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[146.241.89.107]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f258dab74sm15132973f8f.32.2025.02.18.04.53.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Feb 2025 04:53:16 -0800 (PST) Message-ID: Date: Tue, 18 Feb 2025 13:53:15 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v2] trace: tcp: Add tracepoint for tcp_cwnd_reduction() To: Breno Leitao Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, kernel-team@meta.com, Jakub Kicinski , Eric Dumazet , David Ahern , Steven Rostedt , Masami Hiramatsu , "David S. Miller" , Simon Horman , Neal Cardwell References: <20250214-cwnd_tracepoint-v2-1-ef8d15162d95@debian.org> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250214-cwnd_tracepoint-v2-1-ef8d15162d95@debian.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 2/14/25 6:07 PM, Breno Leitao wrote: > 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 > --- > --- > Changes in v2: > - Close the parenthesis in a new line to honor the tcp.h format (Jakub). > - Add the bpftrace example in the commit message (Jakub) > - Link to v1: https://lore.kernel.org/r/20250207-cwnd_tracepoint-v1-1-13650f3ca96d@debian.org For future similar situations, note that it's expected to carry-on the tag already collected in the previous versions, since the delta is only cosmetic. No further actions required on your side. Cheers, Paolo