CCID 3 performance - some further thoughts

[Gerrit Renker <gerrit@erg.abdn.ac.uk>]

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