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diff src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.hpp @ 20543:e7d0505c8a30

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8059758: Footprint regressions with JDK-8038423 Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything. Reviewed-by: jwilhelm, brutisso
author tschatzl
date Fri, 10 Oct 2014 15:51:58 +0200
parents 7b2fc3129653
children
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line diff
--- a/src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.hpp	Fri Oct 10 15:45:45 2014 +0200
+++ b/src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.hpp	Fri Oct 10 15:51:58 2014 +0200
@@ -33,7 +33,9 @@
  public:
   // Fired after commit of the memory, i.e. the memory this listener is registered
   // for can be accessed.
-  virtual void on_commit(uint start_idx, size_t num_regions) = 0;
+  // Zero_filled indicates that the memory can be considered as filled with zero bytes
+  // when called.
+  virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled) = 0;
 };
 
 // Maps region based commit/uncommit requests to the underlying page sized virtual
@@ -51,7 +53,7 @@
 
   G1RegionToSpaceMapper(ReservedSpace rs, size_t commit_granularity, size_t region_granularity, MemoryType type);
 
-  void fire_on_commit(uint start_idx, size_t num_regions);
+  void fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled);
  public:
   MemRegion reserved() { return _storage.reserved(); }