dmstats: add 'interval' and 'interval_ns' report fieldsdev-bmr-dmstats-columns

Add a pair of fields to expose the current per-interval duation
estimate. The 'interval' field provides a real value in units of
seconds and the 'interval_ns' field provides the same quantity
expressed as a whole number of nanoseconds.

2 files changed, 49 insertions, 0 deletions

diff --git a/man/dmstats.8.in b/man/dmstats.8.in
index 3b9f03222..f8d294980 100644
--- a/man/dmstats.8.in
+++ b/man/dmstats.8.in
@@ -501,6 +501,20 @@ The program ID value associated with this region.
 .br
 The auxiliary data value associated with this region.
 .br
+.HP
+.B interval_ns
+.br
+The estimated interval over which the current counter values have
+accumulated. The vaulue is reported as an interger expressed in units
+of nanoseconds.
+.br
+.HP
+.B interval
+.br
+The estimated interval over which the current counter values have
+accumulated. The value is reported as a real number in units of
+seconds.
+.br
 .SS Basic counters
 Basic counters provide access to the raw counter data from the kernel,
 allowing further processing to be carried out by another program.
diff --git a/tools/dmsetup.c b/tools/dmsetup.c
index 1dcc7e3b8..b270cfd01 100644
--- a/tools/dmsetup.c
+++ b/tools/dmsetup.c
@@ -3325,6 +3325,15 @@ static int _dm_stats_program_id_disp(struct dm_report *rh,
 	return dm_report_field_string(rh, field, (const char * const*) &program_id);
 }
 
+static int _dm_stats_sample_interval_ns_disp(struct dm_report *rh,
+					     struct dm_pool *mem __attribute__((unused)),
+					     struct dm_report_field *field, const void *data,
+					     void *private __attribute__((unused)))
+{
+	/* FIXME: use internal interval estimate when supported by libdm */
+	return dm_report_field_uint64(rh, field, &_last_interval);
+}
+
 static int _dm_stats_aux_data_disp(struct dm_report *rh,
 				     struct dm_pool *mem __attribute__((unused)),
 				     struct dm_report_field *field, const void *data,
@@ -3337,6 +3346,30 @@ static int _dm_stats_aux_data_disp(struct dm_report *rh,
 	return dm_report_field_string(rh, field, (const char * const*) &aux_data);
 }
 
+static int _dm_stats_sample_interval_disp(struct dm_report *rh,
+					  struct dm_pool *mem __attribute__((unused)),
+					  struct dm_report_field *field, const void *data,
+					  void *private __attribute__((unused)))
+{
+	char buf[64];
+	char *repstr;
+	double *sortval;
+
+	if (!(sortval = dm_pool_alloc(mem, sizeof(*sortval))))
+		return_0;
+
+	*sortval = (double)_last_interval / (double) NSEC_PER_SEC;
+
+	if (!dm_snprintf(buf, sizeof(buf), "%2.6f", *sortval))
+		return_0;
+
+	if (!(repstr = dm_pool_strdup(mem, buf)))
+		return_0;
+
+	dm_report_field_set_value(field, repstr, sortval);
+	return 1;
+}
+
 static int _dm_stats_rrqm_disp(struct dm_report *rh,
 			       struct dm_pool *mem __attribute__((unused)),
 			       struct dm_report_field *field, const void *data,
@@ -3878,6 +3911,8 @@ FIELD_F(STATS, SIZ, "ASize", 5, dm_stats_area_len, "area_len", "Area length.")
 FIELD_F(STATS, NUM, "#Areas", 6, dm_stats_area_count, "area_count", "Area count.")
 FIELD_F(STATS, STR, "ProgID", 6, dm_stats_program_id, "program_id", "Program ID.")
 FIELD_F(STATS, STR, "AuxDat", 6, dm_stats_aux_data, "aux_data", "Auxiliary data.")
+FIELD_F(STATS, NUM, "IntervalNSec", 10, dm_stats_sample_interval_ns, "interval_ns", "Sampling interval in nanoseconds.")
+FIELD_F(STATS, NUM, "Interval", 8, dm_stats_sample_interval, "interval", "Sampling interval.")
 
 /* Stats derived metrics */
 FIELD_F(STATS, NUM, "RRqM/s", 8, dm_stats_rrqm, "rrqm", "Read requests merged per second.")