cgo.go

package main

// void nothing() {}
import "C"
import "fmt"
import "testing"

func nothing() {}

func CNothing(b *testing.B) {
	for i := 0; i < b.N; i++ {
		C.nothing()
	}
}

func GoNothing(b *testing.B) {
	for i := 0; i < b.N; i++ {
		nothing()
	}
}

func main() {
	result := testing.Benchmark(CNothing)
	fmt.Println(result)
	result = testing.Benchmark(GoNothing)
	fmt.Println(result)
}

output

MacJames:bench jamesgray$ go build -gcflags=-N
MacJames:bench jamesgray$ ./bench
20000000	        82.7 ns/op
2000000000	         1.70 ns/op
MacJames:bench jamesgray$ ./bench
20000000	        82.9 ns/op
2000000000	         1.70 ns/op
MacJames:bench jamesgray$ go build -gcflags=
MacJames:bench jamesgray$ ./bench
20000000	        86.9 ns/op
2000000000	         0.42 ns/op
MacJames:bench jamesgray$ ./bench
20000000	        84.4 ns/op
2000000000	         0.43 ns/op