--- a/hotspot/src/share/vm/gc/g1/g1AllocRegion.cpp	Mon Mar 21 15:59:58 2016 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1AllocRegion.cpp	Tue Mar 22 13:41:52 2016 +0100
@@ -26,6 +26,7 @@
 #include "gc/g1/g1AllocRegion.inline.hpp"
 #include "gc/g1/g1EvacStats.inline.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "memory/resourceArea.hpp"
 #include "runtime/orderAccess.inline.hpp"
 
 G1CollectedHeap* G1AllocRegion::_g1h = NULL;
@@ -194,44 +195,53 @@
   return (alloc_region == _dummy_region) ? NULL : alloc_region;
 }
 
-#if G1_ALLOC_REGION_TRACING
+#ifndef PRODUCT
 void G1AllocRegion::trace(const char* str, size_t min_word_size, size_t desired_word_size, size_t actual_word_size, HeapWord* result) {
   // All the calls to trace that set either just the size or the size
-  // and the result are considered part of level 2 tracing and are
-  // skipped during level 1 tracing.
-  if ((actual_word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {
-    const size_t buffer_length = 128;
-    char hr_buffer[buffer_length];
-    char rest_buffer[buffer_length];
+  // and the result are considered part of detailed tracing and are
+  // skipped during other tracing.
+
+  LogHandle(gc, alloc, region) log;
+
+  if (!log.is_debug()) {
+    return;
+  }
 
-    HeapRegion* alloc_region = _alloc_region;
-    if (alloc_region == NULL) {
-      jio_snprintf(hr_buffer, buffer_length, "NULL");
-    } else if (alloc_region == _dummy_region) {
-      jio_snprintf(hr_buffer, buffer_length, "DUMMY");
+  bool detailed_info = log.is_trace();
+
+  if ((actual_word_size == 0 && result == NULL) || detailed_info) {
+    ResourceMark rm;
+    outputStream* out;
+    if (detailed_info) {
+      out = log.trace_stream();
     } else {
-      jio_snprintf(hr_buffer, buffer_length,
-                   HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));
+      out = log.debug_stream();
     }
 
-    if (G1_ALLOC_REGION_TRACING > 1) {
-      if (result != NULL) {
-        jio_snprintf(rest_buffer, buffer_length, "min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
-                     min_word_size, desired_word_size, actual_word_size, result);
-      } else if (min_word_size != 0) {
-        jio_snprintf(rest_buffer, buffer_length, "min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
-      } else {
-        jio_snprintf(rest_buffer, buffer_length, "");
-      }
+    out->print("%s: %u ", _name, _count);
+
+    if (_alloc_region == NULL) {
+      out->print("NULL");
+    } else if (_alloc_region == _dummy_region) {
+      out->print("DUMMY");
     } else {
-      jio_snprintf(rest_buffer, buffer_length, "");
+      out->print(HR_FORMAT, HR_FORMAT_PARAMS(_alloc_region));
     }
 
-    tty->print_cr("[%s] %u %s : %s %s",
-                  _name, _count, hr_buffer, str, rest_buffer);
+    out->print(" : %s", str);
+
+    if (detailed_info) {
+      if (result != NULL) {
+        out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
+                     min_word_size, desired_word_size, actual_word_size, p2i(result));
+      } else if (min_word_size != 0) {
+        out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
+      }
+    }
+    out->cr();
   }
 }
-#endif // G1_ALLOC_REGION_TRACING
+#endif // PRODUCT
 
 G1AllocRegion::G1AllocRegion(const char* name,
                              bool bot_updates)

--- a/hotspot/src/share/vm/gc/g1/g1AllocRegion.hpp	Mon Mar 21 15:59:58 2016 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1AllocRegion.hpp	Tue Mar 22 13:41:52 2016 +0100
@@ -31,9 +31,6 @@
 
 class G1CollectedHeap;
 
-// 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
-#define G1_ALLOC_REGION_TRACING 0
-
 // A class that holds a region that is active in satisfying allocation
 // requests, potentially issued in parallel. When the active region is
 // full it will be retired and replaced with a new one. The
@@ -213,19 +210,11 @@
   // is returned after it's been retired.
   virtual HeapRegion* release();
 
-#if G1_ALLOC_REGION_TRACING
   void trace(const char* str,
              size_t min_word_size = 0,
              size_t desired_word_size = 0,
              size_t actual_word_size = 0,
-             HeapWord* result = NULL);
-#else // G1_ALLOC_REGION_TRACING
-  void trace(const char* str,
-             size_t min_word_size = 0,
-             size_t desired_word_size = 0,
-             size_t actual_word_size = 0,
-             HeapWord* result = NULL) { }
-#endif // G1_ALLOC_REGION_TRACING
+             HeapWord* result = NULL) PRODUCT_RETURN;
 };
 
 class MutatorAllocRegion : public G1AllocRegion {

--- a/hotspot/src/share/vm/logging/logPrefix.hpp	Mon Mar 21 15:59:58 2016 -0400
+++ b/hotspot/src/share/vm/logging/logPrefix.hpp	Tue Mar 22 13:41:52 2016 +0100
@@ -42,6 +42,7 @@
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc)) \
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, age)) \
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, alloc)) \
+  LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, alloc, region)) \
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, barrier)) \
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, classhisto)) \
   LOG_PREFIX(GCId::print_prefix, LOG_TAGS(gc, compaction)) \