From: Eric Dumazet <edumazet@google.com>

While chasing yet another receive autotuning bug,
I found useful to add rcv_ssthresh, window_clamp and rcv_wnd.

tcp_stream 40597 [068]  2172.978198: tcp:tcp_rcvbuf_grow: time=50307 rtt_us=50179 copied=77824 inq=0 space=40960 ooo=0 scaling_ratio=219 rcvbuf=131072 rcv_ssthresh=107474 window_clamp=112128 rcv_wnd=110592
tcp_stream 40597 [068]  2173.028528: tcp:tcp_rcvbuf_grow: time=50336 rtt_us=50206 copied=110592 inq=0 space=77824 ooo=0 scaling_ratio=219 rcvbuf=509444 rcv_ssthresh=328658 window_clamp=435813 rcv_wnd=331776
tcp_stream 40597 [068]  2173.078830: tcp:tcp_rcvbuf_grow: time=50305 rtt_us=50070 copied=270336 inq=0 space=110592 ooo=0 scaling_ratio=219 rcvbuf=509444 rcv_ssthresh=431159 window_clamp=435813 rcv_wnd=434176
tcp_stream 40597 [068]  2173.129137: tcp:tcp_rcvbuf_grow: time=50313 rtt_us=50118 copied=434176 inq=0 space=270336 ooo=0 scaling_ratio=219 rcvbuf=2457847 rcv_ssthresh=1299511 window_clamp=2102611 rcv_wnd=1302528
tcp_stream 40597 [068]  2173.179451: tcp:tcp_rcvbuf_grow: time=50318 rtt_us=50041 copied=1019904 inq=0 space=434176 ooo=0 scaling_ratio=219 rcvbuf=2457847 rcv_ssthresh=2087445 window_clamp=2102611 rcv_wnd=2088960

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
To: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-trace-kernel@vger.kernel.org
---
 include/trace/events/tcp.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 9d2c36c6a0ed..6757233bd064 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -218,6 +218,9 @@ TRACE_EVENT(tcp_rcvbuf_grow,
 		__field(__u32, space)
 		__field(__u32, ooo_space)
 		__field(__u32, rcvbuf)
+		__field(__u32, rcv_ssthresh)
+		__field(__u32, window_clamp)
+		__field(__u32, rcv_wnd)
 		__field(__u8, scaling_ratio)
 		__field(__u16, sport)
 		__field(__u16, dport)
@@ -245,6 +248,9 @@ TRACE_EVENT(tcp_rcvbuf_grow,
 				     tp->rcv_nxt;
 
 		__entry->rcvbuf = sk->sk_rcvbuf;
+		__entry->rcv_ssthresh = tp->rcv_ssthresh;
+		__entry->window_clamp = tp->window_clamp;
+		__entry->rcv_wnd = tp->rcv_wnd;
 		__entry->scaling_ratio = tp->scaling_ratio;
 		__entry->sport = ntohs(inet->inet_sport);
 		__entry->dport = ntohs(inet->inet_dport);
@@ -264,11 +270,14 @@ TRACE_EVENT(tcp_rcvbuf_grow,
 	),
 
 	TP_printk("time=%u rtt_us=%u copied=%u inq=%u space=%u ooo=%u scaling_ratio=%u rcvbuf=%u "
+		  "rcv_ssthresh=%u window_clamp=%u rcv_wnd=%u "
 		  "family=%s sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 "
 		  "saddrv6=%pI6c daddrv6=%pI6c skaddr=%p sock_cookie=%llx",
 		  __entry->time, __entry->rtt_us, __entry->copied,
 		  __entry->inq, __entry->space, __entry->ooo_space,
 		  __entry->scaling_ratio, __entry->rcvbuf,
+		  __entry->rcv_ssthresh, __entry->window_clamp,
+		  __entry->rcv_wnd,
 		  show_family_name(__entry->family),
 		  __entry->sport, __entry->dport,
 		  __entry->saddr, __entry->daddr,

-- 
2.51.0

On Tue, Oct 28, 2025 at 7:58 AM Matthieu Baerts (NGI0)
<matttbe@kernel.org> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> While chasing yet another receive autotuning bug,
> I found useful to add rcv_ssthresh, window_clamp and rcv_wnd.
>
> tcp_stream 40597 [068]  2172.978198: tcp:tcp_rcvbuf_grow: time=50307 rtt_us=50179 copied=77824 inq=0 space=40960 ooo=0 scaling_ratio=219 rcvbuf=131072 rcv_ssthresh=107474 window_clamp=112128 rcv_wnd=110592
> tcp_stream 40597 [068]  2173.028528: tcp:tcp_rcvbuf_grow: time=50336 rtt_us=50206 copied=110592 inq=0 space=77824 ooo=0 scaling_ratio=219 rcvbuf=509444 rcv_ssthresh=328658 window_clamp=435813 rcv_wnd=331776
> tcp_stream 40597 [068]  2173.078830: tcp:tcp_rcvbuf_grow: time=50305 rtt_us=50070 copied=270336 inq=0 space=110592 ooo=0 scaling_ratio=219 rcvbuf=509444 rcv_ssthresh=431159 window_clamp=435813 rcv_wnd=434176
> tcp_stream 40597 [068]  2173.129137: tcp:tcp_rcvbuf_grow: time=50313 rtt_us=50118 copied=434176 inq=0 space=270336 ooo=0 scaling_ratio=219 rcvbuf=2457847 rcv_ssthresh=1299511 window_clamp=2102611 rcv_wnd=1302528
> tcp_stream 40597 [068]  2173.179451: tcp:tcp_rcvbuf_grow: time=50318 rtt_us=50041 copied=1019904 inq=0 space=434176 ooo=0 scaling_ratio=219 rcvbuf=2457847 rcv_ssthresh=2087445 window_clamp=2102611 rcv_wnd=2088960
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> ---

Reviewed-by: Neal Cardwell <ncardwell@google.com>

Thanks, Eric and Matthieu!

neal