mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

perf stat: Separate bperf from bpf_profiler 

[ Upstream commit ecc68ee216 ]

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: 112cb56164 ("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>
This commit is contained in:
Dmitrii Dolgov 2023-04-12 20:23:16 +02:00 committed by Greg Kroah-Hartman
parent 2da5799fa0
commit e50996c159
2 changed files with 7 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
tools/perf/builtin-stat.c
View File

@ -773,7 +773,7 @@ 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;
}
@ -789,7 +789,7 @@ 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,

5
tools/perf/util/evsel.h
View File

@ -269,6 +269,11 @@ 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];