Re: [PATCH v4 06/11] perf evsel: Add function to compute group PMU name

[Ian Rogers]

On Mon, Mar 13, 2023 at 1:41 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> Em Wed, Mar 08, 2023 at 02:59:07PM -0800, Ian Rogers escreveu:
> > The computed name respects software events and aux event groups, such
> > that the pmu_name is changed to be that of the aux event leader or
> > group leader for software events. This is done as a later change will
> > split events that are in different PMUs into different groups.
>
> This makes 'perf test python' to fail:
>
> ⬢[acme@toolbox perf-tools-next]$ perf test -v python
> Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
>  19: 'import perf' in python                                         :
> --- start ---
> test child forked, pid 720242
> python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf-tools-next/python'); import perf" | '/usr/bin/python3' "
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> ImportError: /tmp/build/perf-tools-next/python/perf.cpython-311-x86_64-linux-gnu.so: undefined symbol: evsel__is_aux_event
> test child finished with -1
> ---- end ----
> 'import perf' in python: FAILED!
> ⬢[acme@toolbox perf-tools-next]$
>
> So I added the following patch, please run 'perf test' and 'make -C
> tools/perf build-test' before submitting patch series.
>
> - Arnaldo

Hmm.. was passing for me:

```
 19: 'import perf' in python                                         :
--- start ---
test child forked, pid 3161744
python usage test: "echo "import sys ;
sys.path.append('/tmp/perf/python'); import perf" | '/usr/bin/python3'
"
test child finished with 0
---- end ----
'import perf' in python: Ok
```

albeit:
```
$ nm /tmp/perf/python/perf.cpython-310-x86_64-linux-gnu.so |grep is_aux_event
                U evsel__is_aux_event
```

Perhaps there's some more aggressive linking flag I need to enable.

Thanks,
Ian

> diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
> index ab48ffbb644805df..be336f1b2b689602 100644
> --- a/tools/perf/util/python.c
> +++ b/tools/perf/util/python.c
> @@ -93,6 +93,11 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
>         return EOF;
>  }
>
> +bool evsel__is_aux_event(const struct evsel *evsel __maybe_unused)
> +{
> +       return false;
> +}
> +
>  /*
>   * Add this one here not to drag util/metricgroup.c
>   */
>
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > ---
> >  tools/perf/util/evsel.c | 24 ++++++++++++++++++++++++
> >  tools/perf/util/evsel.h |  1 +
> >  2 files changed, 25 insertions(+)
> >
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index 2dc2c24252bb..51d9650267d0 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -821,6 +821,30 @@ const char *evsel__name(struct evsel *evsel)
> >       return "unknown";
> >  }
> >
> > +const char *evsel__group_pmu_name(const struct evsel *evsel)
> > +{
> > +     const struct evsel *leader;
> > +
> > +     /* If the pmu_name is set use it. pmu_name isn't set for CPU and software events. */
> > +     if (evsel->pmu_name)
> > +             return evsel->pmu_name;
> > +     /*
> > +      * Software events may be in a group with other uncore PMU events. Use
> > +      * the pmu_name of the group leader to avoid breaking the software event
> > +      * out of the group.
> > +      *
> > +      * Aux event leaders, like intel_pt, expect a group with events from
> > +      * other PMUs, so substitute the AUX event's PMU in this case.
> > +      */
> > +     leader  = evsel__leader(evsel);
> > +     if ((evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) &&
> > +         leader->pmu_name) {
> > +             return leader->pmu_name;
> > +     }
> > +
> > +     return "cpu";
> > +}
> > +
> >  const char *evsel__metric_id(const struct evsel *evsel)
> >  {
> >       if (evsel->metric_id)
> > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> > index 676c499323e9..d26745ca6147 100644
> > --- a/tools/perf/util/evsel.h
> > +++ b/tools/perf/util/evsel.h
> > @@ -280,6 +280,7 @@ int arch_evsel__hw_name(struct evsel *evsel, char *bf, size_t size);
> >
> >  int __evsel__hw_cache_type_op_res_name(u8 type, u8 op, u8 result, char *bf, size_t size);
> >  const char *evsel__name(struct evsel *evsel);
> > +const char *evsel__group_pmu_name(const struct evsel *evsel);
> >  const char *evsel__metric_id(const struct evsel *evsel);
> >
> >  static inline bool evsel__is_tool(const struct evsel *evsel)
> > --
> > 2.40.0.rc0.216.gc4246ad0f0-goog
> >
>
> --
>
> - Arnaldo