Re: [PATCH v1 1/2] perf stat: Clear reset_group for each stat run

[Xing Zhengjun]

On 8/23/2022 5:33 AM, Ian Rogers wrote:
> If a weak group is broken then the reset_group flag remains set for
> the next run. Having reset_group set means the counter isn't created
> and ultimately a segfault.
>
> A simple reproduction of this is:
> perf stat -r2 -e '{cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles}:W

It is better to change to a full command:
perf stat -r2 -e 
'{cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles,cycles}:W' 
true
> which will be added as a test in the next patch.
>
> Fixes: 4804e0111662 ("perf stat: Use affinity for opening events")
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>

I test the two patches on both non-hybrid and hybrid machines, and the 
"Segmentation fault" disappeared.

Tested-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>

> ---
>   tools/perf/builtin-stat.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 7fb81a44672d..54cd29d07ca8 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -826,6 +826,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>   	}
>   
>   	evlist__for_each_entry(evsel_list, counter) {
> +		counter->reset_group = false;
>   		if (bpf_counter__load(counter, &target))
>   			return -1;
>   		if (!evsel__is_bpf(counter))

--
Zhengjun Xing