Re: [PATCH v3] perf record: encode -k clockid frequency into Perf trace

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Wed, Oct 03, 2018 at 07:57:12PM +0300, Alexey Budankov escreveu:
> 
> Store -k clockid frequency into Perf trace to enable timestamps 
> derived metrics conversion into wall clock time on reporting stage.

Humm, looking at where this is documented, we already have this in the
tools/perf/Documentation/perf-record.txt file, but it doesn't specify
how to select the option, just lists the CONFIG_MONOTONIC_FOO clocks,
leaving the user to figure that they have to use "-k raw" :-\

This is not a problem introduced by this patch, which works as
advertised:

  [acme@jouet perf]$ perf record -k raw sleep 0.1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ]
  [acme@jouet perf]$ perf evlist -v
  cycles:uppp: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, exclude_kernel: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, use_clockid: 1, clockid: 4
  [acme@jouet perf]$ 
  
Also that "clockid: 4" would be best as "clockid: raw" :-\

> Below is the example of perf report output:
> 
> tools/perf/perf record -k raw -- ../../matrix/linux/matrix.gcc
> ...
> [ perf record: Captured and wrote 31.222 MB perf.data (818054 samples) ]
> 
> tools/perf/perf report --header
> # ========
> ...
> # event : name = cycles:ppp, , size = 112, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|PERIOD, disabled = 1, inherit = 1, mmap = 1, comm = 1, freq = 1, enable_on_exec = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1, use_clockid = 1, clockid = 4
> ...
> # clockid frequency: 1000 MHz
> ...
> # ========

Please add two spaces before the output of programs, specially those
that start with a #, otherwise when applying they will vanish.

Fixed that up, applied!

- Arnaldo

> 
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> ---
> Changes in v3:
>  - moved header's clockid_res_ns initialization out of record__init_features()
>  - added explicit warning for case of failed clock_getres() call
> Changes in v2:
>  - renamed clockid_freq to clockid_res_ns and get_clockid_freq() to get_clockid_res()
>  - avoided redundant define of NSEC_IN_SEC, reused linux/time64.h:NSEC_PER_SEC
>  - moved MHz conversion into print_clockid() and shortened write_clockid()
> ---
>  tools/perf/builtin-record.c | 24 ++++++++++++++++++++++--
>  tools/perf/perf.h           |  1 +
>  tools/perf/util/env.h       |  1 +
>  tools/perf/util/header.c    | 27 +++++++++++++++++++++++++++
>  tools/perf/util/header.h    |  1 +
>  5 files changed, 52 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 0980dfe3396b..d803d3264465 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -592,6 +592,9 @@ static void record__init_features(struct record *rec)
>  	if (!rec->opts.full_auxtrace)
>  		perf_header__clear_feat(&session->header, HEADER_AUXTRACE);
>  
> +	if (!(rec->opts.use_clockid && rec->opts.clockid_res_ns))
> +		perf_header__clear_feat(&session->header, HEADER_CLOCKID);
> +
>  	perf_header__clear_feat(&session->header, HEADER_STAT);
>  }
>  
> @@ -897,6 +900,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>  
>  	record__init_features(rec);
>  
> +	if (rec->opts.use_clockid && rec->opts.clockid_res_ns)
> +		session->header.env.clockid_res_ns = rec->opts.clockid_res_ns;
> +
>  	if (forks) {
>  		err = perf_evlist__prepare_workload(rec->evlist, &opts->target,
>  						    argv, data->is_pipe,
> @@ -1337,6 +1343,19 @@ static const struct clockid_map clockids[] = {
>  	CLOCKID_END,
>  };
>  
> +static int get_clockid_res(clockid_t clk_id, size_t *res_ns)
> +{
> +	struct timespec res;
> +
> +	*res_ns = 0;
> +	if (!clock_getres(clk_id, &res))
> +		*res_ns = res.tv_nsec + res.tv_sec * NSEC_PER_SEC;
> +	else
> +		pr_warning("WARNING: Failed to determine specified clock resolution.\n");
> +
> +	return 0;
> +}
> +
>  static int parse_clockid(const struct option *opt, const char *str, int unset)
>  {
>  	struct record_opts *opts = (struct record_opts *)opt->value;
> @@ -1360,7 +1379,7 @@ static int parse_clockid(const struct option *opt, const char *str, int unset)
>  
>  	/* if its a number, we're done */
>  	if (sscanf(str, "%d", &opts->clockid) == 1)
> -		return 0;
> +		return get_clockid_res(opts->clockid, &opts->clockid_res_ns);
>  
>  	/* allow a "CLOCK_" prefix to the name */
>  	if (!strncasecmp(str, "CLOCK_", 6))
> @@ -1369,7 +1388,8 @@ static int parse_clockid(const struct option *opt, const char *str, int unset)
>  	for (cm = clockids; cm->name; cm++) {
>  		if (!strcasecmp(str, cm->name)) {
>  			opts->clockid = cm->clockid;
> -			return 0;
> +			return get_clockid_res(opts->clockid,
> +					       &opts->clockid_res_ns);
>  		}
>  	}
>  
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index 21bf7f5a3cf5..981db3c2ed60 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -81,6 +81,7 @@ struct record_opts {
>  	unsigned     initial_delay;
>  	bool         use_clockid;
>  	clockid_t    clockid;
> +	size_t       clockid_res_ns;
>  	unsigned int proc_map_timeout;
>  };
>  
> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
> index 1f3ccc368530..b167a54d635f 100644
> --- a/tools/perf/util/env.h
> +++ b/tools/perf/util/env.h
> @@ -63,6 +63,7 @@ struct perf_env {
>  	struct numa_node	*numa_nodes;
>  	struct memory_node	*memory_nodes;
>  	unsigned long long	 memory_bsize;
> +	size_t                   clockid_res_ns;
>  };
>  
>  extern struct perf_env perf_env;
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 1ec1d9bc2d63..4ce5339158f7 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1034,6 +1034,13 @@ static int write_auxtrace(struct feat_fd *ff,
>  	return err;
>  }
>  
> +static int write_clockid(struct feat_fd *ff,
> +			 struct perf_evlist *evlist __maybe_unused)
> +{
> +	return do_write(ff, &ff->ph->env.clockid_res_ns,
> +			sizeof(ff->ph->env.clockid_res_ns));
> +}
> +
>  static int cpu_cache_level__sort(const void *a, const void *b)
>  {
>  	struct cpu_cache_level *cache_a = (struct cpu_cache_level *)a;
> @@ -1508,6 +1515,12 @@ static void print_cpu_topology(struct feat_fd *ff, FILE *fp)
>  		fprintf(fp, "# Core ID and Socket ID information is not available\n");
>  }
>  
> +static void print_clockid(struct feat_fd *ff, FILE *fp)
> +{
> +	fprintf(fp, "# clockid frequency: %ld MHz\n",
> +		ff->ph->env.clockid_res_ns * 1000);
> +}
> +
>  static void free_event_desc(struct perf_evsel *events)
>  {
>  	struct perf_evsel *evsel;
> @@ -2531,6 +2544,19 @@ static int process_mem_topology(struct feat_fd *ff,
>  	return ret;
>  }
>  
> +static int process_clockid(struct feat_fd *ff,
> +			   void *data __maybe_unused)
> +{
> +	size_t clockid_res_ns;
> +
> +	if (do_read_u64(ff, &clockid_res_ns))
> +		return -1;
> +
> +	ff->ph->env.clockid_res_ns = clockid_res_ns;
> +
> +	return 0;
> +}
> +
>  struct feature_ops {
>  	int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
>  	void (*print)(struct feat_fd *ff, FILE *fp);
> @@ -2590,6 +2616,7 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
>  	FEAT_OPN(CACHE,		cache,		true),
>  	FEAT_OPR(SAMPLE_TIME,	sample_time,	false),
>  	FEAT_OPR(MEM_TOPOLOGY,	mem_topology,	true),
> +	FEAT_OPR(CLOCKID,       clockid,        false)
>  };
>  
>  struct header_print_data {
> diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
> index e17903caa71d..0d553ddca0a3 100644
> --- a/tools/perf/util/header.h
> +++ b/tools/perf/util/header.h
> @@ -38,6 +38,7 @@ enum {
>  	HEADER_CACHE,
>  	HEADER_SAMPLE_TIME,
>  	HEADER_MEM_TOPOLOGY,
> +	HEADER_CLOCKID,
>  	HEADER_LAST_FEATURE,
>  	HEADER_FEAT_BITS	= 256,
>  };