taglinefilesource code
when46include/linux/skbuff.hvolatile unsigned long  when;  /* used to compute rtt's  */
when1824net/inet/ip.cskb->when = jiffies;
when503net/inet/skbuff.cn->when=skb->when;
when378net/inet/tcp.cskb->when = jiffies;
when2977net/inet/tcp.cm = jiffies - oskb->when;  /* RTT */
when3219net/inet/tcp.c(sk->send_head->when + sk->rto < jiffies))) 
when3221net/inet/tcp.cif(sk->send_head->when + sk->rto < jiffies)
when178net/inet/timer.cif (jiffies < skb->when + sk->rto) 
when180net/inet/timer.creset_timer (sk, TIME_WRITE, skb->when + sk->rto - jiffies);