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Date: Tue, 26 Mar 2013 21:02:16 +0100
From: Hagen Paul Pfeifer <hagen@jauu.net>
To: "Scheffenegger, Richard" <rs@netapp.com>
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Cc: bloat <bloat@lists.bufferbloat.net>, "aqm@ietf.org" <aqm@ietf.org>,
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Subject: Re: [Bloat] [tsvwg] [aqm] how much of a problem is buffer bloat
 today?
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* Scheffenegger, Richard | 2013-03-26 17:49:49 [+0000]:

>TCP measures RTT; 
>
>one could create a global histogram of all measured RTTs by TCP (whenever a
>valid measurement is taken), and export that with "netstat -sp tcp"... Of
>course, vastly different paths would be gobbled up together, but when
>investigating specific paths, that should be good enough as a high level
>starting point.

For Linux tcp-probe[1] is your friend. The last colum is the smoothed round trip
time. The port filter is optional and can be 0 to disable filtering. Not sure
if Linux Distribution ship this module by default. But via tcp-probe you get
accurate per-path rtt statistics without any effort (just a few CPU cycles).


Hagen

[1] http://www.linuxfoundation.org/collaborate/workgroups/networking/tcpprobe