$cat /proc/sys/net/ipv4/tcp_frto_response 0 $
When F-RTO has detected that a TCP retransmission timeout was spurious (i.e, the timeout would have been avoided had TCP set a longer retransmission timeout), TCP has several options what to do next. Possible values are: 0 Rate halving based; a smooth and conservative response, results in halved cwnd and ssthresh after one RTT 1 Very conservative response; not recommended because even though being valid, it interacts poorly with the rest of Linux TCP, halves cwnd and ssthresh immediately 2 Aggressive response; undoes congestion control measures that are now known to be unnecessary (ignoring the possibility of a lost retransmission that would require TCP to be more cautious), cwnd and ssthresh are restored to the values prior timeout Default: 0 (rate halving based) source : Linux kernel source documentation.
Slow-start threshold (ssthresh) state variable is used to determine whether the slow-start or congestion avoidance algorithm is used to control data transmission. source : http://www.opalsoft.net/qos/TCP-1010.htm
qw_tools/System.map 25124: c03764a0 D sysctl_tcp_ecn 25125: c03764a4 D sysctl_tcp_frto_response 25126: c03764a8 D sysctl_tcp_nometrics_save github.com/vjosech/QemuWatcher.git - Unknown code/ns-2/?raw-diff/1056ff50e303/tcp/tcp.h 445: + /* for experimental high-speed TCP */ 446: + /* These four parameters define the HighSpeed response function. */ 447: + int low_window_; /* window for turning on high-speed TCP */ 448: + int high_window_; /* target window for new response function */ 449: + double high_p_; /* target drop rate for new response function */ yans.inria.fr/code/ns-2/?raw-diff/1056ff50e303/tcp/tcp.h - BSD - C++ -
Research Paper. http://www.jeffrin.in/wp-content/uploads/2010/06/2008_Enhanced-Response-Algorithm-for-Spurious-TCP.pdf