7032531: G1: enhance GC logging to include more accurate eden / survivor size transitions

Summary: This changeset extends the logging information generated by +PrintGCDetails to also print out separate size transitions for the eden, survivors, and old regions.
Reviewed-by: ysr, brutisso

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -3456,6 +3456,8 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
           }
         }
       }
+      // We have to do this after we decide whether to expand the heap or not.
+      g1_policy()->print_heap_transition();
 
       if (mark_in_progress()) {
         concurrent_mark()->update_g1_committed();

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -103,6 +103,19 @@ public:
   size_t       length() { return _length; }
   size_t       survivor_length() { return _survivor_length; }
 
+  // Currently we do not keep track of the used byte sum for the
+  // young list and the survivors and it'd be quite a lot of work to
+  // do so. When we'll eventually replace the young list with
+  // instances of HeapRegionLinkedList we'll get that for free. So,
+  // we'll report the more accurate information then.
+  size_t       eden_used_bytes() {
+    assert(length() >= survivor_length(), "invariant");
+    return (length() - survivor_length()) * HeapRegion::GrainBytes;
+  }
+  size_t       survivor_used_bytes() {
+    return survivor_length() * HeapRegion::GrainBytes;
+  }
+
   void rs_length_sampling_init();
   bool rs_length_sampling_more();
   void rs_length_sampling_next();

src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp

@@ -239,6 +239,10 @@ G1CollectorPolicy::G1CollectorPolicy() :
   _should_revert_to_full_young_gcs(false),
   _last_full_young_gc(false),
 
+  _eden_bytes_before_gc(0),
+  _survivor_bytes_before_gc(0),
+  _capacity_before_gc(0),
+
   _prev_collection_pause_used_at_end_bytes(0),
 
   _collection_set(NULL),
@@ -897,6 +901,11 @@ void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
   _bytes_in_to_space_after_gc = 0;
   _bytes_in_collection_set_before_gc = 0;
 
+  YoungList* young_list = _g1->young_list();
+  _eden_bytes_before_gc = young_list->eden_used_bytes();
+  _survivor_bytes_before_gc = young_list->survivor_used_bytes();
+  _capacity_before_gc = _g1->capacity();
+
 #ifdef DEBUG
   // initialise these to something well known so that we can spot
   // if they are not set properly
@@ -1460,14 +1469,6 @@ void G1CollectorPolicy::record_collection_pause_end() {
       }
     }
   }
-  if (PrintGCDetails)
-    gclog_or_tty->print("   [");
-  if (PrintGC || PrintGCDetails)
-    _g1->print_size_transition(gclog_or_tty,
-                               _cur_collection_pause_used_at_start_bytes,
-                               _g1->used(), _g1->capacity());
-  if (PrintGCDetails)
-    gclog_or_tty->print_cr("]");
 
   _all_pause_times_ms->add(elapsed_ms);
   if (update_stats) {
@@ -1672,6 +1673,40 @@ void G1CollectorPolicy::record_collection_pause_end() {
   // </NEW PREDICTION>
 }
 
+#define EXT_SIZE_FORMAT "%d%s"
+#define EXT_SIZE_PARAMS(bytes)                                  \
+  byte_size_in_proper_unit((bytes)),                            \
+  proper_unit_for_byte_size((bytes))
+
+void G1CollectorPolicy::print_heap_transition() {
+  if (PrintGCDetails) {
+    YoungList* young_list = _g1->young_list();
+    size_t eden_bytes = young_list->eden_used_bytes();
+    size_t survivor_bytes = young_list->survivor_used_bytes();
+    size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
+    size_t used = _g1->used();
+    size_t capacity = _g1->capacity();
+
+    gclog_or_tty->print_cr(
+         "   [Eden: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
+             "Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
+             "Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
+                     EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
+             EXT_SIZE_PARAMS(_eden_bytes_before_gc),
+               EXT_SIZE_PARAMS(eden_bytes),
+             EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
+               EXT_SIZE_PARAMS(survivor_bytes),
+             EXT_SIZE_PARAMS(used_before_gc),
+             EXT_SIZE_PARAMS(_capacity_before_gc),
+               EXT_SIZE_PARAMS(used),
+               EXT_SIZE_PARAMS(capacity));
+  } else if (PrintGC) {
+    _g1->print_size_transition(gclog_or_tty,
+                               _cur_collection_pause_used_at_start_bytes,
+                               _g1->used(), _g1->capacity());
+  }
+}
+
 // <NEW PREDICTION>
 
 void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp

@@ -891,6 +891,7 @@ public:
   virtual void record_collection_pause_end_G1_strong_roots();
 
   virtual void record_collection_pause_end();
+  void print_heap_transition();
 
   // Record the fact that a full collection occurred.
   virtual void record_full_collection_start();
@@ -1179,6 +1180,11 @@ protected:
   // The limit on the number of regions allocated for survivors.
   size_t _max_survivor_regions;
 
+  // For reporting purposes.
+  size_t _eden_bytes_before_gc;
+  size_t _survivor_bytes_before_gc;
+  size_t _capacity_before_gc;
+
   // The amount of survor regions after a collection.
   size_t _recorded_survivor_regions;
   // List of survivor regions.