[Fwd: TCP RTO]

George V. Neville-Neil gnn at neville-neil.com
Wed Sep 8 16:32:46 PDT 2004

At Wed, 08 Sep 2004 11:52:30 -0700,
julian wrote:
> My curiosity is if we see the tcp.cc code inside, 

tcp.cc ?  That's not a kernel file.

> there are two different version of srtt (smoothed rtt) and rttvar
> (smoothed mean deviation estimator). The one is simply 'srtt' and
> 'rttvar' and the other is 't_srtt' and 't_rttvar'. The unit of
> t_srtt is 'ticks * 8' and the unit of t_rttvar is 'ticks * 4'.

In -CURRENT, and I would suspect most recent versions of FreeBSD, the
only variables I find are t_srtt and t_rttvar which are used as fixed
point values.  srtt and rttvar were variables used in the older (BSD
4.4?) code.  I believe they were documented in Steven's TCP/IP
Illustrated Volume 2 but I don't have my copy here so I can't check.


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