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

[Ian Rogers]

On Mon, Mar 30, 2026 at 1:14 PM Namhyung Kim <namhyung@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
>  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);
}
```

Thanks,
Ian

>  out:
>         if (err) {
>                 perf_env__exit(&trace->host_env);
> --
> 2.53.0.1185.g05d4b7b318-goog
>