Add benchmark and fast path for BufReader::read_exact

1 files changed, 12 insertions, 0 deletions

diff --git a/library/std/src/io/buffered/tests.rs b/library/std/src/io/buffered/tests.rs
index 66a64f667ba..f6c2b499567 100644
--- a/library/std/src/io/buffered/tests.rs
+++ b/library/std/src/io/buffered/tests.rs
@@ -444,6 +444,18 @@ fn bench_buffered_reader(b: &mut test::Bencher) {
 }
 
 #[bench]
+fn bench_buffered_reader_small_reads(b: &mut test::Bencher) {
+    let data = (0..u8::MAX).cycle().take(1024 * 4).collect::<Vec<_>>();
+    b.iter(|| {
+        let mut reader = BufReader::new(&data[..]);
+        let mut buf = [0u8; 4];
+        for _ in 0..1024 {
+            reader.read_exact(&mut buf).unwrap();
+        }
+    });
+}
+
+#[bench]
 fn bench_buffered_writer(b: &mut test::Bencher) {
     b.iter(|| BufWriter::new(io::sink()));
 }