--- /dev/null	2020-02-11 09:31:42.601809740 +0100
+++ new/test/jdk/jdk/internal/platform/cgroup/TestCgroupSubsystemController.java	2020-02-11 18:28:08.386513732 +0100
@@ -0,0 +1,217 @@
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import jdk.internal.platform.CgroupSubsystemController;
+import jdk.test.lib.Utils;
+import jdk.test.lib.util.FileUtils;
+
+/*
+ * Copyright (c) 2020, Red Hat Inc.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * 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.
+ */
+
+/*
+ * @test
+ * @requires os.family == "linux"
+ * @modules java.base/jdk.internal.platform
+ * @library /test/lib
+ * @run junit/othervm TestCgroupSubsystemController
+ */
+
+/**
+ *
+ * Basic unit test for CgroupSubsystemController
+ *
+ */
+public class TestCgroupSubsystemController {
+
+    private static final double DELTA = 0.01;
+    private Path existingDirectory;
+    private Path existingFile;
+    private String existingFileName = "test-controller-file";
+    private String existingFileContents = "foobar";
+    private String doubleValueContents = "1.5";
+    private String longValueContents = "3000000000";
+    private String longValueMatchingLineContents = "testme\n" +
+                                                   "itemfoo 25";
+    private String longEntryContents = "s 1\n" +
+                                       "t 2";
+    private String longEntryName = "longEntry";
+    private String longEntryMatchingLineName = "longMatchingLine";
+    private String doubleValueName = "doubleValue";
+    private String longValueName = "longValue";
+    private CgroupSubsystemController mockController;
+
+    @Before
+    public void setup() {
+        try {
+            existingDirectory = Utils.createTempDirectory(TestCgroupSubsystemController.class.getSimpleName());
+            existingFile = Paths.get(existingDirectory.toString(), existingFileName);
+            Files.writeString(existingFile, existingFileContents, StandardCharsets.UTF_8);
+            Path longFile = Paths.get(existingDirectory.toString(), longValueName);
+            Files.writeString(longFile, longValueContents);
+            Path doubleFile = Paths.get(existingDirectory.toString(), doubleValueName);
+            Files.writeString(doubleFile, doubleValueContents);
+            Path longEntryFile = Paths.get(existingDirectory.toString(), longEntryName);
+            Files.writeString(longEntryFile, longEntryContents);
+            Path longMatchingLine = Paths.get(existingDirectory.toString(), longEntryMatchingLineName);
+            Files.writeString(longMatchingLine, longValueMatchingLineContents);
+            mockController = new MockCgroupSubsystemController(existingDirectory.toString());
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @After
+    public void teardown() {
+        try {
+            FileUtils.deleteFileTreeWithRetry(existingDirectory);
+        } catch (IOException e) {
+            System.err.println("Teardown failed. " + e.getMessage());
+        }
+    }
+
+    @Test
+    public void getStringValueNullController() {
+        String val = CgroupSubsystemController.getStringValue(null, "ignore");
+        assertNull(val);
+    }
+
+    @Test
+    public void getStringValueIOException() throws IOException {
+        String val = CgroupSubsystemController.getStringValue(mockController, "don-t-exist.txt");
+        assertNull(val);
+    }
+
+    @Test
+    public void getStringValueSuccess() {
+        String actual = CgroupSubsystemController.getStringValue(mockController, existingFileName);
+        assertEquals(existingFileContents, actual);
+    }
+
+    @Test
+    public void convertStringToLong() {
+        String strVal = "1230";
+        long longVal = Long.parseLong(strVal);
+        long actual = CgroupSubsystemController.convertStringToLong(strVal, -1L, 0);
+        assertEquals(longVal, actual);
+
+        String overflowVal = "9223372036854775808"; // Long.MAX_VALUE + 1
+        long overflowDefault = -1;
+        actual = CgroupSubsystemController.convertStringToLong(overflowVal, overflowDefault, 0);
+        assertEquals(overflowDefault, actual);
+        overflowDefault = Long.MAX_VALUE;
+        actual = CgroupSubsystemController.convertStringToLong(overflowVal, overflowDefault, 0);
+        assertEquals(overflowDefault, actual);
+    }
+
+    @Test
+    public void convertStringRangeToIntArray() {
+        assertNull(CgroupSubsystemController.stringRangeToIntArray(null));
+        assertNull(CgroupSubsystemController.stringRangeToIntArray(""));
+        String strRange = "2,4,6";
+        int[] actual = CgroupSubsystemController.stringRangeToIntArray(strRange);
+        int[] expected = new int[] { 2, 4, 6 };
+        assertTrue(Arrays.equals(expected, actual));
+        strRange = "6,1-3";
+        actual = CgroupSubsystemController.stringRangeToIntArray(strRange);
+        expected = new int[] { 1, 2, 3, 6 };
+        assertTrue(Arrays.equals(expected, actual));
+    }
+
+    @Test
+    public void getDoubleValue() {
+        double defaultValue = -3;
+        double actual = CgroupSubsystemController.getDoubleValue(null, null, defaultValue);
+        assertEquals(defaultValue, actual, DELTA);
+        double expected = Double.parseDouble(doubleValueContents);
+        actual = CgroupSubsystemController.getDoubleValue(mockController, doubleValueName, defaultValue);
+        assertEquals(expected, actual, DELTA);
+        actual = CgroupSubsystemController.getDoubleValue(mockController, "don't-exist", defaultValue);
+        assertEquals(defaultValue, actual, DELTA);
+    }
+
+    @Test
+    public void getLongValue() {
+        long defaultValue = -4;
+        long actual = CgroupSubsystemController.getLongValue(null, null, Long::parseLong, defaultValue);
+        assertEquals(defaultValue, actual);
+        actual = CgroupSubsystemController.getLongValue(mockController, "dont-exist", Long::parseLong, defaultValue);
+        assertEquals(defaultValue, actual);
+        long expected = Long.parseLong(longValueContents);
+        actual = CgroupSubsystemController.getLongValue(mockController, longValueName, Long::parseLong, defaultValue);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void getLongEntry() {
+        long defaultValue = -5;
+        long actual = CgroupSubsystemController.getLongEntry(null, null, "no-matter", defaultValue);
+        assertEquals(defaultValue, actual);
+        actual = CgroupSubsystemController.getLongEntry(mockController, "dont-exist", "foo-bar", defaultValue);
+        assertEquals(defaultValue, actual);
+        actual = CgroupSubsystemController.getLongEntry(mockController, longEntryName, "t", defaultValue);
+        assertEquals(2, actual);
+    }
+
+    @Test
+    public void getLongMatchingLine() {
+        long defaultValue = -6;
+        long actual = CgroupSubsystemController.getLongValueMatchingLine(null, null, "no-matter", Long::parseLong, defaultValue);
+        assertEquals(defaultValue, actual);
+        actual = CgroupSubsystemController.getLongValueMatchingLine(mockController, "dont-exist", "no-matter", Long::parseLong, defaultValue);
+        assertEquals(defaultValue, actual);
+        actual = CgroupSubsystemController.getLongValueMatchingLine(mockController, longEntryMatchingLineName, "item", TestCgroupSubsystemController::convertLong, defaultValue);
+        assertEquals(25, actual);
+    }
+
+    public static long convertLong(String line) {
+        return Long.parseLong(line.split("\\s+")[1]);
+    }
+
+    static class MockCgroupSubsystemController implements CgroupSubsystemController {
+
+        private final String path;
+
+        public MockCgroupSubsystemController(String path) {
+            this.path = path;
+        }
+
+        @Override
+        public String path() {
+            return path;
+        }
+
+    }
+
+}