add benchmarks

benches/mod.rs

@@ -0,0 +1,24 @@
+#![feature(test)]
+extern crate test;
+extern crate getrandom;
+
+#[bench]
+fn bench_64(b: &mut test::Bencher) {
+    let mut buf = [0u8; 64];
+    b.iter(|| {
+        getrandom::getrandom(&mut buf[..]).unwrap();
+        test::black_box(&buf);        
+    });
+    b.bytes = buf.len() as u64;
+}
+
+#[bench]
+fn bench_65536(b: &mut test::Bencher) {
+    let mut buf = [0u8; 65536];
+    b.iter(|| {
+        getrandom::getrandom(&mut buf[..]).unwrap();
+        test::black_box(&buf);        
+    });
+    b.bytes = buf.len() as u64;
+}
+