--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/stress/gc/TestStressRSetCoarsening.java	Wed Feb 03 19:13:31 2016 +0300
@@ -0,0 +1,334 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+import java.util.concurrent.TimeoutException;
+import sun.hotspot.WhiteBox;
+
+/*
+ * @test TestStressRSetCoarsening.java
+ * @key stress
+ * @bug 8146984 8147087
+ * @requires vm.gc=="G1" | vm.gc=="null"
+ * @requires os.maxMemory > 3G
+ *
+ * @summary Stress G1 Remembered Set by creating a lot of cross region links
+ * @library /testlibrary /testlibrary/whitebox
+ * @build sun.hotspot.WhiteBox
+ * @run main ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm/timeout=300
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx500m -XX:G1HeapRegionSize=1m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening  1  0 300
+ * @run main/othervm/timeout=300
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx500m -XX:G1HeapRegionSize=8m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening  1 10 300
+ * @run main/othervm/timeout=300
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx500m -XX:G1HeapRegionSize=32m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening 42 10 300
+ * @run main/othervm/timeout=300
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx500m -XX:G1HeapRegionSize=1m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening  2 0 300
+ * @run main/othervm/timeout=1800
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx1G -XX:G1HeapRegionSize=1m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening 500 0  1800
+ * @run main/othervm/timeout=1800
+ *     -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UseG1GC
+ *     -XX:+IgnoreUnrecognizedVMOptions -XX:+PrintGC -XX:+PrintGCTimeStamps -Xlog:gc
+ *     -Xmx1G -XX:G1HeapRegionSize=1m -XX:MaxGCPauseMillis=1000 TestStressRSetCoarsening 10  10 1800
+ */
+
+/**
+ * What the test does.
+ * Preparation stage:
+ *   Fill out ~90% of the heap with objects, each object is an object array.
+ *   If we want to allocate K objects per region, we calculate N to meet:
+ *      sizeOf(Object[N]) ~= regionSize / K
+ * Stress stage:
+ *   No more allocation, so no more GC.
+ *   We will perform a number of  iterations. On each iteration i,
+ *   for each pair of regions Rx and Ry we will set c[i] references
+ *   from Rx to Ry. If c[i] less than c[i-1] at the end of iteration
+ *   concurrent mark cycle will be initiated (to recalculate remembered sets).
+ *   As the result RSet will be growing up and down, up and down many times.
+ *
+ * The test expects: no crash and no timeouts.
+ *
+ * Test Parameters:
+ *   args[0] - number of objects per Heap Region (1 - means humongous)
+ *   args[1] - number of regions to refresh to provoke GC at the end of cycle.
+ *             (0 - means no GC, i.e. no reading from RSet)
+ *   args[2] - timeout in seconds (to stop execution to avoid jtreg timeout)
+ */
+public class TestStressRSetCoarsening {
+
+    public static void main(String... args) throws InterruptedException {
+        if (args.length != 3) {
+            throw new IllegalArgumentException("Wrong number of arguments " + args.length);
+        }
+        int objectsPerRegion = Integer.parseInt(args[0]); // 1 means humongous
+        int regsToRefresh = Integer.parseInt(args[1]);  // 0 means no regions to refresh at the end of cycle
+        int timeout = Integer.parseInt(args[2]); // in seconds, test should stop working eariler
+        new TestStressRSetCoarsening(objectsPerRegion, regsToRefresh, timeout).go();
+    }
+
+    private static final long KB = 1024;
+    private static final long MB = 1024 * KB;
+
+    private static final WhiteBox WB = WhiteBox.getWhiteBox();
+
+    public final Object[][] storage;
+
+    /**
+     * Number of objects per region. This is a test parameter.
+     */
+    public final int K;
+
+    /**
+     * Length of object array: sizeOf(Object[N]) ~= regionSize / K
+     * N will be calculated as function of K.
+     */
+    public final int N;
+
+    /**
+     * How many regions involved into testing.
+     * Will be calculated as heapFractionToAllocate * freeRegionCount.
+     */
+    public final int regionCount;
+
+    /**
+     * How much heap to use.
+     */
+    public final float heapFractionToAllocate = 0.9f;
+
+    /**
+     * How many regions to be refreshed at the end of cycle.
+     * This is a test parameter.
+     */
+    public final int regsToRefresh;
+
+    /**
+     * Initial time.
+     */
+    public final long start;
+
+    /**
+     * Time when the test should stop working.
+     */
+    public final long finishAt;
+
+    /**
+     * Does pre-calculation and allocate necessary objects.
+     *
+     * @param objPerRegions how many objects per G1 heap region
+     */
+    TestStressRSetCoarsening(int objPerRegions, int regsToRefresh, int timeout) {
+        this.K = objPerRegions;
+        this.regsToRefresh = regsToRefresh;
+        this.start = System.currentTimeMillis();
+        this.finishAt = start + timeout * 900; // 10% ahead of jtreg timeout
+
+        long regionSize = WB.g1RegionSize();
+
+        // How many free regions
+        Runtime rt = Runtime.getRuntime();
+        long used = rt.totalMemory() - rt.freeMemory();
+        long totalFree = rt.maxMemory() - used;
+        regionCount = (int) ((totalFree / regionSize) * heapFractionToAllocate);
+        long toAllocate = regionCount * regionSize;
+        System.out.println("%% Test parameters");
+        System.out.println("%%   Objects per region              : " + K);
+        System.out.println("%%   Heap fraction to allocate       : " + (int) (heapFractionToAllocate * 100) + "%");
+        System.out.println("%%   Regions to refresh to provoke GC: " + regsToRefresh);
+
+        System.out.println("%% Memory");
+        System.out.println("%%   used          :        " + used / MB + "M");
+        System.out.println("%%   available     :        " + totalFree / MB + "M");
+        System.out.println("%%   to allocate   :        " + toAllocate / MB + "M");
+        System.out.println("%%     (in regs)   :        " + regionCount);
+        System.out.println("%%   G1 Region Size:        " + regionSize / MB + "M");
+
+        int refSize = WB.getHeapOopSize();
+
+        // Calculate N:    K*sizeOf(Object[N]) ~= regionSize
+        //                 sizeOf(Object[N]) ~=  (N+4)*refSize
+        // ==>
+        //                 N = regionSize / K / refSize - 4;
+        N = (int) ((regionSize / K) / refSize) - 5;
+
+        /*
+         *   --------------
+         *   region0   storage[0]        = new Object[N]
+         *             ...
+         *             storage[K-1]      = new Object[N]
+         *   ---------------
+         *   region1   storage[K]        = new Object[N]
+         *             ...
+         *             storage[2*K - 1]  = new Object[N]
+         *   --------------
+         *   ...
+         *   --------------
+         *   regionX   storage[X*K]         = new Object[N]
+         *             ...
+         *             storage[(X+1)*K -1]  = new Object[N]
+         *    where X = HeapFraction * TotalRegions
+         *   -------------
+         */
+        System.out.println("%% Objects");
+        System.out.println("%%   N (array length)      : " + N);
+        System.out.println("%%   K (objects in regions): " + K);
+        System.out.println("%%   Reference size        : " + refSize);
+        System.out.println("%%   Approximate obj size  : " + (N + 2) * refSize / KB + "K)");
+
+        storage = new Object[regionCount * K][];
+        for (int i = 0; i < storage.length; i++) {
+            storage[i] = new Object[N];
+        }
+    }
+
+    public void go() throws InterruptedException {
+        // threshold for sparce -> fine
+        final int FINE = WB.getIntxVMFlag("G1RSetSparseRegionEntries").intValue();
+
+        // threshold for fine -> coarse
+        final int COARSE = WB.getIntxVMFlag("G1RSetRegionEntries").intValue();
+
+        // regToRegRefCounts - array of reference counts from region to region
+        // at the the end of iteration.
+        // The number of test iterations is array length - 1.
+        // If c[i] > c[i-1] then during the iteration i more references will
+        // be created.
+        // If c[i] < c[i-1] then some referenes will be cleaned.
+        int[] regToRegRefCounts = {0, FINE / 2, 0, FINE, (FINE + COARSE) / 2, 0,
+            COARSE, COARSE + 10, FINE + 1, FINE / 2, 0};
+
+        // For progress tracking
+        int[] progress = new int[regToRegRefCounts.length];
+        progress[0] = 0;
+        for (int i = 1; i < regToRegRefCounts.length; i++) {
+            progress[i] = progress[i - 1] + Math.abs(regToRegRefCounts[i] - regToRegRefCounts[i - 1]);
+        }
+        try {
+            for (int i = 1; i < regToRegRefCounts.length; i++) {
+                int pre = regToRegRefCounts[i - 1];
+                int cur = regToRegRefCounts[i];
+                float prog = ((float) progress[i - 1] / progress[progress.length - 1]);
+
+                System.out.println("%% step " + i
+                        + " out of " + (regToRegRefCounts.length - 1)
+                        + " (~" + (int) (100 * prog) + "% done)");
+                System.out.println("%%      " + pre + "  --> " + cur);
+                for (int to = 0; to < regionCount; to++) {
+                    // Select a celebrity object that we will install references to.
+                    // The celebrity will be referred from all other regions.
+                    // If the number of references after should be less than they
+                    // were before, select NULL.
+                    Object celebrity = cur > pre ? storage[to * K] : null;
+                    for (int from = 0; from < regionCount; from++) {
+                        if (to == from) {
+                            continue; // no need to refer to itself
+                        }
+
+                        int step = cur > pre ? +1 : -1;
+                        for (int rn = pre; rn != cur; rn += step) {
+                            storage[getY(to, from, rn)][getX(to, from, rn)] = celebrity;
+                            if (System.currentTimeMillis() > finishAt) {
+                                throw new TimeoutException();
+                            }
+                        }
+                    }
+                }
+                if (pre > cur) {
+                    // Number of references went down.
+                    // Need to provoke recalculation of RSet.
+                    WB.g1StartConcMarkCycle();
+                    while (WB.g1InConcurrentMark()) {
+                        Thread.sleep(1);
+                    }
+                }
+
+                // To force the use of rememebered set entries we need to provoke a GC.
+                // To induce some fragmentation, and some mixed GCs, we need
+                // to make a few objects unreachable.
+                for (int toClean = i * regsToRefresh; toClean < (i + 1) * regsToRefresh; toClean++) {
+                    int to = toClean % regionCount;
+                    // Need to remove all references from all regions to the region 'to'
+                    for (int from = 0; from < regionCount; from++) {
+                        if (to == from) {
+                            continue; // no need to refer to itself
+                        }
+                        for (int rn = 0; rn <= cur; rn++) {
+                            storage[getY(to, from, rn)][getX(to, from, rn)] = null;
+                        }
+                    }
+                    // 'Refresh' storage elements for the region 'to'
+                    // After that loop all 'old' objects in the region 'to'
+                    // should become unreachable.
+                    for (int k = 0; k < K; k++) {
+                        storage[(to * K + k) % storage.length] = new Object[N];
+                    }
+                }
+            }
+        } catch (TimeoutException e) {
+            System.out.println("%% TIMEOUT!!!");
+        }
+        long now = System.currentTimeMillis();
+        System.out.println("%% Summary");
+        System.out.println("%%   Time spent          : " + ((now - start) / 1000) + " seconds");
+        System.out.println("%%   Free memory left    : " + Runtime.getRuntime().freeMemory() / KB + "K");
+        System.out.println("%% Test passed");
+    }
+
+    /**
+     * Returns X index in the Storage of the reference #rn from the region
+     * 'from' to the region 'to'.
+     *
+     * @param to region # to refer to
+     * @param from region # to refer from
+     * @param rn number of reference
+     *
+     * @return X index in the range: [0 ... N-1]
+     */
+    private int getX(int to, int from, int rn) {
+        return (rn * regionCount + to) % N;
+    }
+
+    /**
+     * Returns Y index in the Storage of the reference #rn from the region
+     * 'from' to the region 'to'.
+     *
+     * @param to region # to refer to
+     * @param from region # to refer from
+     * @param rn number of reference
+     *
+     * @return Y index in the range: [0 ... K*regionCount -1]
+     */
+    private int getY(int to, int from, int rn) {
+        return ((rn * regionCount + to) / N + from * K) % (regionCount * K);
+    }
+}
+