1 /*
   2  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 package gc.z;
  25 
  26 /*
  27  * @test TestPageCacheFlush
  28  * @requires vm.gc.Z & !vm.graal.enabled
  29  * @summary Test ZGC page cache flushing
  30  * @library / /test/lib
  31  * @run main/othervm gc.z.TestPageCacheFlush
  32  */
  33 
  34 import java.util.LinkedList;
  35 import jdk.test.lib.process.ProcessTools;
  36 
  37 import static gc.testlibrary.Allocation.blackHole;
  38 
  39 public class TestPageCacheFlush {
  40     static class Test {
  41         private static final int K = 1024;
  42         private static final int M = K * K;
  43         private static volatile LinkedList<byte[]> keepAlive;
  44 
  45         public static void fillPageCache(int size) {
  46             System.out.println("Begin allocate (" + size + ")");
  47 
  48             keepAlive = new LinkedList<>();
  49 
  50             try {
  51                 for (;;) {
  52                     keepAlive.add(new byte[size]);
  53                 }
  54             } catch (OutOfMemoryError e) {
  55                 keepAlive = null;
  56                 System.gc();
  57             }
  58 
  59             System.out.println("End allocate (" + size + ")");
  60         }
  61 
  62         public static void main(String[] args) throws Exception {
  63             // Allocate small objects to fill the page cache with small pages
  64             fillPageCache(10 * K);
  65 
  66             // Allocate large objects to provoke page cache flushing to rebuild
  67             // cached small pages into large pages
  68             fillPageCache(10 * M);
  69         }
  70     }
  71 
  72     public static void main(String[] args) throws Exception {
  73         ProcessTools.executeProcess(ProcessTools.createJavaProcessBuilder(
  74                                     "-XX:+UseZGC",
  75                                     "-Xms128M",
  76                                     "-Xmx128M",
  77                                     "-Xlog:gc,gc+init,gc+heap=debug",
  78                                     Test.class.getName()))
  79                     .outputTo(System.out)
  80                     .errorTo(System.out)
  81                     .shouldContain("Page Cache Flushed:")
  82                     .shouldHaveExitValue(0);
  83     }
  84 }