view test/compiler/6968348/Test6968348.java @ 2149:7e37af9d69ef

7011379: G1: overly long concurrent marking cycles Summary: This changeset introduces filtering of SATB buffers at the point when they are about to be enqueued. If this filtering clears enough entries on each buffer, the buffer can then be re-used and not enqueued. This cuts down the number of SATB buffers that need to be processed by the concurrent marking threads. Reviewed-by: johnc, ysr
author tonyp
date Wed, 19 Jan 2011 09:35:17 -0500
parents 52e82a6bedaf
children
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/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 * 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
 * @bug 6968348
 * @summary Byteswapped memory access can point to wrong location after JIT
 *
 * @run main Test6968348
 */

import sun.misc.Unsafe;
import java.lang.reflect.*;

public class Test6968348 {
    static Unsafe unsafe;
    static final long[] buffer = new long[4096];
    static int array_long_base_offset;

    public static void main(String[] args) throws Exception {
        Class c = Test6968348.class.getClassLoader().loadClass("sun.misc.Unsafe");
        Field f = c.getDeclaredField("theUnsafe");
        f.setAccessible(true);
        unsafe = (Unsafe)f.get(c);
        array_long_base_offset = unsafe.arrayBaseOffset(long[].class);

        for (int n = 0; n < 100000; n++) {
            test();
        }
    }

    public static void test() {
        for (long i = array_long_base_offset; i < 4096; i += 8) {
            unsafe.putLong(buffer, i, Long.reverseBytes(i));
        }
    }
}