Implementation of GC phase pause events

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/GCImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2022, 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
@@ -207,6 +207,8 @@ private boolean collectImpl(GCCause cause, long requestingNanoTime, boolean forc
         precondition();
 
         NoAllocationVerifier nav = noAllocationVerifier.open();
+
+        long startTicks = JfrGCEventSupport.startGCPhasePause();
         try {
             outOfMemory = doCollectImpl(cause, requestingNanoTime, forceFullGC, false);
             if (outOfMemory) {
@@ -219,6 +221,7 @@ private boolean collectImpl(GCCause cause, long requestingNanoTime, boolean forc
                 }
             }
         } finally {
+            JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), cause.getName(), startTicks);
             nav.close();
         }
 
@@ -231,14 +234,19 @@ private boolean doCollectImpl(GCCause cause, long requestingNanoTime, boolean fo
 
         boolean incremental = !forceNoIncremental && !policy.shouldCollectCompletely(false);
         boolean outOfMemory = false;
+
         if (incremental) {
+            long startTicks = JfrGCEventSupport.startGCPhasePause();
             outOfMemory = doCollectOnce(cause, requestingNanoTime, false, false);
+            JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Incremental GC", startTicks);
         }
         if (!incremental || outOfMemory || forceFullGC || policy.shouldCollectCompletely(incremental)) {
             if (incremental) { // uncommit unaligned chunks
                 CommittedMemoryProvider.get().afterGarbageCollection();
             }
+            long startTicks = JfrGCEventSupport.startGCPhasePause();
             outOfMemory = doCollectOnce(cause, requestingNanoTime, true, incremental);
+            JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Full GC", startTicks);
         }
 
         HeapImpl.getChunkProvider().freeExcessAlignedChunks();
@@ -495,15 +503,18 @@ public boolean isCompleteCollection() {
     /** Scavenge, either from dirty roots or from all roots, and process discovered references. */
     private void scavenge(boolean incremental) {
         GreyToBlackObjRefVisitor.Counters counters = greyToBlackObjRefVisitor.openCounters();
+        long startTicks;
         try {
             Timer rootScanTimer = timers.rootScan.open();
+            startTicks = JfrGCEventSupport.startGCPhasePause();
             try {
                 if (incremental) {
                     cheneyScanFromDirtyRoots();
                 } else {
                     cheneyScanFromRoots();
                 }
             } finally {
+                JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), incremental ? "Incremental Scan Roots" : "Scan Roots", startTicks);
                 rootScanTimer.close();
             }
 
@@ -515,23 +526,28 @@ private void scavenge(boolean incremental) {
                      * operation. To avoid side-effects between the code cache cleaning and the GC
                      * core, it is crucial that all the GC core work finished before.
                      */
+                    startTicks = JfrGCEventSupport.startGCPhasePause();
                     cleanRuntimeCodeCache();
                 } finally {
+                    JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Clean Runtime CodeCache", startTicks);
                     cleanCodeCacheTimer.close();
                 }
             }
 
             Timer referenceObjectsTimer = timers.referenceObjects.open();
             try {
+                startTicks = JfrGCEventSupport.startGCPhasePause();
                 Reference<?> newlyPendingList = ReferenceObjectProcessing.processRememberedReferences();
                 HeapImpl.getHeapImpl().addToReferencePendingList(newlyPendingList);
             } finally {
+                JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Process Remembered References", startTicks);
                 referenceObjectsTimer.close();
             }
 
             Timer releaseSpacesTimer = timers.releaseSpaces.open();
             try {
                 assert chunkReleaser.isEmpty();
+                startTicks = JfrGCEventSupport.startGCPhasePause();
                 releaseSpaces();
 
                 /*
@@ -542,10 +558,13 @@ private void scavenge(boolean incremental) {
                 boolean keepAllAlignedChunks = incremental;
                 chunkReleaser.release(keepAllAlignedChunks);
             } finally {
+                JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Release Spaces", startTicks);
                 releaseSpacesTimer.close();
             }
 
+            startTicks = JfrGCEventSupport.startGCPhasePause();
             swapSpaces();
+            JfrGCEventSupport.emitGCPhasePauseEvent(getCollectionEpoch(), "Swap Spaces", startTicks);
         } finally {
             counters.close();
         }

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/JfrGCEventSupport.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2022, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2022, Red Hat Inc. 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+package com.oracle.svm.core.genscavenge;
+
+import org.graalvm.nativeimage.Platform;
+import org.graalvm.nativeimage.Platforms;
+import org.graalvm.nativeimage.StackValue;
+import org.graalvm.word.UnsignedWord;
+
+import com.oracle.svm.core.annotate.Uninterruptible;
+import com.oracle.svm.core.jfr.JfrBuffer;
+import com.oracle.svm.core.jfr.JfrEnabled;
+import com.oracle.svm.core.jfr.JfrEvents;
+import com.oracle.svm.core.jfr.JfrNativeEventWriter;
+import com.oracle.svm.core.jfr.JfrNativeEventWriterData;
+import com.oracle.svm.core.jfr.JfrNativeEventWriterDataAccess;
+import com.oracle.svm.core.jfr.JfrThreadLocal;
+import com.oracle.svm.core.jfr.JfrTicks;
+import com.oracle.svm.core.jfr.SubstrateJVM;
+import com.oracle.svm.core.util.VMError;
+
+class JfrGCEventSupport {
+    public static final int MAX_PHASE_LEVEL = 4;
+    private static int currentPhase;
+
+    @Platforms(Platform.HOSTED_ONLY.class)
+    JfrGCEventSupport() {
+    }
+
+    public static long startGCPhasePause() {
+        if (!JfrEnabled.get()) {
+            return 0;
+        }
+        pushPausePhaseLevel();
+        return JfrTicks.elapsedTicks();
+    }
+
+    @Uninterruptible(reason = "Accesses a JFR buffer.")
+    public static void emitGCPhasePauseEvent(UnsignedWord gcEpoch, String name, long startTicks) {
+        if (!JfrEnabled.get()) {
+            return;
+        }
+
+        int level = popPausePhaseLevel();
+        JfrEvents event = getGCPhasePauseEvent(level);
+        if (SubstrateJVM.isRecording() && SubstrateJVM.get().isEnabled(event)) {
+            long end = JfrTicks.elapsedTicks();
+            JfrBuffer buffer = ((JfrThreadLocal) SubstrateJVM.getThreadLocal()).getNativeBuffer();
+            JfrNativeEventWriterData data = StackValue.get(JfrNativeEventWriterData.class);
+            JfrNativeEventWriterDataAccess.initialize(data, buffer);
+
+            JfrNativeEventWriter.beginEventWrite(data, false);
+            JfrNativeEventWriter.putLong(data, event.getId());
+            JfrNativeEventWriter.putLong(data, startTicks);
+            JfrNativeEventWriter.putLong(data, end - startTicks);
+            JfrNativeEventWriter.putEventThread(data);
+            JfrNativeEventWriter.putLong(data, gcEpoch.rawValue());
+            JfrNativeEventWriter.putString(data, name);
+            JfrNativeEventWriter.endEventWrite(data, false);
+        }
+    }
+
+    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
+    private static JfrEvents getGCPhasePauseEvent(int level) {
+        switch (level) {
+            case 0:
+                return JfrEvents.GCPhasePauseEvent;
+            case 1:
+                return JfrEvents.GCPhasePauseLevel1Event;
+            case 2:
+                return JfrEvents.GCPhasePauseLevel2Event;
+            case 3:
+                return JfrEvents.GCPhasePauseLevel3Event;
+            case 4:
+                return JfrEvents.GCPhasePauseLevel4Event;
+            default:
+                throw VMError.shouldNotReachHere("At most " + MAX_PHASE_LEVEL + " levels");
+        }
+    }
+
+    private static void pushPausePhaseLevel() {
+        assert currentPhase < MAX_PHASE_LEVEL;
+        currentPhase++;
+    }
+
+    @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)
+    private static int popPausePhaseLevel() {
+        assert currentPhase > 0;
+        currentPhase--;
+        return currentPhase;
+    }
+}

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/JfrEvents.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2022, 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
@@ -51,7 +51,12 @@ public enum JfrEvents {
     OSInformation("jdk.OSInformation"),
     PhysicalMemory("jdk.PhysicalMemory"),
     ExecutionSample("jdk.ExecutionSample"),
-    NativeMethodSample("jdk.NativeMethodSample");
+    NativeMethodSample("jdk.NativeMethodSample"),
+    GCPhasePauseEvent("jdk.GCPhasePause"),
+    GCPhasePauseLevel1Event("jdk.GCPhasePauseLevel1"),
+    GCPhasePauseLevel2Event("jdk.GCPhasePauseLevel2"),
+    GCPhasePauseLevel3Event("jdk.GCPhasePauseLevel3"),
+    GCPhasePauseLevel4Event("jdk.GCPhasePauseLevel4");
 
     private final long id;