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net: tcp: Add trace events for TCP congestion window tracing

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This adds an event to trace TCP stat variables with
slightly intrusive trace-event. This uses ftrace/perf
event log buffer to trace those state, no needs to
prepare own ring-buffer, nor custom user apps.

User can use ftrace to trace this event as below;

  # cd /sys/kernel/debug/tracing
  # echo 1 > events/tcp/tcp_probe/enable
  (run workloads)
  # cat trace

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Masami Hiramatsu
2017-12-29 11:45:51 +09:00
committed by David S. Miller
parent 4e3b95f198
commit c3fde1bd28
2 changed files with 100 additions and 0 deletions
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3
net/ipv4/tcp_input.c
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@@ -5299,6 +5299,9 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
unsigned int len = skb->len;
struct tcp_sock *tp = tcp_sk(sk);
/* TCP congestion window tracking */
trace_tcp_probe(sk, skb);
tcp_mstamp_refresh(tp);
if (unlikely(!sk->sk_rx_dst))
inet_csk(sk)->icsk_af_ops->sk_rx_dst_set(sk, skb);