fmt: benchmark floating point.

mallocs per Sprintf("%x"): 1
mallocs per Sprintf("%g"): 4

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5449106

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index d42a8fe1f2912846cec9068a2a0f583278fd12b4..63c33380a25a307a60ef93752bfa402a1510259c 100644 (file)
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -500,69 +500,84 @@ func BenchmarkSprintfPrefixedInt(b *testing.B) {
        }
 }
 
+func BenchmarkSprintfFloat(b *testing.B) {
+       for i := 0; i < b.N; i++ {
+               Sprintf("%g", 5.23184)
+       }
+}
+
 func TestCountMallocs(t *testing.T) {
        if testing.Short() {
                return
        }
+       const N = 100
        runtime.UpdateMemStats()
        mallocs := 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                Sprintf("")
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Sprintf(\"\"): %d\n", mallocs/100)
+       Printf("mallocs per Sprintf(\"\"): %d\n", mallocs/N)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                Sprintf("xxx")
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Sprintf(\"xxx\"): %d\n", mallocs/100)
+       Printf("mallocs per Sprintf(\"xxx\"): %d\n", mallocs/N)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                Sprintf("%x", i)
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Sprintf(\"%%x\"): %d\n", mallocs/100)
+       Printf("mallocs per Sprintf(\"%%x\"): %d\n", mallocs/N)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                Sprintf("%s", "hello")
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Sprintf(\"%%s\"): %d\n", mallocs/100)
+       Printf("mallocs per Sprintf(\"%%s\"): %d\n", mallocs/N)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                Sprintf("%x %x", i, i)
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Sprintf(\"%%x %%x\"): %d\n", mallocs/100)
+       Printf("mallocs per Sprintf(\"%%x %%x\"): %d\n", mallocs/N)
+       runtime.UpdateMemStats()
+       mallocs = 0 - runtime.MemStats.Mallocs
+       for i := 0; i < N; i++ {
+               Sprintf("%g", 3.14159)
+       }
+       runtime.UpdateMemStats()
+       mallocs += runtime.MemStats.Mallocs
+       Printf("mallocs per Sprintf(\"%%g\"): %d\n", mallocs/N)
        buf := new(bytes.Buffer)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                buf.Reset()
                Fprintf(buf, "%x %x %x", i, i, i)
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Fprintf(buf, \"%%x %%x %%x\"): %d\n", mallocs/100)
+       Printf("mallocs per Fprintf(buf, \"%%x %%x %%x\"): %d\n", mallocs/N)
        runtime.UpdateMemStats()
        mallocs = 0 - runtime.MemStats.Mallocs
-       for i := 0; i < 100; i++ {
+       for i := 0; i < N; i++ {
                buf.Reset()
                Fprintf(buf, "%s", "hello")
        }
        runtime.UpdateMemStats()
        mallocs += runtime.MemStats.Mallocs
-       Printf("mallocs per Fprintf(buf, \"%%s\"): %d\n", mallocs/100)
+       Printf("mallocs per Fprintf(buf, \"%%s\"): %d\n", mallocs/N)
 }
 
 type flagPrinter struct{}