add the bench test and the license info

util/memory/bench_test.go

@@ -0,0 +1,30 @@
+// Copyright 2018 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package memory
+
+import (
+	"testing"
+)
+
+func BenchmarkMemTotal(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = MemTotal()
+	}
+}
+
+func BenchmarkMemUsed(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_, _ = MemUsed()
+	}
+}

util/memory/meminfo.go

@@ -1,3 +1,16 @@
+// Copyright 2018 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package memory
 
 import (