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diff src/share/vm/gc_implementation/g1/heapRegion.cpp @ 6611:7383557659bd

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7185699: G1: Prediction model discrepancies Summary: Correct the result value of G1CollectedHeap::pending_card_num(). Change the code that calculates the GC efficiency of a non-young heap region to use historical data from mixed GCs and the actual number of live bytes when predicting how long it would take to collect the region. Changes were also reviewed by Thomas Schatzl. Reviewed-by: azeemj, brutisso
author johnc
date Tue, 21 Aug 2012 14:10:39 -0700
parents a2f7274eb6ef
children c38f13903fdf da91efe96a93
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--- a/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Aug 21 10:05:57 2012 -0700
+++ b/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Aug 21 14:10:39 2012 -0700
@@ -384,10 +384,17 @@
 }
 
 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);
+
+  // Retrieve a prediction of the elapsed time for this region for
+  // a mixed gc because the region will only be evacuated during a
+  // mixed gc.
+  double region_elapsed_time_ms =
+    g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
+  _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
 }
 
 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {