Re: [PATCH net-next v2] trace: tcp: Add tracepoint for tcp_cwnd_reduction()

[Eric Dumazet]

On Fri, Feb 14, 2025 at 6:07 PM Breno Leitao <leitao@xxxxxxxxxx> 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 <leitao@xxxxxxxxxx>

Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>