[PATCH v1] perf record: encode -k clockid frequency into Perf trace

Alexey Budankov
2018-09-27T12:54:10Z

Store -k clockid frequency into Perf trace to enable timestamps
derived metrics conversion into wall clock time on reporting stage.

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
...
# ========

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
tools/perf/builtin-record.c | 26 ++++++++++++++++++++++++--
tools/perf/perf.h | 1 +
tools/perf/util/env.h | 1 +
tools/perf/util/header.c | 32 ++++++++++++++++++++++++++++++++
tools/perf/util/header.h | 1 +
5 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0980dfe3396b..f215daf28508 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -592,6 +592,11 @@ 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_freq)
+ session->header.env.clockid_freq = rec->opts.clockid_freq;
+ else
+ perf_header__clear_feat(&session->header, HEADER_CLOCKID);
+
perf_header__clear_feat(&session->header, HEADER_STAT);
}

@@ -1337,6 +1342,22 @@ static const struct clockid_map clockids[] = {
CLOCKID_END,
};

+#define NSEC_IN_SEC (1000 * 1000 * 1000)
+
+static int get_clockid_freq(clockid_t clk_id, size_t *freq)
+{
+ size_t period_ns;
+ struct timespec res;
+
+ *freq = 0;
+ if (!clock_getres(clk_id, &res)) {
+ period_ns = res.tv_nsec + res.tv_sec * NSEC_IN_SEC;
+ *freq = period_ns * 1000; /* MHz */
+ }
+
+ 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 +1381,7 @@ 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_freq(opts->clockid, &opts->clockid_freq);

/* allow a "CLOCK_" prefix to the name */
if (!strncasecmp(str, "CLOCK_", 6))
@@ -1369,7 +1390,8 @@ 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_freq(opts->clockid,
+ &opts->clockid_freq);
}
}

diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 21bf7f5a3cf5..7f612f296b64 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_freq;
unsigned int proc_map_timeout;
};

diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 1f3ccc368530..ffb358f1ff1e 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_freq;
};

extern struct perf_env perf_env;
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 1ec1d9bc2d63..a37c40478b64 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1034,6 +1034,19 @@ static int write_auxtrace(struct feat_fd *ff,
return err;
}

+static int write_clockid(struct feat_fd *ff,
+ struct perf_evlist *evlist __maybe_unused)
+{
+ int ret;
+
+ ret = do_write(ff, &ff->ph->env.clockid_freq,
+ sizeof(ff->ph->env.clockid_freq));
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
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 +1521,11 @@ 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_freq);
+}
+
static void free_event_desc(struct perf_evsel *events)
{
struct perf_evsel *evsel;
@@ -2531,6 +2549,19 @@ 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_freq;
+
+ if (do_read_u64(ff, &clockid_freq))
+ return -1;
+
+ ff->ph->env.clockid_freq = clockid_freq;
+
+ 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 +2621,7 @@ 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,
};