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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: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
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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97
include/trace/events/tcp.h
View File

@ -1,3 +1,4 @@
/* 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 */

3
net/ipv4/tcp_input.c
View File

@ -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);