taglinefilesource code
ssthresh222include/net/sock.hvolatile unsigned short  ssthresh;
ssthresh407net/ipv4/tcp_input.cnewsk->ssthresh = 0;
ssthresh689net/ipv4/tcp_input.cif (sk->cong_window < sk->ssthresh)  
ssthresh96net/ipv4/tcp_timer.csk->ssthresh = sk->cong_window >> 1; /* remember window where we lost */