--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Mon Jan 16 22:10:05 2012 +0100
@@ -1045,17 +1045,24 @@
       // regions, we'll first try to do the allocation without doing a
       // collection hoping that there's enough space in the heap.
       result = humongous_obj_allocate(word_size);
-      if (result != NULL) {
-        return result;
+
+      if (result == NULL) {
+        if (GC_locker::is_active_and_needs_gc()) {
+          should_try_gc = false;
+        } else {
+          // Read the GC count while still holding the Heap_lock.
+          gc_count_before = SharedHeap::heap()->total_collections();
+          should_try_gc = true;
+        }
       }
-
-      if (GC_locker::is_active_and_needs_gc()) {
-        should_try_gc = false;
-      } else {
-        // Read the GC count while still holding the Heap_lock.
-        gc_count_before = SharedHeap::heap()->total_collections();
-        should_try_gc = true;
+    }
+
+    if (result != NULL) {
+      if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation")) {
+        // We need to release the Heap_lock before we try to call collect
+        collect(GCCause::_g1_humongous_allocation);
       }
+      return result;
     }
 
     if (should_try_gc) {
@@ -1111,7 +1118,11 @@
     return _mutator_alloc_region.attempt_allocation_locked(word_size,
                                                       false /* bot_updates */);
   } else {
-    return humongous_obj_allocate(word_size);
+    HeapWord* result = humongous_obj_allocate(word_size);
+    if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
+      g1_policy()->set_initiate_conc_mark_if_possible();
+    }
+    return result;
   }
 
   ShouldNotReachHere();
@@ -2295,7 +2306,8 @@
 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
   return
     ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
-     (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
+     (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent) ||
+      cause == GCCause::_g1_humongous_allocation);
 }
 
 #ifndef PRODUCT

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Mon Jan 16 22:10:05 2012 +0100
@@ -355,6 +355,7 @@
   // explicitly started if:
   // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
   // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
+  // (c) cause == _g1_humongous_allocation
   bool should_do_concurrent_full_gc(GCCause::Cause cause);
 
   // Keeps track of how many "full collections" (i.e., Full GCs or
@@ -1172,6 +1173,10 @@
     _old_set.remove(hr);
   }
 
+  size_t non_young_capacity_bytes() {
+    return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
+  }
+
   void set_free_regions_coming();
   void reset_free_regions_coming();
   bool free_regions_coming() { return _free_regions_coming; }

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Mon Jan 16 22:10:05 2012 +0100
@@ -213,8 +213,6 @@
   _survivor_bytes_before_gc(0),
   _capacity_before_gc(0),
 
-  _prev_collection_pause_used_at_end_bytes(0),
-
   _eden_cset_region_length(0),
   _survivor_cset_region_length(0),
   _old_cset_region_length(0),
@@ -1140,6 +1138,45 @@
   return ret;
 }
 
+bool G1CollectorPolicy::need_to_start_conc_mark(const char* source) {
+  if (_g1->mark_in_progress()) {
+    return false;
+  }
+
+  size_t marking_initiating_used_threshold =
+    (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
+  size_t cur_used_bytes = _g1->non_young_capacity_bytes();
+
+  if (cur_used_bytes > marking_initiating_used_threshold) {
+    if (gcs_are_young()) {
+      ergo_verbose4(ErgoConcCycles,
+        "request concurrent cycle initiation",
+        ergo_format_reason("occupancy higher than threshold")
+        ergo_format_byte("occupancy")
+        ergo_format_byte_perc("threshold")
+        ergo_format_str("source"),
+        cur_used_bytes,
+        marking_initiating_used_threshold,
+        (double) InitiatingHeapOccupancyPercent,
+        source);
+      return true;
+    } else {
+      ergo_verbose4(ErgoConcCycles,
+        "do not request concurrent cycle initiation",
+        ergo_format_reason("still doing mixed collections")
+        ergo_format_byte("occupancy")
+        ergo_format_byte_perc("threshold")
+        ergo_format_str("source"),
+        cur_used_bytes,
+        marking_initiating_used_threshold,
+        (double) InitiatingHeapOccupancyPercent,
+        source);
+    }
+  }
+
+  return false;
+}
+
 // Anything below that is considered to be zero
 #define MIN_TIMER_GRANULARITY 0.0000001
 
@@ -1166,44 +1203,16 @@
 #endif // PRODUCT
 
   last_pause_included_initial_mark = during_initial_mark_pause();
-  if (last_pause_included_initial_mark)
+  if (last_pause_included_initial_mark) {
     record_concurrent_mark_init_end(0.0);
-
-  size_t marking_initiating_used_threshold =
-    (_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
-
-  if (!_g1->mark_in_progress() && !_last_young_gc) {
-    assert(!last_pause_included_initial_mark, "invariant");
-    if (cur_used_bytes > marking_initiating_used_threshold) {
-      if (cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
-        assert(!during_initial_mark_pause(), "we should not see this here");
-
-        ergo_verbose3(ErgoConcCycles,
-                      "request concurrent cycle initiation",
-                      ergo_format_reason("occupancy higher than threshold")
-                      ergo_format_byte("occupancy")
-                      ergo_format_byte_perc("threshold"),
-                      cur_used_bytes,
-                      marking_initiating_used_threshold,
-                      (double) InitiatingHeapOccupancyPercent);
-
-        // Note: this might have already been set, if during the last
-        // pause we decided to start a cycle but at the beginning of
-        // this pause we decided to postpone it. That's OK.
-        set_initiate_conc_mark_if_possible();
-      } else {
-        ergo_verbose2(ErgoConcCycles,
-                  "do not request concurrent cycle initiation",
-                  ergo_format_reason("occupancy lower than previous occupancy")
-                  ergo_format_byte("occupancy")
-                  ergo_format_byte("previous occupancy"),
-                  cur_used_bytes,
-                  _prev_collection_pause_used_at_end_bytes);
-      }
-    }
   }
 
-  _prev_collection_pause_used_at_end_bytes = cur_used_bytes;
+  if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
+    // Note: this might have already been set, if during the last
+    // pause we decided to start a cycle but at the beginning of
+    // this pause we decided to postpone it. That's OK.
+    set_initiate_conc_mark_if_possible();
+  }
 
   _mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
                           end_time_sec, false);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp	Mon Jan 16 22:10:05 2012 +0100
@@ -177,7 +177,6 @@
   double _cur_collection_start_sec;
   size_t _cur_collection_pause_used_at_start_bytes;
   size_t _cur_collection_pause_used_regions_at_start;
-  size_t _prev_collection_pause_used_at_end_bytes;
   double _cur_collection_par_time_ms;
   double _cur_satb_drain_time_ms;
   double _cur_clear_ct_time_ms;
@@ -800,6 +799,8 @@
 
   GenRemSet::Name  rem_set_name()     { return GenRemSet::CardTable; }
 
+  bool need_to_start_conc_mark(const char* source);
+
   // Update the heuristic info to record a collection pause of the given
   // start time, where the given number of bytes were used at the start.
   // This may involve changing the desired size of a collection set.

--- a/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp	Mon Jan 16 22:10:05 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, 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
@@ -74,8 +74,9 @@
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   assert(!_should_initiate_conc_mark ||
   ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
-   (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
-         "only a GC locker or a System.gc() induced GC should start a cycle");
+   (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent) ||
+    _gc_cause == GCCause::_g1_humongous_allocation),
+         "only a GC locker, a System.gc() or a hum allocation induced GC should start a cycle");
 
   if (_word_size > 0) {
     // An allocation has been requested. So, try to do that first.

--- a/hotspot/src/share/vm/gc_interface/gcCause.cpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_interface/gcCause.cpp	Mon Jan 16 22:10:05 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, 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
@@ -84,6 +84,9 @@
     case _g1_inc_collection_pause:
       return "G1 Evacuation Pause";
 
+    case _g1_humongous_allocation:
+      return "G1 Humongous Allocation";
+
     case _last_ditch_collection:
       return "Last ditch collection";
 

--- a/hotspot/src/share/vm/gc_interface/gcCause.hpp	Mon Jan 16 11:21:21 2012 +0100
+++ b/hotspot/src/share/vm/gc_interface/gcCause.hpp	Mon Jan 16 22:10:05 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, 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
@@ -66,6 +66,7 @@
     _adaptive_size_policy,
 
     _g1_inc_collection_pause,
+    _g1_humongous_allocation,
 
     _last_ditch_collection,
     _last_gc_cause