1 files changed, 46 insertions, 7 deletions
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index ca0cdbb7c9..db28497e39 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -1502,19 +1502,58 @@ var makeFieldsInput = func() []byte {
 	return x
 }
 
-var fieldsInput = makeFieldsInput()
+var makeFieldsInputASCII = func() []byte {
+	x := make([]byte, 1<<20)
+	// Input is ~10% space, rest ASCII non-space.
+	for i := range x {
+		if rand.Intn(10) == 0 {
+			x[i] = ' '
+		} else {
+			x[i] = 'x'
+		}
+	}
+	return x
+}
+
+var bytesdata = []struct {
+	name string
+	data []byte
+}{
+	{"ASCII", makeFieldsInputASCII()},
+	{"Mixed", makeFieldsInput()},
+}
 
 func BenchmarkFields(b *testing.B) {
-	b.SetBytes(int64(len(fieldsInput)))
-	for i := 0; i < b.N; i++ {
-		Fields(fieldsInput)
+	for _, sd := range bytesdata {
+		b.Run(sd.name, func(b *testing.B) {
+			for j := 1 << 4; j <= 1<<20; j <<= 4 {
+				b.Run(fmt.Sprintf("%d", j), func(b *testing.B) {
+					b.ReportAllocs()
+					b.SetBytes(int64(j))
+					data := sd.data[:j]
+					for i := 0; i < b.N; i++ {
+						Fields(data)
+					}
+				})
+			}
+		})
 	}
 }
 
 func BenchmarkFieldsFunc(b *testing.B) {
-	b.SetBytes(int64(len(fieldsInput)))
-	for i := 0; i < b.N; i++ {
-		FieldsFunc(fieldsInput, unicode.IsSpace)
+	for _, sd := range bytesdata {
+		b.Run(sd.name, func(b *testing.B) {
+			for j := 1 << 4; j <= 1<<20; j <<= 4 {
+				b.Run(fmt.Sprintf("%d", j), func(b *testing.B) {
+					b.ReportAllocs()
+					b.SetBytes(int64(j))
+					data := sd.data[:j]
+					for i := 0; i < b.N; i++ {
+						FieldsFunc(data, unicode.IsSpace)
+					}
+				})
+			}
+		})
 	}
 }