netdev - Re: [PATCH v3 6/7] net-tcp: Fast Open client

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Date:	Thu, 19 Jul 2012 20:00:33 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Yuchung Cheng <ycheng@...gle.com>
Cc:	davem@...emloft.net, hkchu@...gle.com, edumazet@...gle.com,
	ncardwell@...gle.com, sivasankar@...ucsd.edu,
	netdev@...r.kernel.org
Subject: Re: [PATCH v3 6/7] net-tcp: Fast Open client - detecting SYN-data
 drops

On Thu, 2012-07-19 at 09:43 -0700, Yuchung Cheng wrote:
> On paths with firewalls dropping SYN with data or experimental TCP options,
> Fast Open connections will have experience SYN timeout and bad performance.
> The solution is to track such incidents in the cookie cache and disables
> Fast Open temporarily.
> 
> Since only the original SYN includes data and/or Fast Open option, the
> SYN-ACK has some tell-tale sign (tcp_rcv_fastopen_synack()) to detect
> such drops. If a path has recurring Fast Open SYN drops, Fast Open is
> disabled for 2^(recurring_losses) minutes starting from four minutes up to
> roughly one and half day. sendmsg with MSG_FASTOPEN flag will succeed but
> it behaves as connect() then write().
> 
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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