bpftrace 跟踪 tcp_write_xmit （内核TCP写出提交）

跟踪

bpftrace -e '
kprobe:tcp_write_xmit {
  $sk = (struct sock *)arg0;
  $cwnd = ((struct tcp_sock *)$sk)->snd_cwnd;
  $rate = ((struct sock *)$sk)->sk_pacing_rate;
  if ($cwnd > 1000) {
    printf("tcp_write_xmit cwnd=%u pacing=%llu packets_out=%u\n",
      $cwnd, $rate, ((struct tcp_sock *)$sk)->packets_out);
  }
}

跟踪 delivered、snd_wnd

bpftrace -e '
kprobe:tcp_write_xmit {
  $sk = (struct sock *)arg0;
  $tp = (struct tcp_sock *)$sk;
  $cwnd = $tp->snd_cwnd;
  $rate = $sk->sk_pacing_rate;
  if ($cwnd > 5000) {
    printf("tcp_write_xmit cwnd=%u pac=%llu out=%u del=%u snd_wnd=%u\n",
      $cwnd, $rate, $tp->packets_out, $tp->delivered, $tp->snd_wnd);
  }
}'