linux-kernel - Re: [PATCH net v3 2/4] trace: tcp: add three metrics to trace_tcp_rcvbuf

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Message-ID: <CADVnQy=NBw3RL+yS4=4AusooKkiMx9Wr+20dj-14fK+jPNw8pw@mail.gmail.com>
Date: Wed, 29 Oct 2025 09:41:47 -0400
From: Neal Cardwell <ncardwell@...gle.com>
To: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	"David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Simon Horman <horms@...nel.org>, David Ahern <dsahern@...nel.org>, 
	Mat Martineau <martineau@...nel.org>, Geliang Tang <geliang@...nel.org>, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, mptcp@...ts.linux.dev, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH net v3 2/4] trace: tcp: add three metrics to trace_tcp_rcvbuf_grow()

On Tue, Oct 28, 2025 at 7:58 AM Matthieu Baerts (NGI0)
<matttbe@...nel.org> wrote:
>
> From: Eric Dumazet <edumazet@...gle.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@...gle.com>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
> ---

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

Thanks, Eric and Matthieu!

neal