1 /*
   2  * Copyright (c) 2014, 2015, 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 /**
  25  * @test TestSmallHeap
  26  * @bug 8067438
  27  * @requires vm.gc=="null"
  28  * @requires (vm.opt.AggressiveOpts=="null") | (vm.opt.AggressiveOpts=="false")
  29  * @requires vm.compMode != "Xcomp"
  30  * @requires vm.opt.UseCompressedOops != false
  31  * @summary Verify that starting the VM with a small heap works
  32  * @library /testlibrary /test/lib
  33  * @modules java.base/jdk.internal.misc
  34  * @modules java.management/sun.management
  35  * @ignore 8076621
  36  * @build TestSmallHeap
  37  * @run main ClassFileInstaller sun.hotspot.WhiteBox
  38  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx2m -XX:+UseParallelGC TestSmallHeap
  39  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx2m -XX:+UseSerialGC TestSmallHeap
  40  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx2m -XX:+UseG1GC TestSmallHeap
  41  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx2m -XX:+UseConcMarkSweepGC TestSmallHeap
  42  */
  43 
  44 /* Note: It would be nice to verify the minimal supported heap size (2m) here,
  45  * but we align the heap size based on the card table size. And the card table
  46  * size is aligned based on the minimal pages size provided by the os. This
  47  * means that on most platforms, where the minimal page size is 4k, we get a
  48  * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and
  49  * get a minimal heap size of 4m. And on platforms where the page size is 64k
  50  * we get a minimal heap size of 32m. We never use large pages for the card table.
  51  *
  52  * There is also no check in the VM for verifying that the maximum heap size
  53  * is larger than the supported minimal heap size. This means that specifying
  54  * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m or 32m).
  55  *
  56  * To work around these rather strange behaviors this test uses -Xmx2m but then
  57  * calculates what the expected heap size should be. The calculation is a
  58  * simplified version of the code in the VM. We assume that the card table will
  59  * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
  60  * So, the expected heap size is page_size * 512.
  61  */
  62 
  63 import jdk.test.lib.*;
  64 import com.sun.management.HotSpotDiagnosticMXBean;
  65 import java.lang.management.ManagementFactory;
  66 import static jdk.test.lib.Asserts.*;
  67 
  68 import sun.hotspot.WhiteBox;
  69 
  70 public class TestSmallHeap {
  71 
  72     public static void main(String[] args) {
  73         WhiteBox wb = WhiteBox.getWhiteBox();
  74         int pageSize = wb.getVMPageSize();
  75         int heapBytesPerCard = 512;
  76         long expectedMaxHeap = pageSize * heapBytesPerCard;
  77         String maxHeap
  78             = ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
  79                 .getVMOption("MaxHeapSize").getValue();
  80         assertEQ(Long.parseLong(maxHeap), expectedMaxHeap);
  81     }
  82 }