19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/dirtyCardQueue.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1HotCardCache.hpp"
29 #include "gc_implementation/g1/g1RemSet.hpp"
30 #include "runtime/atomic.inline.hpp"
31
32 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
33 _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
34
35 void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {
36 if (default_use_cache()) {
37 _use_cache = true;
38
39 _hot_cache_size = (1 << G1ConcRSLogCacheSize);
40 _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
41
42 _n_hot = 0;
43 _hot_cache_idx = 0;
44
45 // For refining the cards in the hot cache in parallel
46 _hot_cache_par_chunk_size = ClaimChunkSize;
47 _hot_cache_par_claimed_idx = 0;
48
49 _card_counts.initialize(card_counts_storage);
50 }
51 }
52
53 G1HotCardCache::~G1HotCardCache() {
54 if (default_use_cache()) {
55 assert(_hot_cache != NULL, "Logic");
56 FREE_C_HEAP_ARRAY(jbyte*, _hot_cache);
57 }
58 }
59
60 jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
61 uint count = _card_counts.add_card_count(card_ptr);
62 if (!_card_counts.is_hot(count)) {
63 // The card is not hot so do not store it in the cache;
64 // return it for immediate refining.
65 return card_ptr;
66 }
67
68 // Otherwise, the card is hot.
69 jbyte* res = NULL;
70 MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
71 if (_n_hot == _hot_cache_size) {
72 res = _hot_cache[_hot_cache_idx];
73 _n_hot--;
74 }
75
76 // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
77 _hot_cache[_hot_cache_idx] = card_ptr;
78 _hot_cache_idx++;
79
80 if (_hot_cache_idx == _hot_cache_size) {
81 // Wrap around
82 _hot_cache_idx = 0;
83 }
84 _n_hot++;
85
86 return res;
87 }
88
89 void G1HotCardCache::drain(uint worker_i,
90 G1RemSet* g1rs,
91 DirtyCardQueue* into_cset_dcq) {
92 if (!default_use_cache()) {
93 assert(_hot_cache == NULL, "Logic");
94 return;
95 }
96
97 assert(_hot_cache != NULL, "Logic");
98 assert(!use_cache(), "cache should be disabled");
99 int start_idx;
100
101 while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
102 int end_idx = start_idx + _hot_cache_par_chunk_size;
103
104 if (start_idx ==
105 Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
106 // The current worker has successfully claimed the chunk [start_idx..end_idx)
107 end_idx = MIN2(end_idx, _n_hot);
108 for (int i = start_idx; i < end_idx; i++) {
109 jbyte* card_ptr = _hot_cache[i];
110 if (card_ptr != NULL) {
111 if (g1rs->refine_card(card_ptr, worker_i, true)) {
112 // The part of the heap spanned by the card contains references
113 // that point into the current collection set.
114 // We need to record the card pointer in the DirtyCardQueueSet
115 // that we use for such cards.
116 //
117 // The only time we care about recording cards that contain
118 // references that point into the collection set is during
119 // RSet updating while within an evacuation pause.
120 // In this case worker_i should be the id of a GC worker thread
121 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
122 assert(worker_i < ParallelGCThreads,
123 err_msg("incorrect worker id: %u", worker_i));
124
125 into_cset_dcq->enqueue(card_ptr);
126 }
127 }
128 }
129 }
130 }
131 // The existing entries in the hot card cache, which were just refined
132 // above, are discarded prior to re-enabling the cache near the end of the GC.
133 }
134
135 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
136 _card_counts.clear_region(hr);
137 }
138
139 void G1HotCardCache::reset_card_counts() {
140 _card_counts.clear_all();
141 }
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/dirtyCardQueue.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1HotCardCache.hpp"
29 #include "gc_implementation/g1/g1RemSet.hpp"
30 #include "runtime/atomic.inline.hpp"
31
32 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
33 _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
34
35 void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {
36 if (default_use_cache()) {
37 _use_cache = true;
38
39 _hot_cache_size = (size_t)1 << G1ConcRSLogCacheSize;
40 _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
41 for (size_t i = 0; i < _hot_cache_size; i++) {
42 _hot_cache[i] = NULL;
43 }
44
45 _hot_cache_idx = 0;
46
47 // For refining the cards in the hot cache in parallel
48 _hot_cache_par_chunk_size = ClaimChunkSize;
49 _hot_cache_par_claimed_idx = 0;
50
51 _card_counts.initialize(card_counts_storage);
52 }
53 }
54
55 G1HotCardCache::~G1HotCardCache() {
56 if (default_use_cache()) {
57 assert(_hot_cache != NULL, "Logic");
58 FREE_C_HEAP_ARRAY(jbyte*, _hot_cache);
59 }
60 }
61
62 jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
63 uint count = _card_counts.add_card_count(card_ptr);
64 if (!_card_counts.is_hot(count)) {
65 // The card is not hot so do not store it in the cache;
66 // return it for immediate refining.
67 return card_ptr;
68 }
69 // Otherwise, the card is hot.
70 size_t index = Atomic::add(1, &_hot_cache_idx) - 1;
71 size_t masked_index = index & (_hot_cache_size - 1);
72 jbyte* current_ptr = _hot_cache[masked_index];
73
74 // Try to store the new card pointer into the cache. Compare-and-swap to guard
75 // against the unlikely event of a race resulting in another card pointer to
76 // have already been written to the cache. In this case we will return
77 // card_ptr in favor of the other option, which would be starting over. This
78 // should be OK since card_ptr will likely be the older card already when/if
79 // this ever happens.
80 jbyte* previous_ptr = (jbyte*)Atomic::cmpxchg_ptr(card_ptr,
81 &_hot_cache[masked_index],
82 current_ptr);
83 return (previous_ptr == current_ptr) ? previous_ptr : card_ptr;
84 }
85
86 void G1HotCardCache::drain(uint worker_i,
87 G1RemSet* g1rs,
88 DirtyCardQueue* into_cset_dcq) {
89 if (!default_use_cache()) {
90 assert(_hot_cache == NULL, "Logic");
91 return;
92 }
93
94 assert(_hot_cache != NULL, "Logic");
95 assert(!use_cache(), "cache should be disabled");
96
97 while (_hot_cache_par_claimed_idx < _hot_cache_size) {
98 size_t end_idx = Atomic::add(_hot_cache_par_chunk_size,
99 &_hot_cache_par_claimed_idx);
100 size_t start_idx = end_idx - _hot_cache_par_chunk_size;
101 // The current worker has successfully claimed the chunk [start_idx..end_idx)
102 end_idx = MIN2(end_idx, _hot_cache_size);
103 for (size_t i = start_idx; i < end_idx; i++) {
104 jbyte* card_ptr = _hot_cache[i];
105 if (card_ptr != NULL) {
106 if (g1rs->refine_card(card_ptr, worker_i, true)) {
107 // The part of the heap spanned by the card contains references
108 // that point into the current collection set.
109 // We need to record the card pointer in the DirtyCardQueueSet
110 // that we use for such cards.
111 //
112 // The only time we care about recording cards that contain
113 // references that point into the collection set is during
114 // RSet updating while within an evacuation pause.
115 // In this case worker_i should be the id of a GC worker thread
116 assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
117 assert(worker_i < ParallelGCThreads,
118 err_msg("incorrect worker id: %u", worker_i));
119
120 into_cset_dcq->enqueue(card_ptr);
121 }
122 } else {
123 break;
124 }
125 }
126 }
127
128 // The existing entries in the hot card cache, which were just refined
129 // above, are discarded prior to re-enabling the cache near the end of the GC.
130 }
131
132 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
133 _card_counts.clear_region(hr);
134 }
135
136 void G1HotCardCache::reset_card_counts() {
137 _card_counts.clear_all();
138 }
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