netdev - Re: can TCP socket send buffer be over used?

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Date:	Wed, 4 Aug 2010 02:03:45 -0600
From:	Jack Zhang <jack.zhang2011@...il.com>
To:	Mikael Abrahamsson <swmike@....pp.se>
Cc:	netdev@...r.kernel.org
Subject: Re: can TCP socket send buffer be over used?

Hi Mikael,

Thanks for your reply. I'll definitely try that.

Quick question though... the link I use in my test does not have any
packet loss (it's a straight through cable between two PCs)... in this
case, would TCP congestion window size affect the result at all?

Thanks,
Jack

On 4 August 2010 01:33, Mikael Abrahamsson <swmike@....pp.se> wrote:
> On Tue, 3 Aug 2010, Jack Zhang wrote:
>
>> For example, when I set the send buffer size to 128 KB, i could get a
>> throughput up to 43 Mbps, which seems to be impossible as the (buffer
>> size) / RTT is only 10 Mbps.
>
> Are you sure the buffer actually corresponds to the congestion window TCP
> uses? I think you should use wireshark to dump the traffic and look in the
> TCP headers of the packets to see what is actually going on on the wire.
>
> --
> Mikael Abrahamsson    email: swmike@....pp.se
>
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