probe kernel.statement("tcp_ack@./net/ipv4/tcp_input.c:3751")
{
  if ($sk->sk_send_head != NULL) {
	  ack_seq = @cast(&$skb->cb[0], "tcp_skb_cb", "kernel<net/tcp.h>")->seq
	  printf("ack: %d, ack_seq: %d, prior_snd_una: %d\n", $ack, ack_seq, $prior_snd_una)
	  seq = @cast(&$sk->sk_send_head->cb[0], "tcp_skb_cb", "kernel<net/tcp.h>")->seq
	  end_seq = @cast(&$sk->sk_send_head->cb[0], "tcp_skb_cb", "kernel<net/tcp.h>")->end_seq
	  printf("sk_send_head seq:%d, end_seq: %d\n", seq, end_seq)

	  snd_wnd = @cast($sk, "tcp_sock", "kernel<linux/tcp.h>")->snd_wnd
	  snd_wl1 = @cast($sk, "tcp_sock", "kernel<linux/tcp.h>")->snd_wl1
	  ts_recent = @cast($sk, "tcp_sock", "kernel<linux/tcp.h>")->rx_opt->ts_recent
	  rcv_tsval = @cast($sk, "tcp_sock", "kernel<linux/tcp.h>")->rx_opt->rcv_tsval
	  printf("snd_wnd: %d, tcp_wnd_end: %d, snd_wl1: %d\n", snd_wnd, $prior_snd_una + snd_wnd, snd_wl1)
	  printf("flag: %x, may update window: %d\n", $flag, $flag & 0x02)
	  printf("rcv_tsval: %d, ts_recent: %d\n", rcv_tsval, ts_recent)
	  print("\n")
     }
}