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| author |   Breno Leitao <leitao@debian.org> | 2025-02-14 09:07:11 -0800 |
|---|---|---|
| committer |   Paolo Abeni <pabeni@redhat.com> | 2025-02-18 15:29:53 +0100 |
| commit | 8e677a466145174e6899ceaf189e7cb7fbd6ad3f (patch) | |
| tree | 3e962e015efdd99b8550e4ec41790b76f1f1bc9d | |
| parent | Merge branch 'net-phy-marvell-88q2xxx-cleanup' (diff) | |
| download | wireguard-linux-8e677a466145174e6899ceaf189e7cb7fbd6ad3f.tar.xz wireguard-linux-8e677a466145174e6899ceaf189e7cb7fbd6ad3f.zip | |
trace: tcp: Add tracepoint for tcp_cwnd_reduction()
Add a lightweight tracepoint to monitor TCP congestion window
adjustments via tcp_cwnd_reduction(). This tracepoint enables tracking
of:
- TCP window size fluctuations
- Active socket behavior
- Congestion window reduction events
Meta has been using BPF programs to monitor this function for years.
Adding a proper tracepoint provides a stable API for all users who need
to monitor TCP congestion window behavior.
Use DECLARE_TRACE instead of TRACE_EVENT to avoid creating trace event
infrastructure and exporting to tracefs, keeping the implementation
minimal. (Thanks Steven Rostedt)
Given that this patch creates a rawtracepoint, you could hook into it
using regular tooling, like bpftrace, using regular rawtracepoint
infrastructure, such as:
rawtracepoint:tcp_cwnd_reduction_tp {
....
}
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250214-cwnd_tracepoint-v2-1-ef8d15162d95@debian.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | include/trace/events/tcp.h | 6 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 2 |
2 files changed, 8 insertions, 0 deletions
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h index a27c4b619dff..1a40c41ff8c3 100644 --- a/include/trace/events/tcp.h +++ b/include/trace/events/tcp.h @@ -259,6 +259,12 @@ TRACE_EVENT(tcp_retransmit_synack, __entry->saddr_v6, __entry->daddr_v6) ); +DECLARE_TRACE(tcp_cwnd_reduction_tp, + TP_PROTO(const struct sock *sk, int newly_acked_sacked, + int newly_lost, int flag), + TP_ARGS(sk, newly_acked_sacked, newly_lost, flag) +); + #include <trace/events/net_probe_common.h> TRACE_EVENT(tcp_probe, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 074406890552..fbb67a098543 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2709,6 +2709,8 @@ void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, if (newly_acked_sacked <= 0 || WARN_ON_ONCE(!tp->prior_cwnd)) return; + trace_tcp_cwnd_reduction_tp(sk, newly_acked_sacked, newly_lost, flag); + tp->prr_delivered += newly_acked_sacked; if (delta < 0) { u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered + |