From: Dmitrii Dolgov 9erthalion6@gmail.com
[ Upstream commit ecc68ee216c6c5b2f84915e1441adf436f1b019b ]
It seems that perf stat -b <prog id> doesn't produce any results:
$ perf stat -e cycles -b 4 -I 10000 -vvv Control descriptor is not initialized cycles: 0 0 0 time counts unit events 10.007641640 <not supported> cycles
Looks like this happens because fentry/fexit progs are getting loaded, but the corresponding perf event is not enabled and not added into the events bpf map. I think there is some mixing up between two type of bpf support, one for bperf and one for bpf_profiler. Both are identified via evsel__is_bpf, based on which perf events are enabled, but for the latter (bpf_profiler) a perf event is required. Using evsel__is_bperf to check only bperf produces expected results:
$ perf stat -e cycles -b 4 -I 10000 -vvv Control descriptor is not initialized ------------------------------------------------------------ perf_event_attr: size 136 sample_type IDENTIFIER read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING disabled 1 exclude_guest 1 ------------------------------------------------------------ sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 3 ------------------------------------------------------------ [...perf_event_attr for other CPUs...] ------------------------------------------------------------ cycles: 309426 169009 169009 time counts unit events 10.010091271 309426 cycles
The final numbers correspond (at least in the level of magnitude) to the same metric obtained via bpftool.
Fixes: 112cb56164bc2108 ("perf stat: Introduce config stat.bpf-counter-events") Reviewed-by: Song Liu song@kernel.org Signed-off-by: Dmitrii Dolgov 9erthalion6@gmail.com Tested-by: Song Liu song@kernel.org Cc: Ian Rogers irogers@google.com Cc: Ingo Molnar mingo@redhat.com Cc: Jiri Olsa jolsa@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20230412182316.11628-1-9erthalion6@gmail.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-stat.c | 4 ++-- tools/perf/util/evsel.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index f6427e3a47421..a2c74a34e4a44 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -765,7 +765,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx) counter->reset_group = false; if (bpf_counter__load(counter, &target)) return -1; - if (!evsel__is_bpf(counter)) + if (!(evsel__is_bperf(counter))) all_counters_use_bpf = false; }
@@ -781,7 +781,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
if (counter->reset_group || counter->errored) continue; - if (evsel__is_bpf(counter)) + if (evsel__is_bperf(counter)) continue; try_again: if (create_perf_stat_counter(counter, &stat_config, &target, diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 989865e16aadd..8ce30329a0772 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -263,6 +263,11 @@ static inline bool evsel__is_bpf(struct evsel *evsel) return evsel->bpf_counter_ops != NULL; }
+static inline bool evsel__is_bperf(struct evsel *evsel) +{ + return evsel->bpf_counter_ops != NULL && list_empty(&evsel->bpf_counter_list); +} + #define EVSEL__MAX_ALIASES 8
extern const char *const evsel__hw_cache[PERF_COUNT_HW_CACHE_MAX][EVSEL__MAX_ALIASES];