[PATCH 1/1] cpupower: monitor: Show how a counter value is exported

[Hemanth Selam <hemanth.selam@gmail.com>]

"cpupower monitor -l" lists the name, the processor hierarchy level and
a description of every counter, but not how its value is exported. Some
counters are a percentage of the time spent in a state, others are
absolute values with their own unit, for example the Mperf "Freq"
counter reports MHz and the RAPL zones report micro Joule. Both cannot
be told apart from the listing.

Show the value type behind the hierarchy level and document it:

  [%]   The counter is a percentage of the time spent in the state.
  [abs] The counter is an absolute value, its unit depends on the
        counter, MHz for "Freq" or micro Joule for a RAPL zone.

Before:

  $ cpupower monitor -l
  Monitor "Mperf" (3 states) - Might overflow after 922000000 s
  C0	[T] -> Processor Core not idle
  Cx	[T] -> Processor Core in an idle state
  Freq	[T] -> Average Frequency (including boost) in MHz

After:

  $ cpupower monitor -l
  Monitor "Mperf" (3 states) - Might overflow after 922000000 s
  C0	[T] [%] -> Processor Core not idle
  Cx	[T] [%] -> Processor Core in an idle state
  Freq	[T] [abs] -> Average Frequency (including boost) in MHz

The time granularity part of the ToDo needs a new cstate_t member every
monitor has to fill in, keep it noted.

Signed-off-by: Hemanth Selam <hemanth.selam@gmail.com>
---
 tools/power/cpupower/man/cpupower-monitor.1   |  8 +++++++
 .../utils/idle_monitor/cpupower-monitor.c     | 22 ++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/tools/power/cpupower/man/cpupower-monitor.1 b/tools/power/cpupower/man/cpupower-monitor.1
index 89af019f8dc4..c8008919627c 100644
--- a/tools/power/cpupower/man/cpupower-monitor.1
+++ b/tools/power/cpupower/man/cpupower-monitor.1
@@ -51,6 +51,14 @@ coverage in square brackets:
 .IP \(bu
 [M] \-> Machine/Platform wide counter
 .RE
+.IP \(bu
+How the counter is exported, in square brackets behind the hierarchy level:
+.RS 4
+.IP \(bu
+[%] \-> Percentage of the time spent in the state
+.IP \(bu
+[abs] \-> Absolute value, the unit depends on the counter
+.RE
 .RE
 .RE
 .PP
diff --git a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
index e8b3841d5c0f..376a1e30653a 100644
--- a/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c
@@ -269,6 +269,20 @@ static void parse_monitor_param(char *param)
 	avail_monitors = hits;
 }
 
+/*
+ * A monitor exports a counter either as a percentage of the time spent
+ * in the state or as an absolute value. Tell both apart, so that the
+ * numbers a measurement run prints can be interpreted.
+ */
+static const char *value_abbr(const cstate_t *state)
+{
+	if (state->get_count_percent)
+		return "%";
+	if (state->get_count)
+		return "abs";
+	return "?";
+}
+
 void list_monitors(void)
 {
 	unsigned int mon;
@@ -284,10 +298,12 @@ void list_monitors(void)
 		for (state = 0; state < monitors[mon]->hw_states_num; state++) {
 			s = monitors[mon]->hw_states[state];
 			/*
-			 * ToDo show more state capabilities:
-			 * percent, time (granlarity)
+			 * ToDo show the time granularity of a counter, this
+			 * needs a new cstate_t member every monitor has to
+			 * fill in.
 			 */
-			printf("%s\t[%c] -> %s\n", s.name, range_abbr[s.range],
+			printf("%s\t[%c] [%s] -> %s\n", s.name,
+			       range_abbr[s.range], value_abbr(&s),
 			       gettext(s.desc));
 		}
 	}
-- 
2.43.7