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    SubjectRe: [PATCH v3] perf record: encode -k clockid frequency into Perf trace
    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,
    > };

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