stats: Add basic schedule-miss stats to needle

In camelback (48b6894ef41e9a06ccbb696d062d86ef60dc2c4b) we have
a much more comprehensive system for recording
schedule misses because it has a 'stats' map. This is much more basic
and just writes the last event into cmap. You can still query and track
the value though.

Signed-off-by: Christine Caulfield <ccaulfie@redhat.com>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>

exec/main.c

@@ -852,6 +852,9 @@ static void timer_function_scheduler_timeout (void *data)
 		log_printf (LOGSYS_LEVEL_WARNING, "Corosync main process was not scheduled for %0.4f ms "
 		    "(threshold is %0.4f ms). Consider token timeout increase.",
 		    (float)tv_diff / QB_TIME_NS_IN_MSEC, (float)timeout_data->max_tv_diff / QB_TIME_NS_IN_MSEC);
+
+		icmap_set_float("runtime.schedmiss.delay", (float)tv_diff / QB_TIME_NS_IN_MSEC);
+		icmap_set_uint64("runtime.schedmiss.timestamp", qb_util_nano_from_epoch_get() / QB_TIME_NS_IN_MSEC);
 	}
 
 	/*

man/cmap_keys.8

@@ -255,6 +255,16 @@ Status of the processor. Can be one of joined and left.
 .B config_version
 Config version of the member node.
 
+.TP
+runtime.schedmiss.timestamp
+The timestamp of the last time when corosync failed to be scheduled
+for the required amount of time. The even is warned in syslog but this
+is easier to find. The time is milli-seconds since the epoch.
+
+.B
+runtime.schedmiss.delay
+The amount of time (milliseconds as a float) that corosync was delayed.
+
 .TP
 resources.process.PID.*
 Prefix created by applications using SAM with CMAP integration.