canbusload: support busload visualization

Add '-v' option for visualize busload, the output shows a moving
histogram of the past 90 seconds.

canbusload 2024-09-23 17:19:33 (exact bitstuffing)
 can0@500k   487   55558   31048       0  99% |XXXXXXXXXXXXXXXXXXX.|
100%|..........................................................................................
 95%|..............................................................................XXXXXXXXXXXX
 90%|.............................................................................XXXXXXXXXXXXX
 85%|.............................................................................XXXXXXXXXXXXX
 80%|.............................................................................XXXXXXXXXXXXX
 75%|.............................................................................XXXXXXXXXXXXX
 70%|.............................................................................XXXXXXXXXXXXX
 65%|.............................................................................XXXXXXXXXXXXX
 60%|............................................................................XXXXXXXXXXXXXX
 55%|............................................................................XXXXXXXXXXXXXX
 50%|............................................................................XXXXXXXXXXXXXX
 45%|............................................................................XXXXXXXXXXXXXX
 40%|............................................................................XXXXXXXXXXXXXX
 35%|.........................................XXX................................XXXXXXXXXXXXXX
 30%|.........................................XXXX...............................XXXXXXXXXXXXXX
 25%|........................................XXXXXX.............................XXXXXXXXXXXXXXX
 20%|XXXXXXXX...............................XXXXXXXXXXXXXXXXX....XXXXXXXXXXX...XXXXXXXXXXXXXXXX
 15%|XXXXXXXXX.............................XXXXXXXXXXXXXXXXXXXX.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 10%|XXXXXXXXX.XXXXXXXXXXXXXXXXXXX..XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
  5%|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Signed-off-by: Zhu Yi <yi.zhu5@cn.bosch.com>
Signed-off-by: Hubert Streidl <hubert.streidl@de.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Link: https://lore.kernel.org/r/20250120162332.19157-3-mark.jonas@de.bosch.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

canbusload.c

@@ -74,6 +74,7 @@
 #define PERCENTRES 5 /* resolution in percent for bargraph */
 #define NUMBAR (100 / PERCENTRES) /* number of bargraph elements */
 #define BRSTRLEN 20
+#define VISUAL_WINDOW 90 /* window width for visualization */
 
 /*
  * Inspired from
@@ -111,19 +112,22 @@ static struct {
 	unsigned int load_1m;
 	unsigned int load_5m;
 	unsigned int load_15m;
+	unsigned int loads[VISUAL_WINDOW];
+	unsigned int index;
 } stat[MAXDEVS + 1];
 
 static volatile int running = 1;
 static volatile sig_atomic_t signal_num;
 static int max_devname_len; /* to prevent frazzled device name output */
 static int max_bitratestr_len;
-static int currmax;
+static unsigned int currmax;
 static unsigned char redraw;
 static unsigned char timestamp;
 static unsigned char color;
 static unsigned char bargraph;
 static bool statistic;
 static bool reset;
+static bool visualize;
 static enum cfl_mode mode = CFL_WORSTCASE;
 static char *prg;
 static struct termios old;
@@ -141,6 +145,7 @@ static void print_usage(char *prg)
 	fprintf(stderr, "         -i  (ignore bitstuffing in bandwidth calculation)\n");
 	fprintf(stderr, "         -e  (exact calculation of stuffed bits)\n");
 	fprintf(stderr, "         -s  (show statistics, press 'r' to reset)\n");
+	fprintf(stderr, "         -v  (show busload visualization)\n");
 	fprintf(stderr, "\n");
 	fprintf(stderr, "Up to %d CAN interfaces with mandatory bitrate can be specified on the \n", MAXDEVS);
 	fprintf(stderr, "commandline in the form: <ifname>@<bitrate>[,<dbitrate>]\n");
@@ -203,7 +208,7 @@ static unsigned int calc_load(unsigned int load_fp,
 
 static void printstats(int signo)
 {
-	int i, j, percent;
+	unsigned int i, j, k, percent, index;
 
 	if (redraw)
 		printf("%s", CSR_HOME);
@@ -315,6 +320,28 @@ static void printstats(int signo)
 			printf("|");
 		}
 
+		if (visualize) {
+			stat[i].loads[stat[i].index] = percent;
+			stat[i].index = (stat[i].index + 1) % VISUAL_WINDOW;
+
+			printf("\n");
+			for (j = 0; j < NUMBAR; j++) {
+				printf("%3d%%|", (NUMBAR - j) * PERCENTRES);
+				index = stat[i].index;
+				for (k = 0; k < VISUAL_WINDOW; k++) {
+					percent = stat[i].loads[index];
+
+					if ((percent / PERCENTRES) >= (NUMBAR - j))
+						printf("X");
+					else
+						printf(".");
+
+					index = (index + 1) % VISUAL_WINDOW;
+				}
+				printf("\n");
+			}
+		}
+
 		if (color)
 			printf("%s", ATTRESET);
 
@@ -353,7 +380,8 @@ int main(int argc, char **argv)
 	struct canfd_frame frame;
 	struct iovec iov;
 	struct msghdr msg;
-	int nbytes, i;
+	unsigned int i;
+	int nbytes;
 
 	int have_anydev = 0;
 	unsigned int anydev_bitrate = 0;
@@ -375,7 +403,7 @@ int main(int argc, char **argv)
 
 	prg = basename(argv[0]);
 
-	while ((opt = getopt(argc, argv, "rtbciesh?")) != -1) {
+	while ((opt = getopt(argc, argv, "rtbciesvh?")) != -1) {
 		switch (opt) {
 		case 'r':
 			redraw = 1;
@@ -406,6 +434,10 @@ int main(int argc, char **argv)
 			reset = true;
 			break;
 
+		case 'v':
+			visualize = true;
+			break;
+
 		default:
 			print_usage(prg);
 			exit(1);