netdev - puzzled of the congestion control window of Scalable TCP

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Message-ID: <28850421.post@talk.nabble.com>
Date:	Thu, 10 Jun 2010 18:20:21 -0700 (PDT)
From:	jellyaaa <wgdaaa@....com>
To:	netdev@...r.kernel.org
Subject: puzzled of the congestion control window of Scalable TCP


I am now doing something related to the STCP (Scalable TCP). By printking the
dynamic snd_cwnd in linux (kernel 2.6.18) ,the result puzzled me . In
theory, if any congestion occurs, the snd_ssthresh = snd_cwnd = snd_cwnd *
0.875,but I haven't got the result I expected. The snd_cwnd changes like
this :

snd_cwnd = 1 , snd_ssthresh = 2147483647
snd_cwnd = 2 , snd_ssthresh = 2147483647
snd_cwnd = 3, snd_ssthresh = 2147483647
......
snd_cwnd = 19022, snd_ssthresh = 2147483647      // keeping this value for
several ms 
snd_cwnd = 1769, snd_ssthresh = 16645        // congestion occurs 
snd_cwnd = 1770, snd_ssthresh = 16645                  
......


>From the above data. when congestion occurs , snd_ssthresh = 16645 ~=~
19022*0.875=16626 corresponds  to the theory calculated result. no problems. 
But what is the mean of snd_cwnd = 1770? how this value is calculated .who
(where )calculated it ?


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