--- /dev/null	2018-12-17 06:09:15.256999270 +0100
+++ new/test/micro/org/openjdk/bench/java/util/HashMapBench.java	2018-12-17 07:25:17.808963313 +0100
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package org.openjdk.bench.java.util;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+import static java.util.stream.Collectors.toMap;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@State(Scope.Thread)
+public class HashMapBench {
+    private Map<Integer, Integer> bigMapToAdd;
+    private Random r;
+
+    @Setup
+    public void setup() {
+        this.r = new Random();
+        this.bigMapToAdd = IntStream.range(0, 1_000_000).boxed().collect(toMap(i -> 7 + i * 128, i -> r.nextInt()));
+    }
+
+    @Benchmark
+    public int putAllWithBigMapToNonEmptyMap() {
+        var map = new HashMap<Integer, Integer>();
+        map.put(-1, -1);
+        map.putAll(bigMapToAdd);
+        return map.size();
+    }
+
+    @Benchmark
+    public int putAllWithBigMapToEmptyMap() {
+        var map = new HashMap<Integer, Integer>();
+        map.putAll(bigMapToAdd);
+        return map.size();
+    }
+
+    @Benchmark
+    public int put() {
+        var map = new HashMap<Integer, Integer>();
+        for (int k : bigMapToAdd.keySet()) {
+            map.put(k, bigMapToAdd.get(k));
+        }
+        return map.size();
+    }
+}