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Message-Id: <20231204114322.9218-1-lulie@linux.alibaba.com>
Date: Mon, 4 Dec 2023 19:43:22 +0800
From: Philo Lu <lulie@...ux.alibaba.com>
To: netdev@...r.kernel.org
Cc: edumazet@...gle.com,
rostedt@...dmis.org,
mhiramat@...nel.org,
mathieu.desnoyers@...icios.com,
davem@...emloft.net,
dsahern@...nel.org,
kuba@...nel.org,
pabeni@...hat.com,
martin.lau@...ux.dev,
linux-trace-kernel@...r.kernel.org,
bpf@...r.kernel.org,
xuanzhuo@...ux.alibaba.com,
dust.li@...ux.alibaba.com,
alibuda@...ux.alibaba.com,
guwen@...ux.alibaba.com,
hengqi@...ux.alibaba.com
Subject: [PATCH net-next] tcp: add tracepoints for data send/recv/acked
Add 3 tracepoints, namely tcp_data_send/tcp_data_recv/tcp_data_acked,
which will be called every time a tcp data packet is sent, received, and
acked.
tcp_data_send: called after a data packet is sent.
tcp_data_recv: called after a data packet is receviced.
tcp_data_acked: called after a valid ack packet is processed (some sent
data are ackknowledged).
We use these callbacks for fine-grained tcp monitoring, which collects
and analyses every tcp request/response event information. The whole
system has been described in SIGMOD'18 (see
https://dl.acm.org/doi/pdf/10.1145/3183713.3190659 for details). To
achieve this with bpf, we require hooks for data events that call bpf
prog (1) when any data packet is sent/received/acked, and (2) after
critical tcp state variables have been updated (e.g., snd_una, snd_nxt,
rcv_nxt). However, existing bpf hooks cannot meet our requirements.
Besides, these tracepoints help to debug tcp when data send/recv/acked.
Though kretprobe/fexit can also be used to collect these information,
they will not work if the kernel functions get inlined. Considering the
stability, we prefer tracepoint as the solution.
Signed-off-by: Philo Lu <lulie@...ux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
include/trace/events/tcp.h | 21 +++++++++++++++++++++
net/ipv4/tcp_input.c | 4 ++++
net/ipv4/tcp_output.c | 2 ++
3 files changed, 27 insertions(+)
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 7b1ddffa3dfc..1423f7cb73f9 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -113,6 +113,13 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_send_reset,
TP_ARGS(sk, skb)
);
+DEFINE_EVENT(tcp_event_sk_skb, tcp_data_recv,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+
+ TP_ARGS(sk, skb)
+);
+
/*
* tcp event with arguments sk
*
@@ -187,6 +194,20 @@ DEFINE_EVENT(tcp_event_sk, tcp_rcv_space_adjust,
TP_ARGS(sk)
);
+DEFINE_EVENT(tcp_event_sk, tcp_data_send,
+
+ TP_PROTO(struct sock *sk),
+
+ TP_ARGS(sk)
+);
+
+DEFINE_EVENT(tcp_event_sk, tcp_data_acked,
+
+ TP_PROTO(struct sock *sk),
+
+ TP_ARGS(sk)
+);
+
TRACE_EVENT(tcp_retransmit_synack,
TP_PROTO(const struct sock *sk, const struct request_sock *req),
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index bcb55d98004c..edb1e24a3423 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -824,6 +824,8 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
now = tcp_jiffies32;
+ trace_tcp_data_recv(sk, skb);
+
if (!icsk->icsk_ack.ato) {
/* The _first_ data packet received, initialize
* delayed ACK engine.
@@ -3486,6 +3488,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, const struct sk_buff *ack_skb,
}
}
#endif
+
+ trace_tcp_data_acked(sk);
return flag;
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index eb13a55d660c..cb6f2af55ce2 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2821,6 +2821,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
/* Send one loss probe per tail loss episode. */
if (push_one != 2)
tcp_schedule_loss_probe(sk, false);
+
+ trace_tcp_data_send(sk);
return false;
}
return !tp->packets_out && !tcp_write_queue_empty(sk);
--
2.32.0.3.g01195cf9f
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