
Message-ID: <20100131.233338.254690877.davem@davemloft.net> (raw)
In-Reply-To: <4B635E17.406@tvk.rwth-aachen.de>

From: Damian Lukowski <damian@tvk.rwth-aachen.de>
Date: Fri, 29 Jan 2010 23:15:51 +0100

> This patches fix the current RTO calculation routine, when
> srtt and rttvar are zero, yielding an RTO of zero 
> Under some circumstances, TCPs srtt and rttvar are zero,
> yielding a calculated RTO of zero.
> This is particularly unfortunate for ICMP based RTO recalculation
> as introduced in f1ecd5d9e736660 (Revert Backoff [v3]: Revert RTO
> on ICMP destination unreachable), as it results in RTO retransmission
> flooding.
> 
> Thanks to Ilpo Jarvinen for providing debug patches and to
> Denys Fedoryshchenko for reporting and testing.
> 
> Signed-off-by: Damian Lukowski <damian@tvk.rwth-aachen.de>

I still haven't seen a detailed enough analysis of why these
tiny RTOs can come to exist in the first place.

Please show me a list of events, function by function, the value of
relevant variables and per-socket TCP state, in the TCP stack, that
show how this ends up happening.

Thanks for all of your work on this so far.

  reply	other threads:[~2010-02-01  7:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-29 22:15 [PATCH 0/3][v2] tcp: fix ICMP-RTO war Damian Lukowski
2010-02-01  7:33 ` David Miller [this message]
2010-02-08 12:34   ` Damian Lukowski
2010-02-08 21:58     ` Damian Lukowski
2010-02-09 12:37       ` Ilpo Järvinen
2010-02-09 22:29         ` Damian Lukowski

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