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

Eric Dumazet
2025-02-26T18:27:37Z

On Wed, Feb 26, 2025 at 7:18 PM Breno Leitao <leitao@debian.org> wrote:
>
> 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?

In 2022, Menglong Dong added __fix_address

Then later , Yafang Shao added noinline_for_tracing .

Would one of them be sufficient ?