Re: [RFC/PATCH] perf stat: Show sample events stat for a data file

[Jiri Olsa]

On Wed, Apr 29, 2015 at 04:27:45PM +0900, Namhyung Kim wrote:
> Add --input option to 'perf stat' so that it can show event stats of the
> file.  I would like to use a short '-i' option to be compatible with
> other commands but it was already taken by '--no-inherit' option, so it
> only supports the long option.
> 
> 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 stat --input perf.data

nice, but maybe I'd see this under 'perf data' command, like:

    $ perf data --stat

'perf stat' does not deal with sampling..  I think that 'perf data'
is for perf.data related stuff like:

  perf data convert ...
  perf data ls
  perf data --features
  perf data --stat
  ...

thoughts? ;-)

jirka

> 
>     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@xxxxxxxxxx>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> ---
>  tools/perf/builtin-stat.c | 91 +++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 89 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index fd577f725d23..78ded82df4a9 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -58,6 +58,7 @@
>  #include "util/cpumap.h"
>  #include "util/thread.h"
>  #include "util/thread_map.h"
> +#include "util/hist.h"
>  
>  #include <stdlib.h>
>  #include <sys/prctl.h>
> @@ -1576,6 +1577,87 @@ static int perf_stat_init_aggr_mode(void)
>  	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(void)
> +{
> +	struct perf_data_file file = {
> +		.mode  = PERF_DATA_MODE_READ,
> +		.path  = input_name,
> +	};
> +	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)
> +		return ret;
> +
> +	nr_cpus = session->header.env.nr_cpus_online;
> +	sample_nsec = last_sample_nsec - first_sample_nsec;
> +
> +	fprintf(output, "\n Total event stats for '%s' file:\n\n", input_name);
> +	events_stats__fprintf(&session->evlist->stats, output);
> +
> +	fprintf(output, "\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];
> +
> +		fprintf(output, "%'18"PRIu64"      ", total_period);
> +		fprintf(output, "%-25s", perf_evsel__name(evsel));
> +		fprintf(output, "\n");
> +		fprintf(output, "%'18u      ", nr_samples);
> +		fprintf(output, "%-25s", "samples");
> +
> +		if (sample_nsec && evsel->attr.freq && evsel->attr.sample_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;
> +			fprintf(output, " #   sampling ratio  %.3f%% (%d/%d)",
> +				100 * sample_rate / expected_rate,
> +				(int)sample_rate, expected_rate);
> +		}
> +		fprintf(output, "\n\n");
> +	}
> +
> +	fprintf(output, "%18.9f second time sampled\n",
> +		(double)sample_nsec / NSEC_PER_SEC);
> +
> +	perf_session__delete(session);
> +	return 0;
> +}
> +
>  static int setup_events(const char * const *attrs, unsigned len)
>  {
>  	unsigned i;
> @@ -1793,6 +1875,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
>  		   "print counts with custom separator"),
>  	OPT_CALLBACK('G', "cgroup", &evsel_list, "name",
>  		     "monitor event in cgroup name only", parse_cgroups),
> +	OPT_STRING(0, "input", &input_name, "file", "input file name"),
>  	OPT_STRING('o', "output", &output_name, "file", "output file name"),
>  	OPT_BOOLEAN(0, "append", &append_file, "append to the output file"),
>  	OPT_INTEGER(0, "log-fd", &output_fd,
> @@ -1886,8 +1969,12 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
>  	} else if (big_num_opt == 0) /* User passed --no-big-num */
>  		big_num = false;
>  
> -	if (!argc && target__none(&target))
> -		usage_with_options(stat_usage, options);
> +	if (!argc && target__none(&target)) {
> +		if (!input_name)
> +			usage_with_options(stat_usage, options);
> +		status = show_sample_stat();
> +		goto out;
> +	}
>  
>  	if (run_count < 0) {
>  		pr_err("Run count must be a positive number\n");
> -- 
> 2.3.5
> 
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