netdev - Re: [PATCH net-next] tcp: properly send new data in fast recovery in first RTT

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Message-ID: <1371009475.3252.53.camel@edumazet-glaptop>
Date:	Tue, 11 Jun 2013 20:57:55 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Neal Cardwell <ncardwell@...gle.com>
Cc:	Yuchung Cheng <ycheng@...gle.com>,
	David Miller <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Nandita Dukkipati <nanditad@...gle.com>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: properly send new data in fast recovery
 in first RTT

On Tue, 2013-06-11 at 19:56 -0400, Neal Cardwell wrote:
> On Tue, Jun 11, 2013 at 6:35 PM, Yuchung Cheng <ycheng@...gle.com> wrote:
> > Linux sends new unset data during disorder and recovery state if all
> > (suspected) lost packets have been retransmitted ( RFC5681, section
> > 3.2 step 1 & 2, RFC3517 section 4, NexSeg() Rule 2).  One requirement
> > is to keep the receive window about twice the estimated sender's
> > congestion window (tcp_rcv_space_adjust()), assuming the fast
> > retransmits repair the losses in the next round trip.
> >
> > But currently it's not the case on the first round trip in either
> > normal or Fast Open connection, beucase the initial receive window
> > is identical to (expected) sender's initial congestion window. The
> > fix is to double it.
> >
> > Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> 
> Acked-by: Neal Cardwell <ncardwell@...gle.com>

Yes, this is indeed a very nice catch, thanks Yuchung !

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



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