Re: [PATCH v2] perf evlist: Fix 'perf record -C xx' failed issue

[Chunxin Zang <spring.cxz@gmail.com>]

Sorry, I'm a little out of it, maybe because I didn't sleep at noon. This version is deprecated, v1 is correct.

v1: https://lore.kernel.org/linux-kernel/20240319084022.2036296-1-spring.cxz@gmail.com/T/#u

Best wishes
Chunxin


> On Mar 19, 2024, at 17:14, Chunxin Zang <spring.cxz@gmail.com> wrote:
> 
> The cpu has 8 performance-cores and 8 efficient-cores on my pc.
> 0-15 are performance-cores
> 16-23 are 8 efficient-cores
> 
> When I run "perf record -C xxx", the command fails if xxx all belong to
> performance cores or efficient cores
> 
> The results are as follows
> 
>  # perf record -C 12
>  WARNING: A requested CPU in '12' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
>  Error:
>  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu_atom/cycles:P/).
>  /bin/dmesg | grep -i perf may provide additional information.
> 
>  # perf record -C 14-17
>  WARNING: A requested CPU in '14-17' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
>  WARNING: A requested CPU in '14-17' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'
>  ^C[ perf record: Woken up 1 times to write data ]
> 
> The reason is that the cpu_map of 'cpu_atom'-evsel is empty, causing
> the sys_perf_event_open() result to fail.
> 
> Changes in v2:
> - fix memory leak about 'intersect'
> 
> Signed-off-by: Chunxin Zang <spring.cxz@gmail.com>
> Reviewed-by: Chen Yang <yangchen11@lixiang.com>
> ---
> tools/perf/util/evlist.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 55a300a0977b..babbde29341f 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -2499,7 +2499,7 @@ void evlist__check_mem_load_aux(struct evlist *evlist)
> void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_list)
> {
> struct perf_cpu_map *user_requested_cpus;
> - struct evsel *pos;
> + struct evsel *pos, *tmp;
> 
> if (!cpu_list)
> return;
> @@ -2508,18 +2508,28 @@ void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_lis
> if (!user_requested_cpus)
> return;
> 
> - evlist__for_each_entry(evlist, pos) {
> + evlist__for_each_entry_safe(evlist, tmp, pos) {
> struct perf_cpu_map *intersect, *to_test;
> const struct perf_pmu *pmu = evsel__find_pmu(pos);
> 
> to_test = pmu && pmu->is_core ? pmu->cpus : cpu_map__online();
> intersect = perf_cpu_map__intersect(to_test, user_requested_cpus);
> - if (!perf_cpu_map__equal(intersect, user_requested_cpus)) {
> - char buf[128];
> + if (!intersect) {
> + evlist__remove(evlist, pos);
> + evsel__delete(pos);
> + perf_cpu_map__put(intersect);
> + continue;
> + }
> +
> + if (!perf_cpu_map__is_subset(user_requested_cpus, intersect)) {
> + char buf_test[128];
> + char buf_intersect[128];
> 
> - cpu_map__snprint(to_test, buf, sizeof(buf));
> - pr_warning("WARNING: A requested CPU in '%s' is not supported by PMU '%s' (CPUs %s) for event '%s'\n",
> - cpu_list, pmu ? pmu->name : "cpu", buf, evsel__name(pos));
> + cpu_map__snprint(to_test, buf_test, sizeof(buf_test));
> + cpu_map__snprint(intersect, buf_intersect, sizeof(buf_intersect));
> + pr_warning("WARNING: A requested CPU '%s' in '%s' is not supported by "
> +   "PMU '%s' (CPUs %s) for event '%s'\n", buf_intersect, cpu_list,
> +   pmu ? pmu->name : "cpu", buf_test, evsel__name(pos));
> }
> perf_cpu_map__put(intersect);
> }
> -- 
> 2.34.1
>