From: Rick Jones <rick.jones2@hp.com>
To: Saku Ytti <saku@ytti.fi>
Cc: netdev@vger.kernel.org
Subject: Re: TCP and reordering
Date: Wed, 28 Nov 2012 10:24:12 -0800 [thread overview]
Message-ID: <50B656CC.1040001@hp.com> (raw)
In-Reply-To: <20121128085404.GB26010@pob.ytti.fi>
On 11/28/2012 12:54 AM, Saku Ytti wrote:
> On (2012-11-28 00:35 -0800), Vijay Subramanian wrote:
>
>> Also note that reordering is tracked on the sender side using the
>> per flow variable tp->reordering . This measures the amount of
>> reordering on the connection so that fast retransmit and other loss
>> recovery mechanisms are not entered prematurely. Doesn't this
>> behavior at the sender already provide the behavior you seek?
>
> Sorry I don't seem to understand what you mean. Do you mind explaining how
> the sender can help to restore performance on reordering network?
tp->reordering is initialized via the sysctl net.ipv4.tcp_reordering
which controls how anxious TCP will be to fast retransmit.
By increasing net.ipv4.tcp_reordering you make the sending TCP less
"sensitive" to duplicate ACKs and so less sensitive to reordering
detected by the receiver. The receiver is generating as many
(duplicate) ACKs as before, it is just that the sender is ignoring them
a bit more.
next prev parent reply other threads:[~2012-11-28 18:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-27 9:32 TCP and reordering Saku Ytti
2012-11-27 17:05 ` Rick Jones
2012-11-27 17:15 ` Saku Ytti
2012-11-27 18:00 ` Rick Jones
2012-11-28 2:06 ` David Miller
2012-11-28 7:26 ` Saku Ytti
2012-11-28 8:35 ` Vijay Subramanian
2012-11-28 8:54 ` Saku Ytti
2012-11-28 18:24 ` Rick Jones [this message]
2012-11-28 18:33 ` Eric Dumazet
2012-11-28 18:52 ` Vijay Subramanian
2012-11-28 18:44 ` Saku Ytti
2012-11-28 7:59 ` David Woodhouse
2012-11-28 8:21 ` Christoph Paasch
2012-11-28 8:22 ` Vijay Subramanian
2012-11-28 9:08 ` David Woodhouse
2012-11-28 11:02 ` Eric Dumazet
2012-11-28 11:49 ` David Woodhouse
2012-11-28 12:26 ` Eric Dumazet
2012-11-28 12:39 ` David Woodhouse
2012-11-28 12:52 ` Eric Dumazet
2012-11-28 15:47 ` David Woodhouse
2012-11-28 16:09 ` Eric Dumazet
2012-11-28 16:21 ` David Woodhouse
2012-11-28 16:19 ` Benjamin LaHaise
2012-11-28 16:41 ` David Woodhouse
2012-11-28 17:08 ` Benjamin LaHaise
2012-11-28 17:16 ` Eric Dumazet
2012-11-28 18:01 ` David Woodhouse
2012-11-29 15:10 ` Noel Grandin
2012-12-02 1:30 ` David Woodhouse
2012-12-02 2:40 ` Eric Dumazet
2012-12-02 9:31 ` David Woodhouse
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