--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/G1HeapRegionType.java	Fri Feb 12 09:19:10 2016 +0100
@@ -0,0 +1,47 @@
+/*
+ * 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.
+ *
+ */
+
+package sun.jvm.hotspot.gc.shared;
+
+//These definitions should be kept in sync with the definitions in the HotSpot code.
+
+public enum G1HeapRegionType {
+  Free ("Free"),
+  Eden ("Eden"),
+  Survivor ("Survivor"),
+  StartsHumongous ("Starts Humongous"),
+  ContinuesHumongous ("Continues Humongous"),
+  Old ("Old"),
+  Archive ("Archive"),
+  G1HeapRegionTypeEndSentinel ("G1HeapRegionTypeEndSentinel");
+
+  private final String value;
+
+  G1HeapRegionType(String val) {
+    this.value = val;
+  }
+  public String value() {
+    return value;
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1HeapRegionTraceType.hpp	Fri Feb 12 09:19:10 2016 +0100
@@ -0,0 +1,58 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_G1HEAPREGIONTRACETYPE_HPP
+#define SHARE_VM_GC_G1_G1HEAPREGIONTRACETYPE_HPP
+
+#include "memory/allocation.hpp"
+#include "utilities/debug.hpp"
+
+class G1HeapRegionTraceType : AllStatic {
+ public:
+  enum Type {
+    Free,
+    Eden,
+    Survivor,
+    StartsHumongous,
+    ContinuesHumongous,
+    Old,
+    Archive,
+    G1HeapRegionTypeEndSentinel
+  };
+
+  static const char* to_string(G1HeapRegionTraceType::Type type) {
+    switch (type) {
+      case Free:               return "Free";
+      case Eden:               return "Eden";
+      case Survivor:           return "Survivor";
+      case StartsHumongous:    return "Starts Humongous";
+      case ContinuesHumongous: return "Continues Humongous";
+      case Old:                return "Old";
+      case Archive:            return "Archive";
+      default: ShouldNotReachHere(); return NULL;
+    }
+  }
+};
+
+#endif // SHARE_VM_GC_G1_G1HEAPREGIONTRACETYPE_HPP

--- a/hotspot/src/share/vm/gc/g1/heapRegion.cpp	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/heapRegion.cpp	Fri Feb 12 09:19:10 2016 +0100
@@ -26,11 +26,13 @@
 #include "code/nmethod.hpp"
 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1HeapRegionTraceType.hpp"
 #include "gc/g1/g1OopClosures.inline.hpp"
 #include "gc/g1/heapRegion.inline.hpp"
 #include "gc/g1/heapRegionBounds.inline.hpp"
 #include "gc/g1/heapRegionManager.inline.hpp"
 #include "gc/g1/heapRegionRemSet.hpp"
+#include "gc/g1/heapRegionTracer.hpp"
 #include "gc/shared/genOopClosures.inline.hpp"
 #include "gc/shared/liveRange.hpp"
 #include "gc/shared/space.inline.hpp"
@@ -212,10 +214,41 @@
   _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 }
 
+void HeapRegion::set_free() {
+  report_region_type_change(G1HeapRegionTraceType::Free);
+  _type.set_free();
+}
+
+void HeapRegion::set_eden() {
+  report_region_type_change(G1HeapRegionTraceType::Eden);
+  _type.set_eden();
+}
+
+void HeapRegion::set_eden_pre_gc() {
+  report_region_type_change(G1HeapRegionTraceType::Eden);
+  _type.set_eden_pre_gc();
+}
+
+void HeapRegion::set_survivor() {
+  report_region_type_change(G1HeapRegionTraceType::Survivor);
+  _type.set_survivor();
+}
+
+void HeapRegion::set_old() {
+  report_region_type_change(G1HeapRegionTraceType::Old);
+  _type.set_old();
+}
+
+void HeapRegion::set_archive() {
+  report_region_type_change(G1HeapRegionTraceType::Archive);
+  _type.set_archive();
+}
+
 void HeapRegion::set_starts_humongous(HeapWord* obj_top, size_t fill_size) {
   assert(!is_humongous(), "sanity / pre-condition");
   assert(top() == bottom(), "should be empty");
 
+  report_region_type_change(G1HeapRegionTraceType::StartsHumongous);
   _type.set_starts_humongous();
   _humongous_start_region = this;
 
@@ -227,6 +260,7 @@
   assert(top() == bottom(), "should be empty");
   assert(first_hr->is_starts_humongous(), "pre-condition");
 
+  report_region_type_change(G1HeapRegionTraceType::ContinuesHumongous);
   _type.set_continues_humongous();
   _humongous_start_region = first_hr;
 }
@@ -272,6 +306,15 @@
   record_timestamp();
 }
 
+void HeapRegion::report_region_type_change(G1HeapRegionTraceType::Type to) {
+  HeapRegionTracer::send_region_type_change(_hrm_index,
+                                            get_trace_type(),
+                                            to,
+                                            (uintptr_t)bottom(),
+                                            used(),
+                                            (uint)allocation_context());
+}
+
 CompactibleSpace* HeapRegion::next_compaction_space() const {
   return G1CollectedHeap::heap()->next_compaction_region(this);
 }

--- a/hotspot/src/share/vm/gc/g1/heapRegion.hpp	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/heapRegion.hpp	Fri Feb 12 09:19:10 2016 +0100
@@ -27,6 +27,8 @@
 
 #include "gc/g1/g1AllocationContext.hpp"
 #include "gc/g1/g1BlockOffsetTable.hpp"
+#include "gc/g1/g1HeapRegionTraceType.hpp"
+#include "gc/g1/heapRegionTracer.hpp"
 #include "gc/g1/heapRegionType.hpp"
 #include "gc/g1/survRateGroup.hpp"
 #include "gc/shared/ageTable.hpp"
@@ -243,6 +245,8 @@
     return HeapRegion::block_size(addr); // Avoid virtual call
   }
 
+  void report_region_type_change(G1HeapRegionTraceType::Type to);
+
  protected:
   // The index of this region in the heap region sequence.
   uint  _hrm_index;
@@ -427,6 +431,7 @@
 
   const char* get_type_str() const { return _type.get_str(); }
   const char* get_short_type_str() const { return _type.get_short_str(); }
+  G1HeapRegionTraceType::Type get_trace_type() { return _type.get_trace_type(); }
 
   bool is_free() const { return _type.is_free(); }
 
@@ -637,15 +642,15 @@
     }
   }
 
-  void set_free() { _type.set_free(); }
+  void set_free();
 
-  void set_eden()        { _type.set_eden();        }
-  void set_eden_pre_gc() { _type.set_eden_pre_gc(); }
-  void set_survivor()    { _type.set_survivor();    }
+  void set_eden();
+  void set_eden_pre_gc();
+  void set_survivor();
 
-  void set_old() { _type.set_old(); }
+  void set_old();
 
-  void set_archive() { _type.set_archive(); }
+  void set_archive();
 
   // Determine if an object has been allocated since the last
   // mark performed by the collector. This returns true iff the object

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/heapRegionTracer.cpp	Fri Feb 12 09:19:10 2016 +0100
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2013, 2015, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/heapRegionTracer.hpp"
+#include "trace/tracing.hpp"
+
+void HeapRegionTracer::send_region_type_change(uint index,
+                                               G1HeapRegionTraceType::Type from,
+                                               G1HeapRegionTraceType::Type to,
+                                               uintptr_t start,
+                                               size_t used,
+                                               uint allocationContext) {
+  EventG1HeapRegionTypeChange e;
+  if (e.should_commit()) {
+    e.set_index(index);
+    e.set_from(from);
+    e.set_to(to);
+    e.set_start(start);
+    e.set_used(used);
+    e.set_allocContext(allocationContext);
+    e.commit();
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/heapRegionTracer.hpp	Fri Feb 12 09:19:10 2016 +0100
@@ -0,0 +1,41 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_HEAPREGIONTRACER_HPP
+#define SHARE_VM_GC_G1_HEAPREGIONTRACER_HPP
+
+#include "gc/g1/g1HeapRegionTraceType.hpp"
+#include "memory/allocation.hpp"
+
+class HeapRegionTracer : AllStatic {
+  public:
+    static void send_region_type_change(uint index,
+                                        G1HeapRegionTraceType::Type from,
+                                        G1HeapRegionTraceType::Type to,
+                                        uintptr_t start,
+                                        size_t used,
+                                        uint allocationContext);
+};
+
+#endif // SHARE_VM_GC_G1_HEAPREGIONTRACER_HPP

--- a/hotspot/src/share/vm/gc/g1/heapRegionType.cpp	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/heapRegionType.cpp	Fri Feb 12 09:19:10 2016 +0100
@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc/g1/g1HeapRegionTraceType.hpp"
 #include "gc/g1/heapRegionType.hpp"
 
 bool HeapRegionType::is_valid(Tag tag) {
@@ -70,3 +71,19 @@
   // keep some compilers happy
   return NULL;
 }
+
+G1HeapRegionTraceType::Type HeapRegionType::get_trace_type() {
+  hrt_assert_is_valid(_tag);
+  switch (_tag) {
+    case FreeTag:               return G1HeapRegionTraceType::Free;
+    case EdenTag:               return G1HeapRegionTraceType::Eden;
+    case SurvTag:               return G1HeapRegionTraceType::Survivor;
+    case StartsHumongousTag:    return G1HeapRegionTraceType::StartsHumongous;
+    case ContinuesHumongousTag: return G1HeapRegionTraceType::ContinuesHumongous;
+    case OldTag:                return G1HeapRegionTraceType::Old;
+    case ArchiveTag:            return G1HeapRegionTraceType::Archive;
+  }
+  ShouldNotReachHere();
+  // keep some compilers happy
+  return G1HeapRegionTraceType::Free;
+}

--- a/hotspot/src/share/vm/gc/g1/heapRegionType.hpp	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/heapRegionType.hpp	Fri Feb 12 09:19:10 2016 +0100
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
 #define SHARE_VM_GC_G1_HEAPREGIONTYPE_HPP
 
+#include "gc/g1/g1HeapRegionTraceType.hpp"
 #include "memory/allocation.hpp"
 
 #define hrt_assert_is_valid(tag) \
@@ -141,6 +142,7 @@
 
   const char* get_str() const;
   const char* get_short_str() const;
+  G1HeapRegionTraceType::Type get_trace_type();
 
   HeapRegionType() : _tag(FreeTag) { hrt_assert_is_valid(_tag); }
 };

--- a/hotspot/src/share/vm/trace/trace.xml	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/trace/trace.xml	Fri Feb 12 09:19:10 2016 +0100
@@ -486,6 +486,16 @@
       <value type="BYTES64" field="size" label="Size" />
     </event>
 
+    <event id="G1HeapRegionTypeChange" path="vm/gc/detailed/g1_heap_region_type_change" label="G1 Heap Region Type Change"
+           description="Information about a G1 heap region type change." is_instant="true">
+      <value type="UINT" field="index" label="Index" />
+      <value type="G1HEAPREGIONTYPE" field="from" label="From Type" />
+      <value type="G1HEAPREGIONTYPE" field="to" label="To Type" />
+      <value type="ADDRESS" field="start" label="Start" />
+      <value type="BYTES64" field="used" label="Used" />
+      <value type="UINT" field="allocContext" label="Allocation Context" />
+    </event>
+
     <!-- Compiler events -->
 
     <event id="Compilation" path="vm/compiler/compilation" label="Compilation"

--- a/hotspot/src/share/vm/trace/tracetypes.xml	Fri Feb 12 09:12:12 2016 +0100
+++ b/hotspot/src/share/vm/trace/tracetypes.xml	Fri Feb 12 09:19:10 2016 +0100
@@ -126,6 +126,11 @@
       <value type="UTF8" field="when" label="when" />
     </content_type>
 
+    <content_type id="G1HeapRegionType" hr_name="G1 Heap Region Type"
+                  type="U1" jvm_type="G1HEAPREGIONTYPE">
+      <value type="UTF8" field="type" label="type" />
+    </content_type>
+    
     <content_type id="G1YCType" hr_name="G1 YC Type"
                   type="U1" jvm_type="G1YCTYPE">
       <value type="UTF8" field="type" label="type" />
@@ -345,6 +350,10 @@
     <primary_type symbol="GCWHEN" datatype="U1" contenttype="GCWHEN"
                   type="u1" sizeop="sizeof(u1)" />
 
+    <!-- G1HEAPREGIONTYPE -->
+    <primary_type symbol="G1HEAPREGIONTYPE" datatype="U1" contenttype="G1HEAPREGIONTYPE"
+                  type="u1" sizeop="sizeof(u1)" />
+
     <!-- G1YCType -->
     <primary_type symbol="G1YCTYPE" datatype="U1" contenttype="G1YCTYPE"
                   type="u1" sizeop="sizeof(u1)" />