1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
26 #define SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
27
28 #include "gc/g1/g1BiasedArray.hpp"
29 #include "gc/g1/g1RegionToSpaceMapper.hpp"
30 #include "gc/g1/heapRegionSet.hpp"
31 #include "gc/shared/workgroup.hpp"
32 #include "services/memoryUsage.hpp"
33
34 class HeapRegion;
35 class HeapRegionClosure;
36 class HeapRegionClaimer;
37 class FreeRegionList;
38 class WorkGang;
39
40 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
41 protected:
42 virtual HeapRegion* default_value() const { return NULL; }
43 };
44
45 // This class keeps track of the actual heap memory, auxiliary data
46 // and its metadata (i.e., HeapRegion instances) and the list of free regions.
47 //
48 // This allows maximum flexibility for deciding what to commit or uncommit given
49 // a request from outside.
50 //
51 // HeapRegions are kept in the _regions array in address order. A region's
52 // index in the array corresponds to its index in the heap (i.e., 0 is the
53 // region at the bottom of the heap, 1 is the one after it, etc.). Two
54 // regions that are consecutive in the array should also be adjacent in the
55 // address space (i.e., region(i).end() == region(i+1).bottom().
56 //
57 // We create a HeapRegion when we commit the region's address space
58 // for the first time. When we uncommit the address space of a
59 // region we retain the HeapRegion to be able to re-use it in the
60 // future (in case we recommit it).
61 //
62 // We keep track of three lengths:
63 //
64 // * _num_committed (returned by length()) is the number of currently
65 // committed regions. These may not be contiguous.
66 // * _allocated_heapregions_length (not exposed outside this class) is the
67 // number of regions+1 for which we have HeapRegions.
68 // * max_length() returns the maximum number of regions the heap can have.
69 //
70
71 class HeapRegionManager: public CHeapObj<mtGC> {
72 friend class VMStructs;
73 friend class HeapRegionClaimer;
74
75 G1HeapRegionTable _regions;
76
77 G1RegionToSpaceMapper* _heap_mapper;
78 G1RegionToSpaceMapper* _prev_bitmap_mapper;
79 G1RegionToSpaceMapper* _next_bitmap_mapper;
80 G1RegionToSpaceMapper* _bot_mapper;
81 G1RegionToSpaceMapper* _cardtable_mapper;
82 G1RegionToSpaceMapper* _card_counts_mapper;
83
84 FreeRegionList _free_list;
85
86 // Each bit in this bitmap indicates that the corresponding region is available
87 // for allocation.
88 CHeapBitMap _available_map;
89
90 // The number of regions committed in the heap.
91 uint _num_committed;
92
93 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
94 uint _allocated_heapregions_length;
95
96 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
97 HeapWord* heap_end() const {return _regions.end_address_mapped(); }
98
99 void make_regions_available(uint index, uint num_regions = 1, WorkGang* pretouch_gang = NULL);
100
101 // Pass down commit calls to the VirtualSpace.
102 void commit_regions(uint index, size_t num_regions = 1, WorkGang* pretouch_gang = NULL);
103 void uncommit_regions(uint index, size_t num_regions = 1);
104
105 // Notify other data structures about change in the heap layout.
106 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
107
108 // Find a contiguous set of empty or uncommitted regions of length num and return
109 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.
110 // If only_empty is true, only empty regions are considered.
111 // Searches from bottom to top of the heap, doing a first-fit.
112 uint find_contiguous(size_t num, bool only_empty);
113 // Finds the next sequence of unavailable regions starting from start_idx. Returns the
114 // length of the sequence found. If this result is zero, no such sequence could be found,
115 // otherwise res_idx indicates the start index of these regions.
116 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
117 // Finds the next sequence of empty regions starting from start_idx, going backwards in
118 // the heap. Returns the length of the sequence found. If this value is zero, no
119 // sequence could be found, otherwise res_idx contains the start index of this range.
120 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
121 // Allocate a new HeapRegion for the given index.
122 HeapRegion* new_heap_region(uint hrm_index);
123 #ifdef ASSERT
124 public:
125 bool is_free(HeapRegion* hr) const;
126 #endif
127 // Returns whether the given region is available for allocation.
128 bool is_available(uint region) const;
129
130 public:
131 // Empty constructor, we'll initialize it with the initialize() method.
132 HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0),
133 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),
134 _allocated_heapregions_length(0), _available_map(),
135 _free_list("Free list", new MasterFreeRegionListMtSafeChecker())
136 { }
137
138 void initialize(G1RegionToSpaceMapper* heap_storage,
139 G1RegionToSpaceMapper* prev_bitmap,
140 G1RegionToSpaceMapper* next_bitmap,
141 G1RegionToSpaceMapper* bot,
142 G1RegionToSpaceMapper* cardtable,
143 G1RegionToSpaceMapper* card_counts);
144
145 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
146 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
147 // the heap from the lowest address, this region (and its associated data
148 // structures) are available and we do not need to check further.
149 HeapRegion* get_dummy_region() { return new_heap_region(0); }
150
151 // Return the HeapRegion at the given index. Assume that the index
152 // is valid.
153 inline HeapRegion* at(uint index) const;
154
155 // Return the next region (by index) that is part of the same
156 // humongous object that hr is part of.
157 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
158
159 // If addr is within the committed space return its corresponding
160 // HeapRegion, otherwise return NULL.
161 inline HeapRegion* addr_to_region(HeapWord* addr) const;
162
163 // Insert the given region into the free region list.
164 inline void insert_into_free_list(HeapRegion* hr);
165
166 // Insert the given region list into the global free region list.
167 void insert_list_into_free_list(FreeRegionList* list) {
168 _free_list.add_ordered(list);
169 }
170
171 HeapRegion* allocate_free_region(bool is_old) {
172 HeapRegion* hr = _free_list.remove_region(is_old);
173
174 if (hr != NULL) {
175 assert(hr->next() == NULL, "Single region should not have next");
176 assert(is_available(hr->hrm_index()), "Must be committed");
177 }
178 return hr;
179 }
180
181 inline void allocate_free_regions_starting_at(uint first, uint num_regions);
182
183 // Remove all regions from the free list.
184 void remove_all_free_regions() {
185 _free_list.remove_all();
186 }
187
188 // Return the number of committed free regions in the heap.
189 uint num_free_regions() const {
190 return _free_list.length();
191 }
192
193 size_t total_capacity_bytes() const {
194 return num_free_regions() * HeapRegion::GrainBytes;
195 }
196
197 // Return the number of available (uncommitted) regions.
198 uint available() const { return max_length() - length(); }
199
200 // Return the number of regions that have been committed in the heap.
201 uint length() const { return _num_committed; }
202
203 // Return the maximum number of regions in the heap.
204 uint max_length() const { return (uint)_regions.length(); }
205
206 MemoryUsage get_auxiliary_data_memory_usage() const;
207
208 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
209
210 // Expand the sequence to reflect that the heap has grown. Either create new
211 // HeapRegions, or re-use existing ones. Returns the number of regions the
212 // sequence was expanded by. If a HeapRegion allocation fails, the resulting
213 // number of regions might be smaller than what's desired.
214 uint expand_by(uint num_regions, WorkGang* pretouch_workers);
215
216 // Makes sure that the regions from start to start+num_regions-1 are available
217 // for allocation. Returns the number of regions that were committed to achieve
218 // this.
219 uint expand_at(uint start, uint num_regions, WorkGang* pretouch_workers);
220
221 // Find a contiguous set of empty regions of length num. Returns the start index of
222 // that set, or G1_NO_HRM_INDEX.
223 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
224 // Find a contiguous set of empty or unavailable regions of length num. Returns the
225 // start index of that set, or G1_NO_HRM_INDEX.
226 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
227
228 HeapRegion* next_region_in_heap(const HeapRegion* r) const;
229
230 // Find the highest free or uncommitted region in the reserved heap,
231 // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.
232 // Set the 'expanded' boolean true if a new region was committed.
233 uint find_highest_free(bool* expanded);
234
235 // Allocate the regions that contain the address range specified, committing the
236 // regions if necessary. Return false if any of the regions is already committed
237 // and not free, and return the number of regions newly committed in commit_count.
238 bool allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers);
239
240 // Apply blk->doHeapRegion() on all committed regions in address order,
241 // terminating the iteration early if doHeapRegion() returns true.
242 void iterate(HeapRegionClosure* blk) const;
243
244 void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const;
245
246 // Uncommit up to num_regions_to_remove regions that are completely free.
247 // Return the actual number of uncommitted regions.
248 uint shrink_by(uint num_regions_to_remove);
249
250 // Uncommit a number of regions starting at the specified index, which must be available,
251 // empty, and free.
252 void shrink_at(uint index, size_t num_regions);
253
254 void verify();
255
256 // Do some sanity checking.
257 void verify_optional() PRODUCT_RETURN;
258 };
259
260 // The HeapRegionClaimer is used during parallel iteration over heap regions,
261 // allowing workers to claim heap regions, gaining exclusive rights to these regions.
262 class HeapRegionClaimer : public StackObj {
263 uint _n_workers;
264 uint _n_regions;
265 volatile uint* _claims;
266
267 static const uint Unclaimed = 0;
268 static const uint Claimed = 1;
269
270 public:
271 HeapRegionClaimer(uint n_workers);
272 ~HeapRegionClaimer();
273
274 inline uint n_regions() const {
275 return _n_regions;
276 }
277
278 // Calculate the starting region for given worker so
279 // that they do not all start from the same region.
280 uint start_region_for_worker(uint worker_id) const;
281
282 // Check if region has been claimed with this HRClaimer.
283 bool is_region_claimed(uint region_index) const;
284
285 // Claim the given region, returns true if successfully claimed.
286 bool claim_region(uint region_index);
287 };
288
289 // Subclass of AbstractGangTask that uses a HeapRegionClaimer to parallelize work on a region basis
290 class G1ParallelizeByRegionsTask: public AbstractGangTask {
291 HeapRegionClaimer _hrclaimer;
292
293 public:
294 G1ParallelizeByRegionsTask(const char* name, uint num_workers) :
295 AbstractGangTask(name),
296 _hrclaimer(num_workers) {}
297
298 protected:
299 void all_heap_regions_work(HeapRegionClosure* cl,
300 uint worker_id,
301 bool concurrent = false);
302 };
303 #endif // SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP