--- old/src/share/vm/gc_implementation/g1/heapRegion.cpp	2012-07-24 11:52:17.362811133 -0700
+++ new/src/share/vm/gc_implementation/g1/heapRegion.cpp	2012-07-24 11:52:17.151968457 -0700
@@ -384,10 +384,24 @@
 }
 
 void HeapRegion::calc_gc_efficiency() {
+  // GC efficiency is the ratio of how much space would be
+  // reclaimed over how long we predict it would take to reclaim it.
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   G1CollectorPolicy* g1p = g1h->g1_policy();
-  _gc_efficiency = (double) reclaimable_bytes() /
-                            g1p->predict_region_elapsed_time_ms(this, false);
+
+  // The calculation of how long it would take to collect this region
+  // is based upon G1CollectorPolicy::predict_region_elapsed_time_ms().
+  // If that routine changes, this code should be changed appropriately.
+  size_t rs_length = rem_set()->occupied();
+  size_t card_num = g1p->predict_non_young_card_num(rs_length);
+  size_t bytes_to_copy = live_bytes();
+
+  double region_elapsed_time_ms =
+    g1p->predict_rs_scan_time_ms(card_num) +
+    g1p->predict_object_copy_time_ms(bytes_to_copy)  +
+    g1p->predict_non_young_other_time_ms(1);
+
+  _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 }
 
 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {