On point [3], using the Shane's code, and with an additional one for gccgo, on my laptop I see:
$ go-11 test -cpu=1,2,4,8,16 -bench Cgo
goos: linux
goarch: amd64
pkg: github.com/shanemhansen/cgobench
cpu: 13th Gen Intel(R) Core(TM) i5-1340P
BenchmarkCgoCall 6123471 195.8 ns/op
BenchmarkCgoCall-2 11794101 97.74 ns/op
BenchmarkCgoCall-4 22250806 51.30 ns/op
BenchmarkCgoCall-8 33147904 34.16 ns/op
BenchmarkCgoCall-16 53388628 22.41 ns/op
PASS
ok github.com/shanemhansen/cgobench 6.364s
$ go-11 test -cpu=1,2,4,8,16 -bench Gcc
goos: linux
goarch: amd64
pkg: github.com/shanemhansen/cgobench
cpu: 13th Gen Intel(R) Core(TM) i5-1340P
BenchmarkGccCall 414216266 3.037 ns/op
BenchmarkGccCall-2 788898944 1.523 ns/op
BenchmarkGccCall-4 1000000000 0.7670 ns/op
BenchmarkGccCall-8 1000000000 0.4909 ns/op
BenchmarkGccCall-16 1000000000 0.3488 ns/op
PASS
ok github.com/shanemhansen/cgobench 4.806s
$ go-11 test -cpu=1,2,4,8,16 -bench EmptyCall
goos: linux
goarch: amd64
pkg: github.com/shanemhansen/cgobench
cpu: 13th Gen Intel(R) Core(TM) i5-1340P
BenchmarkEmptyCallInlineable 1000000000 0.5483 ns/op
BenchmarkEmptyCallInlineable-2 1000000000 0.2752 ns/op
BenchmarkEmptyCallInlineable-4 1000000000 0.1463 ns/op
BenchmarkEmptyCallInlineable-8 1000000000 0.1295 ns/op
BenchmarkEmptyCallInlineable-16 1000000000 0.1225 ns/op
BenchmarkEmptyCall 499314484 2.401 ns/op
BenchmarkEmptyCall-2 977968472 1.202 ns/op
BenchmarkEmptyCall-4 1000000000 0.6316 ns/op
BenchmarkEmptyCall-8 1000000000 0.4111 ns/op
BenchmarkEmptyCall-16 1000000000 0.2765 ns/op
PASS
ok github.com/shanemhansen/cgobench 5.707s
Hence the GccGo version of calling the C function is in the same ballpark as for a native Go function call. This is as to be expected when using that mechanism.So using various C libraries does not necessarily have to involve the overhead from Cgo.
diff --git a/bench.go b/bench.go
index 8852c75..7bfd870 100644
--- a/bench.go
+++ b/bench.go
@@ -15,3 +15,10 @@ func Call() {
func CgoCall() {
C.trivial_add(1,2)
}
+
+//go:linkname c_trivial_add trivial_add
+func c_trivial_add(a int, b int) int
+
+func GccCall() {
+ c_trivial_add(1,2)
+}
diff --git a/bench_test.go b/bench_test.go
index 9523668..c390c63 100644
--- a/bench_test.go
+++ b/bench_test.go
@@ -43,3 +43,6 @@ func BenchmarkEmptyCall(b *testing.B) {
func BenchmarkCgoCall(b *testing.B) {
pbench(b, CgoCall)
}
+func BenchmarkGccCall(b *testing.B) {
+ pbench(b, GccCall)
+}
