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Subject[RFC/PATCH v2] perf data: Add stat subcommand to show sample event stat
Date
Add stat subbcommand to 'perf data' so that it can show various event
stats in the file.

The example output looks like below:

$ perf record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.635 MB perf.data (1946 samples) ]

$ perf data stat

Total event stats for 'perf.data' file:

TOTAL events: 6837
MMAP events: 116
COMM events: 375
EXIT events: 2
THROTTLE events: 12
UNTHROTTLE events: 11
FORK events: 374
SAMPLE events: 1946
MMAP2 events: 3999
FINISHED_ROUND events: 2

Sample event stats:

361,255,234 cycles
1,946 samples # sampling ratio 12.162% (486/4000)

0.998581085 second time sampled

The sampling ratio was useful for me to determine how often the event
was sampled - in this case the cpu cycles event was only sampled at 12%
of the expected sampling frequency, so the system was mostly idle in
terms of cpu cycles (or the event was multiplexed in case of recording
large number of events at once).

The sampling ratio was calulated like below:

expected_freq = evsel->attr.sample_freq
actual_freq = (nr_samples / nr_cpus) / sample_time
sampling_ratio = 100 * actual_freq / expected_freq

Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
* move it to 'perf data' rather than 'perf stat'
* show event rate for non-freq events

tools/perf/builtin-data.c | 130 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 129 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-data.c b/tools/perf/builtin-data.c
index d6525bc54d13..13031743f22c 100644
--- a/tools/perf/builtin-data.c
+++ b/tools/perf/builtin-data.c
@@ -4,6 +4,12 @@
#include "debug.h"
#include "parse-options.h"
#include "data-convert-bt.h"
+#include "hist.h"
+#include "data.h"
+#include "session.h"
+#include "evlist.h"
+
+#include <locale.h>

typedef int (*data_cmd_fn_t)(int argc, const char **argv, const char *prefix);

@@ -22,7 +28,7 @@ static const struct option data_options[] = {
OPT_END()
};

-static const char * const data_subcommands[] = { "convert", NULL };
+static const char * const data_subcommands[] = { "convert", "stat", NULL };

static const char *data_usage[] = {
"perf data [<common options>] <command> [<options>]",
@@ -88,8 +94,128 @@ static int cmd_data_convert(int argc, const char **argv,
return 0;
}

+static u64 first_sample_nsec;
+static u64 last_sample_nsec;
+
+static int process_sample_event(struct perf_tool *tool __maybe_unused,
+ union perf_event *event __maybe_unused,
+ struct perf_sample *sample,
+ struct perf_evsel *evsel,
+ struct machine *machine __maybe_unused)
+{
+ struct hists *hists = evsel__hists(evsel);
+
+ if (!first_sample_nsec)
+ first_sample_nsec = sample->time;
+ last_sample_nsec = sample->time;
+
+ hists->stats.total_period += sample->period;
+ hists->stats.nr_events[PERF_RECORD_SAMPLE]++;
+ return 0;
+}
+
+static int show_sample_stat(bool force)
+{
+ struct perf_data_file file = {
+ .mode = PERF_DATA_MODE_READ,
+ .path = input_name,
+ .force = force,
+ };
+ struct perf_tool tool = {
+ .sample = process_sample_event,
+ };
+ struct perf_session *session;
+ struct perf_evsel *evsel;
+ u64 sample_nsec;
+ int nr_cpus;
+ int ret;
+
+ session = perf_session__new(&file, false, &tool);
+ if (session == NULL)
+ return -1;
+
+ ret = perf_session__process_events(session);
+ if (ret < 0)
+ goto out;
+
+ nr_cpus = session->header.env.nr_cpus_online;
+ sample_nsec = last_sample_nsec - first_sample_nsec;
+
+ printf("\n Total event stats for '%s' file:\n\n", file.path);
+ events_stats__fprintf(&session->evlist->stats, stdout);
+
+ printf("\n Sample event stats:\n\n");
+ evlist__for_each(session->evlist, evsel) {
+ struct hists *hists = evsel__hists(evsel);
+ struct events_stats *stats = &hists->stats;
+ u64 total_period = stats->total_period;
+ u32 nr_samples = stats->nr_events[PERF_RECORD_SAMPLE];
+
+ printf("%'18"PRIu64" ", total_period);
+ printf("%-25s", perf_evsel__name(evsel));
+ printf("\n");
+ printf("%'18u ", nr_samples);
+ printf("%-25s", "samples");
+
+ if (sample_nsec == 0 || evsel->attr.sample_freq == 0)
+ goto next;
+
+ if (evsel->attr.freq) {
+ int expected_rate = evsel->attr.sample_freq;
+ double sample_rate = 1.0 * nr_samples / nr_cpus;
+
+ sample_rate *= (double)NSEC_PER_SEC / sample_nsec;
+ printf(" # sampling ratio %.3f%% (%d/%d)",
+ 100 * sample_rate / expected_rate,
+ (int)sample_rate, expected_rate);
+ } else {
+ double event_rate = NSEC_PER_SEC * nr_samples;
+
+ event_rate /= 1000 * sample_nsec;
+ printf(" # event rate %.3f (K/sec)", event_rate);
+ }
+
+next:
+ printf("\n\n");
+ }
+
+ printf("%18.9f second time sampled\n",
+ (double)sample_nsec / NSEC_PER_SEC);
+
+out:
+ perf_session__delete(session);
+ return ret;
+}
+
+
+static const char * const data_stat_usage[] = {
+ "perf data stat [<options>]",
+ NULL
+};
+
+static int cmd_data_stat(int argc, const char **argv,
+ const char *prefix __maybe_unused)
+{
+ bool force = false;
+ const struct option options[] = {
+ OPT_INCR('v', "verbose", &verbose, "be more verbose"),
+ OPT_STRING('i', "input", &input_name, "file", "input file name"),
+ OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
+ OPT_END()
+ };
+
+ argc = parse_options(argc, argv, options, data_stat_usage, 0);
+ if (argc) {
+ usage_with_options(data_stat_usage, options);
+ return -1;
+ }
+
+ return show_sample_stat(force);
+}
+
static struct data_cmd data_cmds[] = {
{ "convert", "converts data file between formats", cmd_data_convert },
+ { "stat", "show event stats in data file", cmd_data_stat },
{ .name = NULL, },
};

@@ -107,6 +233,8 @@ int cmd_data(int argc, const char **argv, const char *prefix)
if (argc < 1)
goto usage;

+ setlocale(LC_ALL, "");
+
cmdstr = argv[0];

for_each_cmd(cmd) {
--
2.4.0


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