NuttX cpuload monitoring optimization

- Nuttx only process all suspend & resume scheduling notes when top is running, otherwise only track IDLE
 - convert cpuload and print load to c++
 - delete unused fields from print_load struct
 - update hrt_store_absolute_time (previous unused)

src/systemcmds/top/CMakeLists.txt

@@ -33,10 +33,11 @@
 px4_add_module(
 	MODULE systemcmds__top
 	MAIN top
+	STACK_MAIN 4096
 	PRIORITY
 		"SCHED_PRIORITY_MAX - 16" # max priority below high priority WQ threads
 	SRCS
-		top.c
+		top.cpp
 	DEPENDS
 		systemlib
 )

src/systemcmds/top/top.cpp

@@ -47,17 +47,11 @@
 #include <string.h>
 #include <poll.h>
 
-#include <systemlib/cpuload.h>
-#include <systemlib/printload.h>
+#include <px4_platform/cpuload.h>
+#include <px4_platform_common/printload.h>
 #include <drivers/drv_hrt.h>
 #include <px4_platform_common/module.h>
 
-/**
- * Start the top application.
- */
-__EXPORT int top_main(int argc, char *argv[]);
-
-
 static void print_usage(void)
 {
 	PRINT_MODULE_DESCRIPTION("Monitor running processes and their CPU, stack usage, priority and state");
@@ -66,32 +60,30 @@ static void print_usage(void)
 	PRINT_MODULE_USAGE_COMMAND_DESCR("once", "print load only once");
 }
 
-int
-top_main(int argc, char *argv[])
+extern "C" __EXPORT int top_main(int argc, char *argv[])
 {
-	hrt_abstime curr_time = hrt_absolute_time();
-
-	struct print_load_s load;
-	init_print_load_s(curr_time, &load);
+	print_load_s load{};
+	init_print_load(&load);
+	px4_usleep(200000);
 
 	/* clear screen */
 	dprintf(1, "\033[2J\n");
 
 	if (argc > 1) {
 		if (!strcmp(argv[1], "once")) {
-			print_load(curr_time, 1, &load);
 			px4_sleep(1);
-			print_load(hrt_absolute_time(), 1, &load);
+			print_load(STDOUT_FILENO, &load);
 
 		} else {
 			print_usage();
 		}
 
+		cpuload_monitor_stop();
 		return 0;
 	}
 
 	for (;;) {
-		print_load(curr_time, 1, &load);
+		print_load(STDOUT_FILENO, &load);
 
 		/* Sleep 200 ms waiting for user input five times ~ 1s */
 		for (int k = 0; k < 5; k++) {
@@ -108,6 +100,7 @@ top_main(int argc, char *argv[])
 				ret = read(0, &c, 1);
 
 				if (ret) {
+					cpuload_monitor_stop();
 					return 1;
 				}
 
@@ -116,6 +109,7 @@ top_main(int argc, char *argv[])
 				case 0x1b: // esc
 				case 'c':
 				case 'q':
+					cpuload_monitor_stop();
 					return 0;
 					/* not reached */
 				}
@@ -123,9 +117,8 @@ top_main(int argc, char *argv[])
 
 			px4_usleep(200000);
 		}
-
-		curr_time = hrt_absolute_time();
 	}
 
+	cpuload_monitor_stop();
 	return 0;
 }