Thu, 21 Aug 2014 16:44:41 +0200
8055098: WB API should be extended to provide information about size and age of object.
Summary: Extend the WhiteBox API to provide information about the size and age of objects. Further add a mechanism to trigger a young GC.
Reviewed-by: tschatzl, sjohanss
Contributed-by: Leonid Mesnik <leonid.mesnik@oracle.com>
1 /*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 * You should have received a copy of the GNU General Public License version
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
28 #include "gc_implementation/g1/g1_globals.hpp"
29 #include "gc_implementation/g1/g1CardCounts.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/safepoint.hpp"
32 #include "runtime/thread.inline.hpp"
33 #include "utilities/globalDefinitions.hpp"
35 class DirtyCardQueue;
36 class G1CollectedHeap;
37 class G1RemSet;
38 class HeapRegion;
40 // An evicting cache of cards that have been logged by the G1 post
41 // write barrier. Placing a card in the cache delays the refinement
42 // of the card until the card is evicted, or the cache is drained
43 // during the next evacuation pause.
44 //
45 // The first thing the G1 post write barrier does is to check whether
46 // the card containing the updated pointer is already dirty and, if
47 // so, skips the remaining code in the barrier.
48 //
49 // Delaying the refinement of a card will make the card fail the
50 // first is_dirty check in the write barrier, skipping the remainder
51 // of the write barrier.
52 //
53 // This can significantly reduce the overhead of the write barrier
54 // code, increasing throughput.
56 class G1HotCardCache: public CHeapObj<mtGC> {
57 G1CollectedHeap* _g1h;
59 // The card cache table
60 jbyte** _hot_cache;
62 int _hot_cache_size;
63 int _n_hot;
64 int _hot_cache_idx;
66 int _hot_cache_par_chunk_size;
67 volatile int _hot_cache_par_claimed_idx;
69 bool _use_cache;
71 G1CardCounts _card_counts;
73 bool default_use_cache() const {
74 return (G1ConcRSLogCacheSize > 0);
75 }
77 public:
78 G1HotCardCache(G1CollectedHeap* g1h);
79 ~G1HotCardCache();
81 void initialize(G1RegionToSpaceMapper* card_counts_storage);
83 bool use_cache() { return _use_cache; }
85 void set_use_cache(bool b) {
86 _use_cache = (b ? default_use_cache() : false);
87 }
89 // Returns the card to be refined or NULL.
90 //
91 // Increments the count for given the card. if the card is not 'hot',
92 // it is returned for immediate refining. Otherwise the card is
93 // added to the hot card cache.
94 // If there is enough room in the hot card cache for the card we're
95 // adding, NULL is returned and no further action in needed.
96 // If we evict a card from the cache to make room for the new card,
97 // the evicted card is then returned for refinement.
98 jbyte* insert(jbyte* card_ptr);
100 // Refine the cards that have delayed as a result of
101 // being in the cache.
102 void drain(uint worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
104 // Set up for parallel processing of the cards in the hot cache
105 void reset_hot_cache_claimed_index() {
106 _hot_cache_par_claimed_idx = 0;
107 }
109 // Resets the hot card cache and discards the entries.
110 void reset_hot_cache() {
111 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
112 assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread");
113 _hot_cache_idx = 0; _n_hot = 0;
114 }
116 bool hot_cache_is_empty() { return _n_hot == 0; }
118 // Zeros the values in the card counts table for entire committed heap
119 void reset_card_counts();
121 // Zeros the values in the card counts table for the given region
122 void reset_card_counts(HeapRegion* hr);
123 };
125 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP