Re: [PATCH v1 1/4] perf stat: Allow no events to open if this is a "--null" run

From: Ingo Molnar
Date: Mon Dec 01 2025 - 23:38:44 EST



* Ian Rogers <irogers@xxxxxxxxxx> wrote:

> It is intended that a "--null" run doesn't open any events.
>
> Fixes: 2cc7aa995ce9 ("perf stat: Refactor retry/skip/fatal error handling")
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
> tools/perf/builtin-stat.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 5c06e9b61821..6410115ed9c5 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -923,7 +923,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
> goto err_out;
> }
> }
> - if (!has_supported_counters) {
> + if (!has_supported_counters && !stat_config.null_run) {
> evsel__open_strerror(evlist__first(evsel_list), &target, open_err,
> msg, sizeof(msg));
> ui__error("No supported events found.\n%s\n", msg);

Note that without the cpumask workaround patch I sent
'perf stat --null' still segfaults on perf-tools-next
even with the above patch applied - I suppose that's
expected, right?

Other than that:

Tested-by: Ingo Molnar <mingo@xxxxxxxxxx>

Thanks,

Ingo