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From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
To: dccp@vger.kernel.org
Subject: CCID 3 performance - some further thoughts
Date: Tue, 05 Dec 2006 20:19:32 +0000	[thread overview]
Message-ID: <200612052019.32837@strip-the-willow> (raw)

I have been experimenting with CCID 3 on various computers,
below is a list of observations:

 * I didn't use netem or anything (no loss), yet the receiver reported loss
   
 * I quite frequently got those messages from tfrc_calc_x, like

   tfrc_calc_x: Value of p (29) below resolution. Substituting 100

   This should not happen - I believe that these p measurements are bogus
   and we should check if the loss rate computation is ok.

 * the behaviour of iperf is very unpredictable, sometimes it seems that
   throughput is directly related to current system load

 * the RTT values are almost always higher than the RTT computed by ICMP
   ping - highly desirable to find ways of obtaining sharper estimates

 * would it make sense to define an RTT cut-off value, such as e.g. 2MSL
   (120 seconds) and regard all RTT estimates above this value as nonsensical?
   E.g.: #define DCCP_SENSIBLE_RTT_VALUE_MAX 120 * USEC_PER_SEC

- Gerrit

             reply	other threads:[~2006-12-05 20:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-05 20:19 Gerrit Renker [this message]
2006-12-05 20:39 ` CCID 3 performance - some further thoughts Ian McDonald
2006-12-05 21:26 ` Gerrit Renker
2006-12-05 21:38 ` Ian McDonald

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