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

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Date:	Tue, 03 Aug 2010 17:30:44 -0700
From:	Rick Jones <rick.jones2@...com>
To:	Jack Zhang <jack.zhang2011@...il.com>
CC:	netdev@...r.kernel.org
Subject: Re: can TCP socket send buffer be over used?

Jack Zhang wrote:
> I understand that when the buffer size is set to 128 KB, I actually
> got a buffer of 256 KB as the kernel doubles the buffer size. I also
> understand that half the doubled buffer size is used for meta data
> instead of the actual data to be transferred. So basically the
> effective buffer sizes for the two examples  are just 128 KB and 512
> KB respectively.

It may not be strictly 1/2.  One way to check would be to take a tcpdump trace 
on the sending side, and either work-out manually the most the connection has 
outstanding at a time, or run the binary trace through something like tcptrace.

rick jones
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