rt-app: introduce cumulative_slack global option

It might be useful, for phases that contains multiple timer events, to
accumulate intermediate slack and report this number once the phase
completes. Implement such behaviour and introduce a global option to
select between current behaivour and the new one.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

4 files changed, 20 insertions, 4 deletions

diff --git a/doc/tutorial.txt b/doc/tutorial.txt
index a4455b6..54488a0 100644
--- a/doc/tutorial.txt
+++ b/doc/tutorial.txt
@@ -137,6 +137,10 @@ Default value is "/dev/null".
 used to create IO-bounded and memory-bounded busy loop. Default value is
 4194304(4MB).
 
+* cumulative_slack : Boolean. Accumulate slack (see below) measured during
+  successive timer events in a phase. Default value is False (time between the
+  end of last event and the end of the phase).
+
 *** default global object:
 	"global" : {
 		"duration" : -1,
@@ -150,7 +154,8 @@ used to create IO-bounded and memory-bounded busy loop. Default value is
 		"ftrace" : false,
 		"gnuplot" : false,
 		"io_device" : "/dev/null"
-		"mem_buffer_size" : 4194304
+		"mem_buffer_size" : 4194304,
+		"cumulative_slack" : false
 	}
 
 **** tasks object ****
@@ -499,8 +504,8 @@ metrics are:
 - start/end : absolute start and end time of a phase. Same time base is used in
   ftrace
 - rel_st: start time of a phase relatively to the beg of the use case
-- slack: for periodic phases (phases that ends with a timer), time between the
-  end of last event and the end of the phase, e.g.
+- slack: if global option "cumulative_slack" (see above) is false, time between
+  the end of last event and the end of the phase, e.g.
 
   taskA ...|-- run5 --|- sleep5 -|-- run5--|..timer20.|-- run5 --|- sleep5 -|-- run6 --|.timer20.|
             <--------------- period 20 --------------> <--------------- period 20 -------------->
@@ -513,6 +518,10 @@ metrics are:
             <--------------- period 20 -------------->
                                                        <slack-5>
 
+  if global option "cumulative_slack" is true, all the intermediate slacks of a
+  phase with multiple timers are accumulated and reported when the phase
+  completes
+
 - c_duration: sum of the configured duration of run/runtime events
 - c_period: sum of the timer(s) period(s)
 - wu_lat: sum of wakeup latencies after timer events
diff --git a/src/rt-app.c b/src/rt-app.c
index fb4b37d..a7a1eb4 100644
--- a/src/rt-app.c
+++ b/src/rt-app.c
@@ -332,7 +332,10 @@ static int run_event(event_data_t *event, int dry_run,
 			rdata->res.timer.t_next = timespec_add(&rdata->res.timer.t_next, &t_period);
 			clock_gettime(CLOCK_MONOTONIC, &t_now);
 			t_slack = timespec_sub(&rdata->res.timer.t_next, &t_now);
-			ldata->slack = timespec_to_usec_long(&t_slack);
+			if (opts.cumulative_slack)
+				ldata->slack += timespec_to_usec_long(&t_slack);
+			else
+				ldata->slack = timespec_to_usec_long(&t_slack);
 			if (timespec_lower(&t_now, &rdata->res.timer.t_next)) {
 				clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &rdata->res.timer.t_next, NULL);
 				clock_gettime(CLOCK_MONOTONIC, &t_now);
diff --git a/src/rt-app_parse_config.c b/src/rt-app_parse_config.c
index fbc4612..2b27f64 100644
--- a/src/rt-app_parse_config.c
+++ b/src/rt-app_parse_config.c
@@ -784,6 +784,7 @@ parse_global(struct json_object *global, rtapp_options_t *opts)
 		opts->pi_enabled = 0;
 		opts->io_device = strdup("/dev/null");
 		opts->mem_buffer_size = DEFAULT_MEM_BUF_SIZE;
+		opts->cumulative_slack = 0;
 		return;
 	}
 
@@ -872,6 +873,7 @@ parse_global(struct json_object *global, rtapp_options_t *opts)
 						"/dev/null");
 	opts->mem_buffer_size = get_int_value_from(global, "mem_buffer_size",
 							TRUE, DEFAULT_MEM_BUF_SIZE);
+	opts->cumulative_slack = get_bool_value_from(global, "cumulative_slack", TRUE, 0);
 
 }
 
diff --git a/src/rt-app_types.h b/src/rt-app_types.h
index 718ce77..1eb9467 100644
--- a/src/rt-app_types.h
+++ b/src/rt-app_types.h
@@ -196,6 +196,8 @@ typedef struct _rtapp_options_t {
 	int die_on_dmiss;
 	int mem_buffer_size;
 	char *io_device;
+
+	int cumulative_slack;
 } rtapp_options_t;
 
 typedef struct _timing_point_t {