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6672698: mangle_unused_area() should not remangle the entire heap at each collection

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Maintain a high water mark for the allocations in a space and mangle only up to that high water mark.

Reviewed-by: ysr, apetrusenko
This commit is contained in:
Jon Masamitsu 2008-07-09 15:08:55 -07:00
parent 0d9452401c
commit 18dbebd143
43 changed files with 1299 additions and 206 deletions
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42
hotspot/src/share/vm/gc_implementation/shared/mutableSpace.hpp
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@ -30,14 +30,23 @@
// Invariant: (ImmutableSpace +) bottom() <= top() <= end()
// top() is inclusive and end() is exclusive.
class MutableSpaceMangler;
class MutableSpace: public ImmutableSpace {
friend class VMStructs;
// Helper for mangling unused space in debug builds
MutableSpaceMangler* _mangler;
protected:
HeapWord* _top;
MutableSpaceMangler* mangler() { return _mangler; }
public:
virtual ~MutableSpace() {}
MutableSpace() { _top = NULL; }
virtual ~MutableSpace();
MutableSpace();
// Accessors
HeapWord* top() const { return _top; }
virtual void set_top(HeapWord* value) { _top = value; }
@ -52,21 +61,30 @@ class MutableSpace: public ImmutableSpace {
MemRegion used_region() { return MemRegion(bottom(), top()); }
// Initialization
virtual void initialize(MemRegion mr, bool clear_space);
virtual void clear();
virtual void initialize(MemRegion mr,
bool clear_space,
bool mangle_space);
virtual void clear(bool mangle_space);
// Does the usual initialization but optionally resets top to bottom.
#if 0 // MANGLE_SPACE
void initialize(MemRegion mr, bool clear_space, bool reset_top);
#endif
virtual void update() { }
virtual void accumulate_statistics() { }
// Overwrites the unused portion of this space. Note that some collectors
// may use this "scratch" space during collections.
virtual void mangle_unused_area() {
mangle_region(MemRegion(_top, _end));
}
// Methods used in mangling. See descriptions under SpaceMangler.
virtual void mangle_unused_area() PRODUCT_RETURN;
virtual void mangle_unused_area_complete() PRODUCT_RETURN;
virtual void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
virtual void check_mangled_unused_area_complete() PRODUCT_RETURN;
virtual void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;
// Used to save the space's current top for later use during mangling.
virtual void set_top_for_allocations() PRODUCT_RETURN;
virtual void ensure_parsability() { }
void mangle_region(MemRegion mr) {
debug_only(Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord));
}
virtual void mangle_region(MemRegion mr) PRODUCT_RETURN;
// Boolean querries.
bool is_empty() const { return used_in_words() == 0; }