Report minimum latency (#446)

* report minimum latency * remove unuse code, and package * add README.md about min value Co-authored-by: Tomás Senart <[email protected]>
tsenart · Jan 12, 2020 · 37da2b6 · 37da2b6
1 parent bd2bfbc
commit 37da2b6
Show file tree

Hide file tree

Showing 4 changed files with 12 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -406,7 +406,7 @@ Examples:
 ```console
 Requests      [total, rate, throughput] 1200, 120.00, 65.87
 Duration      [total, attack, wait]     10.094965987s, 9.949883921s, 145.082066ms
-Latencies     [mean, 50, 95, 99, max]   113.172398ms, 108.272568ms, 140.18235ms, 247.771566ms, 264.815246ms
+Latencies     [min, mean, 50, 95, 99, max]  90.438129ms, 113.172398ms, 108.272568ms, 140.18235ms, 247.771566ms, 264.815246ms
 Bytes In      [total, mean]             3714690, 3095.57
 Bytes Out     [total, mean]             0, 0.00
 Success       [ratio]                   55.42%
@@ -434,6 +434,7 @@ The `Duration` row shows:
 
 Latency is the amount of time taken for a response to a request to be read (including the `-max-body` bytes from the response body).
 
+- `min` is the minimum latency of all requests in an attack.
 - `mean` is the [arithmetic mean / average](https://en.wikipedia.org/wiki/Arithmetic_mean) of the latencies of all requests in an attack.
 - `50`, `90`, `95`, `99` are the 50th, 90th, 95th and 99th [percentiles](https://en.wikipedia.org/wiki/Percentile), respectively, of the latencies of all requests in an attack. To understand more about why these are useful, I recommend [this article](https://bravenewgeek.com/everything-you-know-about-latency-is-wrong/) from @tylertreat.
 - `max` is the maximum latency of all requests in an attack.
@@ -462,7 +463,8 @@ All duration like fields are in nanoseconds.
     "90th": 3228223,
     "95th": 3478629,
     "99th": 3530000,
-    "max": 3660505
+    "max": 3660505,
+    "min": 1949582
   },
   "buckets": {"0":9952,"1000000":40,"2000000":6,"3000000":0,"4000000":0,"5000000":2},
   "bytes_in": {

diff --git a/lib/metrics.go b/lib/metrics.go
@@ -144,6 +144,8 @@ type LatencyMetrics struct {
 	P99 time.Duration `json:"99th"`
 	// Max is the maximum observed request latency.
 	Max time.Duration `json:"max"`
+	// Min is the minimum observed request latency.
+	Min time.Duration `json:"min"`
 
 	estimator estimator
 }
@@ -154,6 +156,9 @@ func (l *LatencyMetrics) Add(latency time.Duration) {
 	if l.Total += latency; latency > l.Max {
 		l.Max = latency
 	}
+	if latency < l.Min || l.Min == 0 {
+		l.Min = latency
+	}
 	l.estimator.Add(float64(latency))
 }
 

diff --git a/lib/metrics_test.go b/lib/metrics_test.go
@@ -48,6 +48,7 @@ func TestMetrics_Add(t *testing.T) {
 			P95:       duration("9.5005ms"),
 			P99:       duration("9.9005ms"),
 			Max:       duration("10ms"),
+			Min:       duration("1us"),
 			estimator: got.Latencies.estimator,
 		},
 		BytesIn:     ByteMetrics{Total: 10240000, Mean: 1024},

diff --git a/lib/reporters.go b/lib/reporters.go
@@ -57,7 +57,7 @@ func NewHistogramReporter(h *Histogram) Reporter {
 func NewTextReporter(m *Metrics) Reporter {
 	const fmtstr = "Requests\t[total, rate, throughput]\t%d, %.2f, %.2f\n" +
 		"Duration\t[total, attack, wait]\t%s, %s, %s\n" +
-		"Latencies\t[mean, 50, 90, 95, 99, max]\t%s, %s, %s, %s, %s, %s\n" +
+		"Latencies\t[min, mean, 50, 90, 95, 99, max]\t%s, %s, %s, %s, %s, %s, %s\n" +
 		"Bytes In\t[total, mean]\t%d, %.2f\n" +
 		"Bytes Out\t[total, mean]\t%d, %.2f\n" +
 		"Success\t[ratio]\t%.2f%%\n" +
@@ -68,8 +68,7 @@ func NewTextReporter(m *Metrics) Reporter {
 		if _, err = fmt.Fprintf(tw, fmtstr,
 			m.Requests, m.Rate, m.Throughput,
 			m.Duration+m.Wait, m.Duration, m.Wait,
-			m.Latencies.Mean, m.Latencies.P50, m.Latencies.P90,
-			m.Latencies.P95, m.Latencies.P99, m.Latencies.Max,
+			m.Latencies.Min, m.Latencies.Mean, m.Latencies.P50, m.Latencies.P90, m.Latencies.P95, m.Latencies.P99, m.Latencies.Max,
 			m.BytesIn.Total, m.BytesIn.Mean,
 			m.BytesOut.Total, m.BytesOut.Mean,
 			m.Success*100,