49 _page_type(page_type),
50 _page_size(page_size),
51 _object_size_limit(object_size_limit),
52 _fragmentation_limit(page_size * (ZFragmentationLimit / 100)),
53 _registered_pages(),
54 _sorted_pages(NULL),
55 _nselected(0),
56 _stats() {}
57
58 ZRelocationSetSelectorGroup::~ZRelocationSetSelectorGroup() {
59 FREE_C_HEAP_ARRAY(ZPage*, _sorted_pages);
60 }
61
62 void ZRelocationSetSelectorGroup::register_live_page(ZPage* page) {
63 const uint8_t type = page->type();
64 const size_t size = page->size();
65 const size_t live = page->live_bytes();
66 const size_t garbage = size - live;
67
68 if (garbage > _fragmentation_limit) {
69 _registered_pages.add(page);
70 }
71
72 _stats._npages++;
73 _stats._total += size;
74 _stats._live += live;
75 _stats._garbage += garbage;
76 }
77
78 void ZRelocationSetSelectorGroup::register_garbage_page(ZPage* page) {
79 const size_t size = page->size();
80
81 _stats._npages++;
82 _stats._total += size;
83 _stats._garbage += size;
84 _stats._empty += size;
85 }
86
87 bool ZRelocationSetSelectorGroup::is_disabled() {
88 // Medium pages are disabled when their page size is zero
89 return _page_type == ZPageTypeMedium && _page_size == 0;
90 }
91
92 bool ZRelocationSetSelectorGroup::is_selectable() {
93 // Large pages are not selectable
94 return _page_type != ZPageTypeLarge;
95 }
96
97 void ZRelocationSetSelectorGroup::semi_sort() {
98 // Semi-sort registered pages by live bytes in ascending order
99 const size_t npartitions_shift = 11;
100 const size_t npartitions = (size_t)1 << npartitions_shift;
101 const size_t partition_size = _page_size >> npartitions_shift;
102 const size_t partition_size_shift = exact_log2(partition_size);
103 const size_t npages = _registered_pages.size();
104
105 // Partition slots/fingers
106 size_t partitions[npartitions];
107
108 // Allocate destination array
109 assert(_sorted_pages == NULL, "Already initialized");
110 _sorted_pages = NEW_C_HEAP_ARRAY(ZPage*, npages, mtGC);
111 debug_only(memset(_sorted_pages, 0, npages * sizeof(ZPage*)));
112
113 // Calculate partition slots
114 memset(partitions, 0, sizeof(partitions));
115 ZArrayIterator<ZPage*> iter1(&_registered_pages);
116 for (ZPage* page; iter1.next(&page);) {
117 const size_t index = page->live_bytes() >> partition_size_shift;
118 partitions[index]++;
119 }
120
121 // Calculate partition fingers
122 size_t finger = 0;
123 for (size_t i = 0; i < npartitions; i++) {
124 const size_t slots = partitions[i];
125 partitions[i] = finger;
126 finger += slots;
127 }
128
129 // Sort pages into partitions
130 ZArrayIterator<ZPage*> iter2(&_registered_pages);
131 for (ZPage* page; iter2.next(&page);) {
132 const size_t index = page->live_bytes() >> partition_size_shift;
133 const size_t finger = partitions[index]++;
134 assert(_sorted_pages[finger] == NULL, "Invalid finger");
135 _sorted_pages[finger] = page;
136 }
137 }
138
139 void ZRelocationSetSelectorGroup::select_inner() {
140 // Calculate the number of pages to relocate by successively including pages in
141 // a candidate relocation set and calculate the maximum space requirement for
142 // their live objects.
143 const size_t npages = _registered_pages.size();
144 size_t selected_from = 0;
145 size_t selected_to = 0;
146 size_t from_size = 0;
147
148 semi_sort();
149
150 for (size_t from = 1; from <= npages; from++) {
151 // Add page to the candidate relocation set
152 from_size += _sorted_pages[from - 1]->live_bytes();
153
154 // Calculate the maximum number of pages needed by the candidate relocation set.
155 // By subtracting the object size limit from the pages size we get the maximum
156 // number of pages that the relocation set is guaranteed to fit in, regardless
157 // of in which order the objects are relocated.
158 const size_t to = ceil((double)(from_size) / (double)(_page_size - _object_size_limit));
159
160 // Calculate the relative difference in reclaimable space compared to our
161 // currently selected final relocation set. If this number is larger than the
162 // acceptable fragmentation limit, then the current candidate relocation set
163 // becomes our new final relocation set.
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49 _page_type(page_type),
50 _page_size(page_size),
51 _object_size_limit(object_size_limit),
52 _fragmentation_limit(page_size * (ZFragmentationLimit / 100)),
53 _registered_pages(),
54 _sorted_pages(NULL),
55 _nselected(0),
56 _stats() {}
57
58 ZRelocationSetSelectorGroup::~ZRelocationSetSelectorGroup() {
59 FREE_C_HEAP_ARRAY(ZPage*, _sorted_pages);
60 }
61
62 void ZRelocationSetSelectorGroup::register_live_page(ZPage* page) {
63 const uint8_t type = page->type();
64 const size_t size = page->size();
65 const size_t live = page->live_bytes();
66 const size_t garbage = size - live;
67
68 if (garbage > _fragmentation_limit) {
69 _registered_pages.append(page);
70 }
71
72 _stats._npages++;
73 _stats._total += size;
74 _stats._live += live;
75 _stats._garbage += garbage;
76 }
77
78 void ZRelocationSetSelectorGroup::register_garbage_page(ZPage* page) {
79 const size_t size = page->size();
80
81 _stats._npages++;
82 _stats._total += size;
83 _stats._garbage += size;
84 _stats._empty += size;
85 }
86
87 bool ZRelocationSetSelectorGroup::is_disabled() {
88 // Medium pages are disabled when their page size is zero
89 return _page_type == ZPageTypeMedium && _page_size == 0;
90 }
91
92 bool ZRelocationSetSelectorGroup::is_selectable() {
93 // Large pages are not selectable
94 return _page_type != ZPageTypeLarge;
95 }
96
97 void ZRelocationSetSelectorGroup::semi_sort() {
98 // Semi-sort registered pages by live bytes in ascending order
99 const size_t npartitions_shift = 11;
100 const size_t npartitions = (size_t)1 << npartitions_shift;
101 const size_t partition_size = _page_size >> npartitions_shift;
102 const size_t partition_size_shift = exact_log2(partition_size);
103 const size_t npages = _registered_pages.length();
104
105 // Partition slots/fingers
106 size_t partitions[npartitions];
107
108 // Allocate destination array
109 assert(_sorted_pages == NULL, "Already initialized");
110 _sorted_pages = NEW_C_HEAP_ARRAY(ZPage*, npages, mtGC);
111 debug_only(memset(_sorted_pages, 0, npages * sizeof(ZPage*)));
112
113 // Calculate partition slots
114 memset(partitions, 0, sizeof(partitions));
115 ZArrayIterator<ZPage*> iter1(&_registered_pages);
116 for (ZPage* page; iter1.next(&page);) {
117 const size_t index = page->live_bytes() >> partition_size_shift;
118 partitions[index]++;
119 }
120
121 // Calculate partition fingers
122 size_t finger = 0;
123 for (size_t i = 0; i < npartitions; i++) {
124 const size_t slots = partitions[i];
125 partitions[i] = finger;
126 finger += slots;
127 }
128
129 // Sort pages into partitions
130 ZArrayIterator<ZPage*> iter2(&_registered_pages);
131 for (ZPage* page; iter2.next(&page);) {
132 const size_t index = page->live_bytes() >> partition_size_shift;
133 const size_t finger = partitions[index]++;
134 assert(_sorted_pages[finger] == NULL, "Invalid finger");
135 _sorted_pages[finger] = page;
136 }
137 }
138
139 void ZRelocationSetSelectorGroup::select_inner() {
140 // Calculate the number of pages to relocate by successively including pages in
141 // a candidate relocation set and calculate the maximum space requirement for
142 // their live objects.
143 const size_t npages = _registered_pages.length();
144 size_t selected_from = 0;
145 size_t selected_to = 0;
146 size_t from_size = 0;
147
148 semi_sort();
149
150 for (size_t from = 1; from <= npages; from++) {
151 // Add page to the candidate relocation set
152 from_size += _sorted_pages[from - 1]->live_bytes();
153
154 // Calculate the maximum number of pages needed by the candidate relocation set.
155 // By subtracting the object size limit from the pages size we get the maximum
156 // number of pages that the relocation set is guaranteed to fit in, regardless
157 // of in which order the objects are relocated.
158 const size_t to = ceil((double)(from_size) / (double)(_page_size - _object_size_limit));
159
160 // Calculate the relative difference in reclaimable space compared to our
161 // currently selected final relocation set. If this number is larger than the
162 // acceptable fragmentation limit, then the current candidate relocation set
163 // becomes our new final relocation set.
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