Re: [PATCH dwarves] pahole, btf_encoder: Collect info of per-cpu varaibles from threads.

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Mar 25, 2022 at 04:02:13PM -0700, Andrii Nakryiko escreveu:
> On Mon, Mar 21, 2022 at 4:08 PM Kui-Feng Lee <kuifeng@fb.com> wrote:
> >
> > Collect the information of per-cpu variables from encoders of worker
> > threads to the primary encoder.
> >
> > btf_encoder store per-cpu info separately, not in btf.  Previously, it
> > merged only btf types generated by worker threads.  So, some of the
> > per-cpu info was missing.
> >
> > Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
> > ---
> 
> I've applied this locally and tested, it all looks good, thanks! I'm
> keeping this applied locally until Arnaldo pushes this to master :)
> 
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> Tested-by: Andrii Nakryiko <andrii@kernel.org>

And from a quick look the code is really elegant, well done!

Applied and will push to the next branch, later today/tomorrow I'll push
it out to master after it passes the libbpf CI tests.
 
Thanks!

- Arnaldo

> >  btf_encoder.c | 21 +++++++++++++++++++++
> >  btf_encoder.h |  2 ++
> >  pahole.c      |  2 +-
> >  3 files changed, 24 insertions(+), 1 deletion(-)
> >
> > diff --git a/btf_encoder.c b/btf_encoder.c
> > index fa29824..1a42094 100644
> > --- a/btf_encoder.c
> > +++ b/btf_encoder.c
> > @@ -606,6 +606,27 @@ static int32_t btf_encoder__add_var_secinfo(struct btf_encoder *encoder, uint32_
> >         return gobuffer__add(&encoder->percpu_secinfo, &si, sizeof(si));
> >  }
> >
> > +int32_t btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other)
> > +{
> > +       struct gobuffer *var_secinfo_buf = &other->percpu_secinfo;
> > +       size_t sz = gobuffer__size(var_secinfo_buf);
> > +       uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
> > +       uint32_t type_id;
> > +       uint32_t next_type_id = btf__type_cnt(encoder->btf);
> > +       int32_t i, id;
> > +       struct btf_var_secinfo *vsi;
> > +
> > +       for (i = 0; i < nr_var_secinfo; i++) {
> > +               vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + i;
> > +               type_id = next_type_id + vsi->type - 1; /* Type ID starts from 1 */
> > +               id = btf_encoder__add_var_secinfo(encoder, type_id, vsi->offset, vsi->size);
> > +               if (id < 0)
> > +                       return id;
> > +       }
> > +
> > +       return btf__add_btf(encoder->btf, other->btf);
> > +}
> > +
> >  static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char *section_name)
> >  {
> >         struct gobuffer *var_secinfo_buf = &encoder->percpu_secinfo;
> > diff --git a/btf_encoder.h b/btf_encoder.h
> > index 0f0eee8..339fae2 100644
> > --- a/btf_encoder.h
> > +++ b/btf_encoder.h
> > @@ -31,4 +31,6 @@ struct btf_encoder *btf_encoders__next(struct btf_encoder *encoder);
> >
> >  struct btf *btf_encoder__btf(struct btf_encoder *encoder);
> >
> > +int btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other);
> > +
> >  #endif /* _BTF_ENCODER_H_ */
> > diff --git a/pahole.c b/pahole.c
> > index f7c7966..a909b22 100644
> > --- a/pahole.c
> > +++ b/pahole.c
> > @@ -2867,7 +2867,7 @@ static int pahole_threads_collect(struct conf_load *conf, int nr_threads, void *
> >                  */
> >                 if (!threads[i]->btf || threads[i]->encoder == btf_encoder)
> >                         continue; /* The primary btf_encoder */
> > -               err = btf__add_btf(btf_encoder__btf(btf_encoder), threads[i]->btf);
> > +               err = btf_encoder__add_encoder(btf_encoder, threads[i]->encoder);
> >                 if (err < 0)
> >                         goto out;
> >                 btf_encoder__delete(threads[i]->encoder);
> > --
> > 2.30.2
> >

-- 

- Arnaldo