Commit c3fde1bd authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by David S. Miller
Browse files

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



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: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4e3b95f1

include/trace/events/tcp.h

+97 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#undef TRACE_SYSTEM

#define TRACE_SYSTEM tcp
@@ -8,6 +9,7 @@ 
#include <linux/tcp.h>

#include <linux/tracepoint.h>

#include <net/ipv6.h>

#include <net/tcp.h>



#define TP_STORE_V4MAPPED(__entry, saddr, daddr)		\

	do {							\
@@ -254,6 +256,101 @@ TRACE_EVENT(tcp_retransmit_synack, 
		  __entry->saddr_v6, __entry->daddr_v6)

);





#define TP_STORE_ADDR_PORTS_V4(__entry, inet, sk)			\

	do {								\

		struct sockaddr_in *v4 = (void *)__entry->saddr;	\

									\

		v4->sin_family = AF_INET;				\

		v4->sin_port = inet->inet_sport;			\

		v4->sin_addr.s_addr = inet->inet_saddr;			\

		v4 = (void *)__entry->daddr;				\

		v4->sin_family = AF_INET;				\

		v4->sin_port = inet->inet_dport;			\

		v4->sin_addr.s_addr = inet->inet_daddr;			\

	} while (0)



#if IS_ENABLED(CONFIG_IPV6)



#define TP_STORE_ADDR_PORTS(__entry, inet, sk)				\

	do {								\

		if (sk->sk_family == AF_INET6) {			\

			struct sockaddr_in6 *v6 = (void *)__entry->saddr; \

									\

			v6->sin6_family = AF_INET6;			\

			v6->sin6_port = inet->inet_sport;		\

			v6->sin6_addr = inet6_sk(sk)->saddr;		\

			v6 = (void *)__entry->daddr;			\

			v6->sin6_family = AF_INET6;			\

			v6->sin6_port = inet->inet_dport;		\

			v6->sin6_addr = sk->sk_v6_daddr;		\

		} else							\

			TP_STORE_ADDR_PORTS_V4(__entry, inet, sk);	\

	} while (0)



#else



#define TP_STORE_ADDR_PORTS(__entry, inet, sk)		\

	TP_STORE_ADDR_PORTS_V4(__entry, inet, sk);



#endif



TRACE_EVENT(tcp_probe,



	TP_PROTO(struct sock *sk, struct sk_buff *skb),



	TP_ARGS(sk, skb),



	TP_STRUCT__entry(

		/* sockaddr_in6 is always bigger than sockaddr_in */

		__array(__u8, saddr, sizeof(struct sockaddr_in6))

		__array(__u8, daddr, sizeof(struct sockaddr_in6))

		__field(__u16, sport)

		__field(__u16, dport)

		__field(__u32, mark)

		__field(__u16, length)

		__field(__u32, snd_nxt)

		__field(__u32, snd_una)

		__field(__u32, snd_cwnd)

		__field(__u32, ssthresh)

		__field(__u32, snd_wnd)

		__field(__u32, srtt)

		__field(__u32, rcv_wnd)

	),



	TP_fast_assign(

		const struct tcp_sock *tp = tcp_sk(sk);

		const struct inet_sock *inet = inet_sk(sk);



		memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));

		memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));



		TP_STORE_ADDR_PORTS(__entry, inet, sk);



		/* For filtering use */

		__entry->sport = ntohs(inet->inet_sport);

		__entry->dport = ntohs(inet->inet_dport);

		__entry->mark = skb->mark;



		__entry->length = skb->len;

		__entry->snd_nxt = tp->snd_nxt;

		__entry->snd_una = tp->snd_una;

		__entry->snd_cwnd = tp->snd_cwnd;

		__entry->snd_wnd = tp->snd_wnd;

		__entry->rcv_wnd = tp->rcv_wnd;

		__entry->ssthresh = tcp_current_ssthresh(sk);

		__entry->srtt = tp->srtt_us >> 3;

	),



	TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x "

		  "snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u "

		  "rcv_wnd=%u",

		  __entry->saddr, __entry->daddr, __entry->mark,

		  __entry->length, __entry->snd_nxt, __entry->snd_una,

		  __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,

		  __entry->srtt, __entry->rcv_wnd)

);



#endif /* _TRACE_TCP_H */



/* This part must be outside protection */

net/ipv4/tcp_input.c

+3 −0
Original line number Diff line number Diff line
@@ -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);

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