modules/stats: 10-100-1000 ms latency tracking

modules/stats/README.rst

@@ -79,5 +79,9 @@ Built-in statistics
 * ``answer.noerror`` - number of **NOERROR** answers
 * ``answer.nxdomain`` - number of **NXDOMAIN** answers
 * ``answer.servfail`` - number of **SERVFAIL** answers
+* ``answer.10ms`` - number of answers completed in 10ms
+* ``answer.100ms`` - number of answers completed in 100ms
+* ``answer.1000ms`` - number of answers completed in 1000ms
+* ``answer.slow`` - number of answers that took more than 1000ms
 * ``query.edns`` - number of queries with EDNS
 * ``query.dnssec`` - number of queries with DNSSEC DO=1

modules/stats/stats.c

@@ -43,7 +43,7 @@
 /** @cond internal Fixed-size map of predefined metrics. */
 #define CONST_METRICS(X) \
 	X(answer,total) X(answer,noerror) X(answer,nxdomain) X(answer,servfail) \
-	X(answer,cached) X(answer,slow) \
+	X(answer,cached) X(answer,10ms) X(answer,100ms) X(answer,1000ms) X(answer,slow) \
 	X(query,edns) X(query,dnssec) \
 	X(const,end)
 
@@ -82,13 +82,6 @@ float time_diff(struct timeval *begin, struct timeval *end)
 
 }
 
-/** @internal Add to map counter */
-static inline void stat_add(struct stat_data *data, const char *key, ssize_t incr)
-{
-	void *val = map_get(&data->map, key);
-	map_set(&data->map, key, (void *)((size_t)val + incr));
-}
-
 /** @internal Add to const map counter */
 static inline void stat_const_add(struct stat_data *data, enum const_metric key, ssize_t incr)
 {
@@ -161,12 +154,18 @@ static int collect(knot_layer_t *ctx)
 		if (last->flags & QUERY_CACHED) {
 			stat_const_add(data, metric_answer_cached, 1);
 		}
-		/* Count slow queries (>1000ms) */
+		/* Histogram of answer latency. */
 		struct kr_query *first = HEAD(rplan->resolved);
 		struct timeval now;
 		gettimeofday(&now, NULL);
 		float elapsed = time_diff(&first->timestamp, &now);
-		if (elapsed > 1000.0) {
+		if (elapsed < 10.0) {
+			stat_const_add(data, metric_answer_10ms, 1);
+		} else if (elapsed < 100.0) {
+			stat_const_add(data, metric_answer_100ms, 1);
+		} else if (elapsed < 1000.0) {
+			stat_const_add(data, metric_answer_1000ms, 1);
+		} else {
 			stat_const_add(data, metric_answer_slow, 1);
 		}
 	}