1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 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/heapRegion.hpp" 27 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 28 #include "gc_implementation/g1/heapRegionSets.hpp" 29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 30 #include "memory/allocation.hpp" 31 32 // Private 33 34 uint HeapRegionSeq::find_contiguous_from(uint from, uint num) { 35 uint len = length(); 36 assert(num > 1, "use this only for sequences of length 2 or greater"); 37 assert(from <= len, 38 err_msg("from: %u should be valid and <= than %u", from, len)); 39 40 uint curr = from; 41 uint first = G1_NULL_HRS_INDEX; 42 uint num_so_far = 0; 43 while (curr < len && num_so_far < num) { 44 if (at(curr)->is_empty()) { 45 if (first == G1_NULL_HRS_INDEX) { 46 first = curr; 47 num_so_far = 1; 48 } else { 49 num_so_far += 1; 50 } 51 } else { 52 first = G1_NULL_HRS_INDEX; 53 num_so_far = 0; 54 } 55 curr += 1; 56 } 57 assert(num_so_far <= num, "post-condition"); 58 if (num_so_far == num) { 59 // we found enough space for the humongous object 60 assert(from <= first && first < len, "post-condition"); 61 assert(first < curr && (curr - first) == num, "post-condition"); 62 for (uint i = first; i < first + num; ++i) { 63 assert(at(i)->is_empty(), "post-condition"); 64 } 65 return first; 66 } else { 67 // we failed to find enough space for the humongous object 68 return G1_NULL_HRS_INDEX; 69 } 70 } 71 72 // Public 73 74 void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* end, 75 uint max_length) { 76 assert((uintptr_t) bottom % HeapRegion::GrainBytes == 0, 77 "bottom should be heap region aligned"); 78 assert((uintptr_t) end % HeapRegion::GrainBytes == 0, 79 "end should be heap region aligned"); 80 81 _length = 0; 82 _heap_bottom = bottom; 83 _heap_end = end; 84 _region_shift = HeapRegion::LogOfHRGrainBytes; 85 _next_search_index = 0; 86 _allocated_length = 0; 87 _max_length = max_length; 88 89 _regions = NEW_C_HEAP_ARRAY(HeapRegion*, max_length, mtGC); 90 memset(_regions, 0, (size_t) max_length * sizeof(HeapRegion*)); 91 _regions_biased = _regions - ((uintx) bottom >> _region_shift); 92 93 assert(&_regions[0] == &_regions_biased[addr_to_index_biased(bottom)], 94 "bottom should be included in the region with index 0"); 95 } 96 97 MemRegion HeapRegionSeq::expand_by(HeapWord* old_end, 98 HeapWord* new_end, 99 FreeRegionList* list) { 100 assert(old_end < new_end, "don't call it otherwise"); 101 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 102 103 HeapWord* next_bottom = old_end; 104 assert(_heap_bottom <= next_bottom, "invariant"); 105 while (next_bottom < new_end) { 106 assert(next_bottom < _heap_end, "invariant"); 107 uint index = length(); 108 109 assert(index < _max_length, "otherwise we cannot expand further"); 110 if (index == 0) { 111 // We have not allocated any regions so far 112 assert(next_bottom == _heap_bottom, "invariant"); 113 } else { 114 // next_bottom should match the end of the last/previous region 115 assert(next_bottom == at(index - 1)->end(), "invariant"); 116 } 117 118 if (index == _allocated_length) { 119 // We have to allocate a new HeapRegion. 120 HeapRegion* new_hr = g1h->new_heap_region(index, next_bottom); 121 if (new_hr == NULL) { 122 // allocation failed, we bail out and return what we have done so far 123 return MemRegion(old_end, next_bottom); 124 } 125 assert(_regions[index] == NULL, "invariant"); 126 _regions[index] = new_hr; 127 increment_length(&_allocated_length); 128 } 129 // Have to increment the length first, otherwise we will get an 130 // assert failure at(index) below. 131 increment_length(&_length); 132 HeapRegion* hr = at(index); 133 list->add_as_tail(hr); 134 135 next_bottom = hr->end(); 136 } 137 assert(next_bottom == new_end, "post-condition"); 138 return MemRegion(old_end, next_bottom); 139 } 140 141 uint HeapRegionSeq::free_suffix() { 142 uint res = 0; 143 uint index = length(); 144 while (index > 0) { 145 index -= 1; 146 if (!at(index)->is_empty()) { 147 break; 148 } 149 res += 1; 150 } 151 return res; 152 } 153 154 uint HeapRegionSeq::find_contiguous(uint num) { 155 assert(num > 1, "use this only for sequences of length 2 or greater"); 156 assert(_next_search_index <= length(), 157 err_msg("_next_search_index: %u should be valid and <= than %u", 158 _next_search_index, length())); 159 160 uint start = _next_search_index; 161 uint res = find_contiguous_from(start, num); 162 if (res == G1_NULL_HRS_INDEX && start > 0) { 163 // Try starting from the beginning. If _next_search_index was 0, 164 // no point in doing this again. 165 res = find_contiguous_from(0, num); 166 } 167 if (res != G1_NULL_HRS_INDEX) { 168 assert(res < length(), err_msg("res: %u should be valid", res)); 169 _next_search_index = res + num; 170 assert(_next_search_index <= length(), 171 err_msg("_next_search_index: %u should be valid and <= than %u", 172 _next_search_index, length())); 173 } 174 return res; 175 } 176 177 void HeapRegionSeq::iterate(HeapRegionClosure* blk) const { 178 iterate_from((HeapRegion*) NULL, blk); 179 } 180 181 void HeapRegionSeq::iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const { 182 uint hr_index = 0; 183 if (hr != NULL) { 184 hr_index = hr->hrs_index(); 185 } 186 187 uint len = length(); 188 for (uint i = hr_index; i < len; i += 1) { 189 bool res = blk->doHeapRegion(at(i)); 190 if (res) { 191 blk->incomplete(); 192 return; 193 } 194 } 195 for (uint i = 0; i < hr_index; i += 1) { 196 bool res = blk->doHeapRegion(at(i)); 197 if (res) { 198 blk->incomplete(); 199 return; 200 } 201 } 202 } 203 204 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes, 205 uint* num_regions_deleted) { 206 // Reset this in case it's currently pointing into the regions that 207 // we just removed. 208 _next_search_index = 0; 209 210 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned"); 211 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned"); 212 assert(length() > 0, "the region sequence should not be empty"); 213 assert(length() <= _allocated_length, "invariant"); 214 assert(_allocated_length > 0, "we should have at least one region committed"); 215 216 // around the loop, i will be the next region to be removed 217 uint i = length() - 1; 218 assert(i > 0, "we should never remove all regions"); 219 // [last_start, end) is the MemRegion that covers the regions we will remove. 220 HeapWord* end = at(i)->end(); 221 HeapWord* last_start = end; 222 *num_regions_deleted = 0; 223 while (shrink_bytes > 0) { 224 HeapRegion* cur = at(i); 225 // We should leave the humongous regions where they are. 226 if (cur->isHumongous()) break; 227 // We should stop shrinking if we come across a non-empty region. 228 if (!cur->is_empty()) break; 229 230 i -= 1; 231 *num_regions_deleted += 1; 232 shrink_bytes -= cur->capacity(); 233 last_start = cur->bottom(); 234 decrement_length(&_length); 235 // We will reclaim the HeapRegion. _allocated_length should be 236 // covering this index. So, even though we removed the region from 237 // the active set by decreasing _length, we still have it 238 // available in the future if we need to re-use it. 239 assert(i > 0, "we should never remove all regions"); 240 assert(length() > 0, "we should never remove all regions"); 241 } 242 return MemRegion(last_start, end); 243 } 244 245 #ifndef PRODUCT 246 void HeapRegionSeq::verify_optional() { 247 guarantee(_length <= _allocated_length, 248 err_msg("invariant: _length: %u _allocated_length: %u", 249 _length, _allocated_length)); 250 guarantee(_allocated_length <= _max_length, 251 err_msg("invariant: _allocated_length: %u _max_length: %u", 252 _allocated_length, _max_length)); 253 guarantee(_next_search_index <= _length, 254 err_msg("invariant: _next_search_index: %u _length: %u", 255 _next_search_index, _length)); 256 257 HeapWord* prev_end = _heap_bottom; 258 for (uint i = 0; i < _allocated_length; i += 1) { 259 HeapRegion* hr = _regions[i]; 260 guarantee(hr != NULL, err_msg("invariant: i: %u", i)); 261 guarantee(hr->bottom() == prev_end, 262 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT, 263 i, HR_FORMAT_PARAMS(hr), prev_end)); 264 guarantee(hr->hrs_index() == i, 265 err_msg("invariant: i: %u hrs_index(): %u", i, hr->hrs_index())); 266 if (i < _length) { 267 // Asserts will fire if i is >= _length 268 HeapWord* addr = hr->bottom(); 269 guarantee(addr_to_region(addr) == hr, "sanity"); 270 guarantee(addr_to_region_unsafe(addr) == hr, "sanity"); 271 } else { 272 guarantee(hr->is_empty(), "sanity"); 273 guarantee(!hr->isHumongous(), "sanity"); 274 // using assert instead of guarantee here since containing_set() 275 // is only available in non-product builds. 276 assert(hr->containing_set() == NULL, "sanity"); 277 } 278 if (hr->startsHumongous()) { 279 prev_end = hr->orig_end(); 280 } else { 281 prev_end = hr->end(); 282 } 283 } 284 for (uint i = _allocated_length; i < _max_length; i += 1) { 285 guarantee(_regions[i] == NULL, err_msg("invariant i: %u", i)); 286 } 287 } 288 #endif // PRODUCT