This is a note to let you know that I've just added the patch titled
perf stat: Separate bperf from bpf_profiler
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-stat-separate-bperf-from-bpf_profiler.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0b2e9bd62c437e6cc33a177ec2d3bfd6ad3dbc99
Author: Dmitrii Dolgov <9erthalion6@xxxxxxxxx>
Date: Wed Apr 12 20:23:16 2023 +0200
perf stat: Separate bperf from bpf_profiler
[ 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@xxxxxxxxxx>
Signed-off-by: Dmitrii Dolgov <9erthalion6@xxxxxxxxx>
Tested-by: Song Liu <song@xxxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230412182316.11628-1-9erthalion6@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 387dc9c9e7bee..682db49eef4cb 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -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,
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index d572be41b9608..2899c97d997cd 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -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];
