Mercurial > hg > truffle
diff src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @ 526:818efdefcc99
6484956: G1: improve evacuation pause efficiency
Summary: A bunch of performance optimizations to decrease GC pause times in G1.
Reviewed-by: apetrusenko, jmasa, iveresov
author | tonyp |
---|---|
date | Fri, 16 Jan 2009 13:02:20 -0500 |
parents | 65de26b5ea82 |
children | 58054a18d735 |
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--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Wed Jan 14 14:12:55 2009 -0800 +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp Fri Jan 16 13:02:20 2009 -0500 @@ -247,6 +247,27 @@ NumberSeq _pop_obj_rc_at_copy; void print_popularity_summary_info() const; + // This is used for a quick test on whether a reference points into + // the collection set or not. Basically, we have an array, with one + // byte per region, and that byte denotes whether the corresponding + // region is in the collection set or not. The entry corresponding + // the bottom of the heap, i.e., region 0, is pointed to by + // _in_cset_fast_test_base. The _in_cset_fast_test field has been + // biased so that it actually points to address 0 of the address + // space, to make the test as fast as possible (we can simply shift + // the address to address into it, instead of having to subtract the + // bottom of the heap from the address before shifting it; basically + // it works in the same way the card table works). + bool* _in_cset_fast_test; + + // The allocated array used for the fast test on whether a reference + // points into the collection set or not. This field is also used to + // free the array. + bool* _in_cset_fast_test_base; + + // The length of the _in_cset_fast_test_base array. + size_t _in_cset_fast_test_length; + volatile unsigned _gc_time_stamp; size_t* _surviving_young_words; @@ -368,6 +389,38 @@ virtual void gc_prologue(bool full); virtual void gc_epilogue(bool full); + // We register a region with the fast "in collection set" test. We + // simply set to true the array slot corresponding to this region. + void register_region_with_in_cset_fast_test(HeapRegion* r) { + assert(_in_cset_fast_test_base != NULL, "sanity"); + assert(r->in_collection_set(), "invariant"); + int index = r->hrs_index(); + assert(0 <= (size_t) index && (size_t) index < _in_cset_fast_test_length, + "invariant"); + assert(!_in_cset_fast_test_base[index], "invariant"); + _in_cset_fast_test_base[index] = true; + } + + // This is a fast test on whether a reference points into the + // collection set or not. It does not assume that the reference + // points into the heap; if it doesn't, it will return false. + bool in_cset_fast_test(oop obj) { + assert(_in_cset_fast_test != NULL, "sanity"); + if (_g1_committed.contains((HeapWord*) obj)) { + // no need to subtract the bottom of the heap from obj, + // _in_cset_fast_test is biased + size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes; + bool ret = _in_cset_fast_test[index]; + // let's make sure the result is consistent with what the slower + // test returns + assert( ret || !obj_in_cs(obj), "sanity"); + assert(!ret || obj_in_cs(obj), "sanity"); + return ret; + } else { + return false; + } + } + protected: // Shrink the garbage-first heap by at most the given size (in bytes!).