netdev - Re: [PATCH net-next] trace: tcp: Add tracepoint for tcp

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Message-ID: <20250226-daft-inchworm-of-love-3a98c2@leitao>
Date: Wed, 26 Feb 2025 10:18:29 -0800
From: Breno Leitao <leitao@...ian.org>
To: David Ahern <dsahern@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	"David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
	kernel-team@...a.com, yonghong.song@...ux.dev
Subject: Re: [PATCH net-next] trace: tcp: Add tracepoint for tcp_sendmsg()

Hello David,

On Wed, Feb 26, 2025 at 10:12:08AM -0700, David Ahern wrote:
> On 2/26/25 9:10 AM, Breno Leitao wrote:
> >> Also, if a tracepoint is added, inside of tcp_sendmsg_locked would cover
> >> more use cases (see kernel references to it).
> > 
> > Agree, this seems to provide more useful information
> > 
> >> We have a patch for a couple years now with a tracepoint inside the
> > 
> > Sorry, where do you have this patch? is it downstream?
> 
> company tree. Attached. Where to put tracepoints and what arguments to
> supply so that it is beneficial to multiple users is always a touchy
> subject :-)

Thanks. I would like to state that this would be useful for Meta as
well.

Right now, we (Meta) are using nasty `noinline` attribute in
tcp_sendmsg() in order to make the API stable, and this tracepoint would
solve this problem avoiding the `noinline` hack. So, at least two type
of users would benefit from it.

> so I have not tried to push the patch out. sock arg should
> be added to it for example.

True, if it becomes a tracepoint instead of a rawtracepoint, the sock
arg might be useful.

How would you recommend me proceeding in this case?

Thanks
--breno