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

[Breno Leitao]

Hello Paolo,

On Tue, Feb 18, 2025 at 01:53:15PM +0100, Paolo Abeni wrote:
> 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 <leitao@xxxxxxxxxx>
> > ---
> > ---
> > 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@xxxxxxxxxx
> 
> 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.

That is fair. I simply forgot about it. Sorry about it.