Re: [PATCH] perf trace: Skip unnecessary synthesis for summary-only mode

[Namhyung Kim <namhyung@kernel.org>]

On Mon, Mar 30, 2026 at 02:00:08PM -0700, Ian Rogers wrote:
> On Mon, Mar 30, 2026 at 1:14 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > It needs to synthesize task info for the comm name.  The mmap
> > information is only needed for callchain symbolization which is not used
> > by the summary mode.  Also total or cgroup summary mode don't require
> > the task info.  Let's skip the processing if possible.
> >
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> >  tools/perf/builtin-trace.c | 22 +++++++++++++++++-----
> >  1 file changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> > index f487fbaa0ad60028..d09d78b3222717d1 100644
> > --- a/tools/perf/builtin-trace.c
> > +++ b/tools/perf/builtin-trace.c
> > @@ -2004,11 +2004,23 @@ static int trace__symbols_init(struct trace *trace, int argc, const char **argv,
> >         if (err < 0)
> >                 goto out;
> >
> > -       err = __machine__synthesize_threads(trace->host, &trace->tool, &trace->opts.target,
> > -                                           evlist->core.threads, trace__tool_process,
> > -                                           /*needs_mmap=*/callchain_param.enabled,
> > -                                           /*mmap_data=*/false,
> > -                                           /*nr_threads_synthesize=*/1);
> > +       if (trace->summary_only) {
> > +               if (trace->summary_mode == SUMMARY__BY_THREAD) {
> > +                       err = __machine__synthesize_threads(trace->host, &trace->tool,
> > +                                                           &trace->opts.target,
> > +                                                           evlist->core.threads,
> > +                                                           trace__tool_process,
> > +                                                           /*needs_mmap=*/false,
> > +                                                           /*mmap_data=*/false,
> > +                                                           /*nr_threads_synthesize=*/1);
> > +               }
> > +       } else {
> > +               err = __machine__synthesize_threads(trace->host, &trace->tool, &trace->opts.target,
> > +                                                   evlist->core.threads, trace__tool_process,
> > +                                                   /*needs_mmap=*/callchain_param.enabled,
> > +                                                   /*mmap_data=*/false,
> > +                                                   /*nr_threads_synthesize=*/1);
> > +       }
> 
> Could this be simplified to something like:
> ```
> if (!trace->summary_only || trace->summary_mode == SUMMARY__BY_THREAD) {
>        err = __machine__synthesize_threads(trace->host, &trace->tool,
> &trace->opts.target,
>                                            evlist->core.threads,
> trace__tool_process,
> 
> /*needs_mmap=*/callchain_param.enabled && !trace->summary_only,
>                                            /*mmap_data=*/false,
>                                            /*nr_threads_synthesize=*/1);
> }
> ```

Looks good, will update.

Btw, it'd be nice if you could find a mail client that can turn off the
line wrapping. :)

Thanks,
Namhyung