added warmup phase to histogram for better selection of min/max (closes #12)

include/villas/hist.h

@@ -47,6 +47,8 @@ struct hist {
 	int length;		/**< The number of buckets in #data. */
 
 	hist_cnt_t total;	/**< Total number of counted values. */
+	hist_cnt_t warmup;	/**< Number of values which are used during warmup phase. */
+
 	hist_cnt_t higher;	/**< The number of values which are higher than #high. */
 	hist_cnt_t lower;	/**< The number of values which are lower than #low. */
 
@@ -56,7 +58,7 @@ struct hist {
 };
 
 /** Initialize struct hist with supplied values and allocate memory for buckets. */
-int hist_init(struct hist *h, double start, double end, double resolution);
+int hist_init(struct hist *h, int buckets, hist_cnt_t warmup);
 
 /** Free the dynamically allocated memory. */
 int hist_destroy(struct hist *h);

include/villas/stats.h

@@ -66,7 +66,7 @@ struct stats {
 	struct stats_delta *delta;
 };
 
-int stats_init(struct stats *s);
+int stats_init(struct stats *s, int buckets, int warmup);
 
 void stats_destroy(struct stats *s);
 

lib/hist.c

@@ -34,20 +34,12 @@
 #define VAL(h, i)	((h)->low + (i) * (h)->resolution)
 #define INDEX(h, v)	round((v - (h)->low) / (h)->resolution)
 
-int hist_init(struct hist *h, double low, double high, double resolution)
+int hist_init(struct hist *h, int buckets, hist_cnt_t warmup)
 {
-	h->low = low;
-	h->high = high;
-	h->resolution = resolution;
+	h->length = buckets;
+	h->warmup = warmup;
 
-	if (resolution > 0) {
-		h->length = (high - low) / resolution;
-		h->data = alloc(h->length * sizeof(hist_cnt_t));
-	}
-	else {
-		h->length = 0;
-		h->data = NULL;
-	}
+	h->data = buckets ? alloc(h->length * sizeof(hist_cnt_t)) : NULL;
 
 	hist_reset(h);
 
@@ -66,8 +58,6 @@ int hist_destroy(struct hist *h)
 
 void hist_put(struct hist *h, double value)
 {
-	int idx = INDEX(h, value);
-
 	h->last = value;
 
 	/* Update min/max */
@@ -76,13 +66,25 @@ void hist_put(struct hist *h, double value)
 	if (value < h->lowest)
 		h->lowest = value;
 
-	/* Check bounds and increment */
-	if      (idx >= h->length)
-		h->higher++;
-	else if (idx < 0)
-		h->lower++;
-	else if (h->data != NULL)
-		h->data[idx]++;
+	if (h->total < h->warmup) {
+
+	}
+	else if (h->total == h->warmup) {
+		h->low  = hist_mean(h) - 3 * hist_stddev(h);
+		h->high = hist_mean(h) + 3 * hist_stddev(h);
+		h->resolution = (h->high - h->low) / h->length;
+	}
+	else {
+		int idx = INDEX(h, value);
+
+		/* Check bounds and increment */
+		if      (idx >= h->length)
+			h->higher++;
+		else if (idx < 0)
+			h->lower++;
+		else if (h->data != NULL)
+			h->data[idx]++;
+	}
 
 	h->total++;
 

lib/hooks/stats_collect.c

@@ -34,6 +34,8 @@ struct stats_collect {
 
 	enum stats_format format;
 	int verbose;
+	int warmup;
+	int buckets;
 
 	FILE *output;
 	const char *uri;
@@ -43,8 +45,6 @@ static int stats_collect_init(struct hook *h)
 {
 	struct stats_collect *p = h->_vd;
 
-	stats_init(&p->stats);
-
 	/* Register statistic object to path.
 	 *
 	 * This allows the path code to update statistics. */
@@ -54,6 +54,8 @@ static int stats_collect_init(struct hook *h)
 	/* Set default values */
 	p->format = STATS_FORMAT_HUMAN;
 	p->verbose = 0;
+	p->warmup = 500;
+	p->buckets = 20;
 	p->uri = NULL;
 	p->output = stdout;
 
@@ -73,6 +75,8 @@ static int stats_collect_start(struct hook *h)
 {
 	struct stats_collect *p = h->_vd;
 
+	stats_init(&p->stats, p->buckets, p->warmup);
+
 	if (p->uri) {
 		p->output = fopen(p->uri, "w+");
 		if (!p->output)
@@ -129,6 +133,8 @@ static int stats_collect_parse(struct hook *h, config_setting_t *cfg)
 	}
 
 	config_setting_lookup_int(cfg, "verbose", &p->verbose);
+	config_setting_lookup_int(cfg, "warmup", &p->warmup);
+	config_setting_lookup_int(cfg, "buckets", &p->buckets);
 	config_setting_lookup_string(cfg, "output", &p->uri);
 
 	return 0;
@@ -164,4 +170,4 @@ static struct plugin p = {
 
 REGISTER_PLUGIN(&p)
 
-/** @} */
+/** @} */

lib/stats.c

@@ -33,26 +33,19 @@ static struct stats_desc {
 	const char *name;
 	const char *unit;
 	const char *desc;
-	struct {
-		double min;
-		double max;
-		double resolution;
-	} hist;
+	int hist_buckets;
 } stats_table[] = {
-	{ "skipped",	  "samples",	"skipped samples by hooks",						{0,	0,	-1,	}},
-	{ "reorderd",	  "samples",	"reordered samples",							{0,	20,	1,	}},
-	{ "gap_sequence", "samples",	"sequence number displacement of received messages",			{-10,	10, 20,		}},
-	{ "gap_sample",	  "seconds",	"inter message timestamps (as sent by remote)",				{90e-3,	110e-3,	1e-3,	}},
-	{ "gap_received", "seconds",	"Histogram for inter message arrival time (as seen by this instance)",	{90e-3,	110e-3,	1e-3,	}},
-	{ "owd",	  "seconds",	"Histogram for one-way-delay (OWD) of received messages",		{0,	1,	100e-3,	}}
+	{ "skipped",	  "samples",	"skipped samples by hooks",						25 },
+	{ "reorderd",	  "samples",	"reordered samples",							25 },
+	{ "gap_sample",	  "seconds",	"inter message timestamps (as sent by remote)",				25 },
+	{ "gap_received", "seconds",	"Histogram for inter message arrival time (as seen by this instance)",	25 },
+	{ "owd",	  "seconds",	"Histogram for one-way-delay (OWD) of received messages",		25 }
 };
 
-int stats_init(struct stats *s)
+int stats_init(struct stats *s, int buckets, int warmup)
 {
-	for (int i = 0; i < STATS_COUNT; i++) {
-		struct stats_desc *desc = &stats_table[i];
-		hist_init(&s->histograms[i], desc->hist.min, desc->hist.max, desc->hist.resolution);
-	}
+	for (int i = 0; i < STATS_COUNT; i++)
+		hist_init(&s->histograms[i], buckets, warmup);
 
 	s->delta = alloc(sizeof(struct stats_delta));
 
@@ -245,4 +238,4 @@ enum stats_id stats_lookup_id(const char *name)
 	}
 
 	return -1;
-}
+}

src/test-rtt.c

@@ -43,6 +43,9 @@ static struct node *node;
 static int running = 1; 	/**< Initiate shutdown if zero */
 static int count =  -1;		/**< Amount of messages which should be sent (default: -1 for unlimited) */
 
+static hist_cnt_t hist_warmup;
+static int hist_buckets;
+
 /** File descriptor for Matlab results.
  * This allows you to write Matlab results in a seperate log file:
  *
@@ -50,11 +53,6 @@ static int count =  -1;		/**< Amount of messages which should be sent (default:
  */
 static int fd = STDOUT_FILENO;
 
-/* Histogram */
-static double low = 0;		/**< Lowest value in histogram. */
-static double high = 2e-4;	/**< Highest value in histogram. */
-static double res = 1e-5;	/**< Histogram resolution. */
-
 #define CLOCK_ID	CLOCK_MONOTONIC
 
 /* Prototypes */
@@ -73,9 +71,8 @@ void usage()
 	printf("  OPTIONS is one or more of the following options:\n");
 	printf("    -c CNT  send CNT messages\n");
 	printf("    -f FD   use file descriptor FD for result output instead of stdout\n");
-	printf("    -l LOW  smallest value for histogram\n");
-	printf("    -H HIGH largest value for histogram\n");
-	printf("    -r RES  bucket resolution for histogram\n");
+	printf("    -b BKTS number of buckets for histogram\n");
+	printf("    -w WMUP duration of histogram warmup phase\n");
 	printf("    -h      show this usage information\n");
 	printf("\n");
 
@@ -86,7 +83,7 @@ int main(int argc, char *argv[])
 {
 	/* Parse Arguments */
 	char c, *endptr;
-	while ((c = getopt (argc, argv, "l:hH:r:f:c:")) != -1) {
+	while ((c = getopt (argc, argv, "w:h:r:f:c:b:")) != -1) {
 		switch (c) {
 			case 'c':
 				count = strtoul(optarg, &endptr, 10);
@@ -94,14 +91,11 @@ int main(int argc, char *argv[])
 			case 'f':
 				fd = strtoul(optarg, &endptr, 10);
 				goto check;
-			case 'l':
-				low = strtod(optarg, &endptr);
+			case 'w':
+				hist_warmup = strtoul(optarg, &endptr, 10);
 				goto check;
-			case 'H':
-				high = strtod(optarg, &endptr);
-				goto check;
-			case 'r':
-				res = strtod(optarg, &endptr);
+			case 'b':
+				hist_buckets = strtoul(optarg, &endptr, 10);
 				goto check;
 			case 'h':
 			case '?':
@@ -157,7 +151,7 @@ void test_rtt() {
 	struct sample *smp_send = alloc(SAMPLE_LEN(2));
 	struct sample *smp_recv = alloc(SAMPLE_LEN(2));
 
-	hist_init(&hist, low, high, res);
+	hist_init(&hist, 20, 100);
 
 	/* Print header */
 	fprintf(stdout, "%17s%5s%10s%10s%10s%10s%10s\n", "timestamp", "seq", "rtt", "min", "max", "mean", "stddev");