1 /* 2 * Copyright (c) 1997, 2013, 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 "memory/heap.hpp" 27 #include "oops/oop.inline.hpp" 28 #include "runtime/os.hpp" 29 #include "services/memTracker.hpp" 30 31 size_t CodeHeap::header_size() { 32 return sizeof(HeapBlock); 33 } 34 35 36 // Implementation of Heap 37 38 CodeHeap::CodeHeap(const char* name, const int code_blob_type) 39 : _code_blob_type(code_blob_type) { 40 _name = name; 41 _number_of_committed_segments = 0; 42 _number_of_reserved_segments = 0; 43 _segment_size = 0; 44 _log2_segment_size = 0; 45 _next_segment = 0; 46 _freelist = NULL; 47 _freelist_segments = 0; 48 _max_allocated_capacity = 0; 49 _was_full = false; 50 } 51 52 53 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) { 54 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 55 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 56 // setup _segmap pointers for faster indexing 57 address p = (address)_segmap.low() + beg; 58 address q = (address)_segmap.low() + end; 59 // initialize interval 60 while (p < q) *p++ = 0xFF; 61 } 62 63 64 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) { 65 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 66 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 67 // setup _segmap pointers for faster indexing 68 address p = (address)_segmap.low() + beg; 69 address q = (address)_segmap.low() + end; 70 // initialize interval 71 int i = 0; 72 while (p < q) { 73 *p++ = i++; 74 if (i == 0xFF) i = 1; 75 } 76 } 77 78 79 static size_t align_to_page_size(size_t size) { 80 const size_t alignment = (size_t)os::vm_page_size(); 81 assert(is_power_of_2(alignment), "no kidding ???"); 82 return (size + alignment - 1) & ~(alignment - 1); 83 } 84 85 86 void CodeHeap::on_code_mapping(char* base, size_t size) { 87 #ifdef LINUX 88 extern void linux_wrap_code(char* base, size_t size); 89 linux_wrap_code(base, size); 90 #endif 91 } 92 93 94 bool CodeHeap::reserve(ReservedSpace rs, size_t committed_size, size_t segment_size) { 95 assert(segment_size >= sizeof(FreeBlock), "segment size is too small"); 96 assert(is_power_of_2(segment_size), "segment_size must be a power of 2"); 97 98 _segment_size = segment_size; 99 _log2_segment_size = exact_log2(segment_size); 100 101 // Reserve and initialize space for _memory. 102 const size_t page_size = os::can_execute_large_page_memory() ? 103 os::page_size_for_region(committed_size, rs.size(), 8) : 104 os::vm_page_size(); 105 const size_t granularity = os::vm_allocation_granularity(); 106 const size_t c_size = align_size_up(committed_size, page_size); 107 108 os::trace_page_sizes(_name, committed_size, rs.size(), page_size, 109 rs.base(), rs.size()); 110 if (!_memory.initialize(rs, c_size)) { 111 return false; 112 } 113 114 on_code_mapping(_memory.low(), _memory.committed_size()); 115 _number_of_committed_segments = size_to_segments(_memory.committed_size()); 116 _number_of_reserved_segments = size_to_segments(_memory.reserved_size()); 117 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 118 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity); 119 const size_t reserved_segments_size = align_size_up(_number_of_reserved_segments, reserved_segments_alignment); 120 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments); 121 122 // reserve space for _segmap 123 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) { 124 return false; 125 } 126 127 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode); 128 129 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map"); 130 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map"); 131 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking"); 132 133 // initialize remaining instance variables 134 clear(); 135 return true; 136 } 137 138 139 void CodeHeap::release() { 140 Unimplemented(); 141 } 142 143 144 bool CodeHeap::expand_by(size_t size) { 145 // expand _memory space 146 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size(); 147 if (dm > 0) { 148 char* base = _memory.low() + _memory.committed_size(); 149 if (!_memory.expand_by(dm)) return false; 150 on_code_mapping(base, dm); 151 size_t i = _number_of_committed_segments; 152 _number_of_committed_segments = size_to_segments(_memory.committed_size()); 153 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change"); 154 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 155 // expand _segmap space 156 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size(); 157 if (ds > 0) { 158 if (!_segmap.expand_by(ds)) return false; 159 } 160 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking"); 161 // initialize additional segmap entries 162 mark_segmap_as_free(i, _number_of_committed_segments); 163 } 164 return true; 165 } 166 167 168 void CodeHeap::shrink_by(size_t size) { 169 Unimplemented(); 170 } 171 172 173 void CodeHeap::clear() { 174 _next_segment = 0; 175 mark_segmap_as_free(0, _number_of_committed_segments); 176 } 177 178 179 void* CodeHeap::allocate(size_t instance_size, bool is_critical) { 180 size_t number_of_segments = size_to_segments(instance_size + sizeof(HeapBlock)); 181 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList"); 182 183 // First check if we can satify request from freelist 184 debug_only(verify()); 185 HeapBlock* block = search_freelist(number_of_segments, is_critical); 186 debug_only(if (VerifyCodeCacheOften) verify()); 187 if (block != NULL) { 188 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check"); 189 assert(!block->free(), "must be marked free"); 190 #ifdef ASSERT 191 memset((void *)block->allocated_space(), badCodeHeapNewVal, instance_size); 192 #endif 193 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity()); 194 return block->allocated_space(); 195 } 196 197 // Ensure minimum size for allocation to the heap. 198 if (number_of_segments < CodeCacheMinBlockLength) { 199 number_of_segments = CodeCacheMinBlockLength; 200 } 201 202 if (!is_critical) { 203 // Make sure the allocation fits in the unallocated heap without using 204 // the CodeCacheMimimumFreeSpace that is reserved for critical allocations. 205 if (segments_to_size(number_of_segments) > (heap_unallocated_capacity() - CodeCacheMinimumFreeSpace)) { 206 // Fail allocation 207 return NULL; 208 } 209 } 210 211 if (_next_segment + number_of_segments <= _number_of_committed_segments) { 212 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments); 213 HeapBlock* b = block_at(_next_segment); 214 b->initialize(number_of_segments); 215 _next_segment += number_of_segments; 216 #ifdef ASSERT 217 memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size); 218 #endif 219 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity()); 220 return b->allocated_space(); 221 } else { 222 return NULL; 223 } 224 } 225 226 227 void CodeHeap::deallocate(void* p) { 228 assert(p == find_start(p), "illegal deallocation"); 229 // Find start of HeapBlock 230 HeapBlock* b = (((HeapBlock *)p) - 1); 231 assert(b->allocated_space() == p, "sanity check"); 232 #ifdef ASSERT 233 memset((void *)b->allocated_space(), 234 badCodeHeapFreeVal, 235 segments_to_size(b->length()) - sizeof(HeapBlock)); 236 #endif 237 add_to_freelist(b); 238 239 debug_only(if (VerifyCodeCacheOften) verify()); 240 } 241 242 243 void* CodeHeap::find_start(void* p) const { 244 if (!contains(p)) { 245 return NULL; 246 } 247 size_t i = segment_for(p); 248 address b = (address)_segmap.low(); 249 if (b[i] == 0xFF) { 250 return NULL; 251 } 252 while (b[i] > 0) i -= (int)b[i]; 253 HeapBlock* h = block_at(i); 254 if (h->free()) { 255 return NULL; 256 } 257 return h->allocated_space(); 258 } 259 260 261 size_t CodeHeap::alignment_unit() const { 262 // this will be a power of two 263 return _segment_size; 264 } 265 266 267 size_t CodeHeap::alignment_offset() const { 268 // The lowest address in any allocated block will be 269 // equal to alignment_offset (mod alignment_unit). 270 return sizeof(HeapBlock) & (_segment_size - 1); 271 } 272 273 // Finds the next free heapblock. If the current one is free, that it returned 274 void* CodeHeap::next_free(HeapBlock *b) const { 275 // Since free blocks are merged, there is max. on free block 276 // between two used ones 277 if (b != NULL && b->free()) b = next_block(b); 278 assert(b == NULL || !b->free(), "must be in use or at end of heap"); 279 return (b == NULL) ? NULL : b->allocated_space(); 280 } 281 282 // Returns the first used HeapBlock 283 HeapBlock* CodeHeap::first_block() const { 284 if (_next_segment > 0) 285 return block_at(0); 286 return NULL; 287 } 288 289 HeapBlock *CodeHeap::block_start(void *q) const { 290 HeapBlock* b = (HeapBlock*)find_start(q); 291 if (b == NULL) return NULL; 292 return b - 1; 293 } 294 295 // Returns the next Heap block an offset into one 296 HeapBlock* CodeHeap::next_block(HeapBlock *b) const { 297 if (b == NULL) return NULL; 298 size_t i = segment_for(b) + b->length(); 299 if (i < _next_segment) 300 return block_at(i); 301 return NULL; 302 } 303 304 305 // Returns current capacity 306 size_t CodeHeap::capacity() const { 307 return _memory.committed_size(); 308 } 309 310 size_t CodeHeap::max_capacity() const { 311 return _memory.reserved_size(); 312 } 313 314 size_t CodeHeap::allocated_capacity() const { 315 // size of used heap - size on freelist 316 return segments_to_size(_next_segment - _freelist_segments); 317 } 318 319 // Returns size of the unallocated heap block 320 size_t CodeHeap::heap_unallocated_capacity() const { 321 // Total number of segments - number currently used 322 return segments_to_size(_number_of_reserved_segments - _next_segment); 323 } 324 325 // Free list management 326 327 FreeBlock *CodeHeap::following_block(FreeBlock *b) { 328 return (FreeBlock*)(((address)b) + _segment_size * b->length()); 329 } 330 331 // Inserts block b after a 332 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) { 333 assert(a != NULL && b != NULL, "must be real pointers"); 334 335 // Link b into the list after a 336 b->set_link(a->link()); 337 a->set_link(b); 338 339 // See if we can merge blocks 340 merge_right(b); // Try to make b bigger 341 merge_right(a); // Try to make a include b 342 } 343 344 // Try to merge this block with the following block 345 void CodeHeap::merge_right(FreeBlock *a) { 346 assert(a->free(), "must be a free block"); 347 if (following_block(a) == a->link()) { 348 assert(a->link() != NULL && a->link()->free(), "must be free too"); 349 // Update block a to include the following block 350 a->set_length(a->length() + a->link()->length()); 351 a->set_link(a->link()->link()); 352 // Update find_start map 353 size_t beg = segment_for(a); 354 mark_segmap_as_used(beg, beg + a->length()); 355 } 356 } 357 358 void CodeHeap::add_to_freelist(HeapBlock *a) { 359 FreeBlock* b = (FreeBlock*)a; 360 assert(b != _freelist, "cannot be removed twice"); 361 362 // Mark as free and update free space count 363 _freelist_segments += b->length(); 364 b->set_free(); 365 366 // First element in list? 367 if (_freelist == NULL) { 368 _freelist = b; 369 b->set_link(NULL); 370 return; 371 } 372 373 // Scan for right place to put into list. List 374 // is sorted by increasing addresseses 375 FreeBlock* prev = NULL; 376 FreeBlock* cur = _freelist; 377 while(cur != NULL && cur < b) { 378 assert(prev == NULL || prev < cur, "must be ordered"); 379 prev = cur; 380 cur = cur->link(); 381 } 382 383 assert( (prev == NULL && b < _freelist) || 384 (prev < b && (cur == NULL || b < cur)), "list must be ordered"); 385 386 if (prev == NULL) { 387 // Insert first in list 388 b->set_link(_freelist); 389 _freelist = b; 390 merge_right(_freelist); 391 } else { 392 insert_after(prev, b); 393 } 394 } 395 396 // Search freelist for an entry on the list with the best fit 397 // Return NULL if no one was found 398 FreeBlock* CodeHeap::search_freelist(size_t length, bool is_critical) { 399 FreeBlock *best_block = NULL; 400 FreeBlock *best_prev = NULL; 401 size_t best_length = 0; 402 403 // Search for smallest block which is bigger than length 404 FreeBlock *prev = NULL; 405 FreeBlock *cur = _freelist; 406 while(cur != NULL) { 407 size_t l = cur->length(); 408 if (l >= length && (best_block == NULL || best_length > l)) { 409 410 // Non critical allocations are not allowed to use the last part of the code heap. 411 if (!is_critical) { 412 // Make sure the end of the allocation doesn't cross into the last part of the code heap 413 if (((size_t)cur + length) > ((size_t)high_boundary() - CodeCacheMinimumFreeSpace)) { 414 // the freelist is sorted by address - if one fails, all consecutive will also fail. 415 break; 416 } 417 } 418 419 // Remember best block, its previous element, and its length 420 best_block = cur; 421 best_prev = prev; 422 best_length = best_block->length(); 423 } 424 425 // Next element in list 426 prev = cur; 427 cur = cur->link(); 428 } 429 430 if (best_block == NULL) { 431 // None found 432 return NULL; 433 } 434 435 assert((best_prev == NULL && _freelist == best_block ) || 436 (best_prev != NULL && best_prev->link() == best_block), "sanity check"); 437 438 // Exact (or at least good enough) fit. Remove from list. 439 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength. 440 if (best_length < length + CodeCacheMinBlockLength) { 441 length = best_length; 442 if (best_prev == NULL) { 443 assert(_freelist == best_block, "sanity check"); 444 _freelist = _freelist->link(); 445 } else { 446 // Unmap element 447 best_prev->set_link(best_block->link()); 448 } 449 } else { 450 // Truncate block and return a pointer to the following block 451 best_block->set_length(best_length - length); 452 best_block = following_block(best_block); 453 // Set used bit and length on new block 454 size_t beg = segment_for(best_block); 455 mark_segmap_as_used(beg, beg + length); 456 best_block->set_length(length); 457 } 458 459 best_block->set_used(); 460 _freelist_segments -= length; 461 return best_block; 462 } 463 464 //---------------------------------------------------------------------------- 465 // Non-product code 466 467 #ifndef PRODUCT 468 469 void CodeHeap::print() { 470 tty->print_cr("The Heap"); 471 } 472 473 #endif 474 475 void CodeHeap::verify() { 476 // Count the number of blocks on the freelist, and the amount of space 477 // represented. 478 int count = 0; 479 size_t len = 0; 480 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) { 481 len += b->length(); 482 count++; 483 } 484 485 // Verify that freelist contains the right amount of free space 486 // guarantee(len == _freelist_segments, "wrong freelist"); 487 488 // Verify that the number of free blocks is not out of hand. 489 static int free_block_threshold = 10000; 490 if (count > free_block_threshold) { 491 warning("CodeHeap: # of free blocks > %d", free_block_threshold); 492 // Double the warning limit 493 free_block_threshold *= 2; 494 } 495 496 // Verify that the freelist contains the same number of free blocks that is 497 // found on the full list. 498 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) { 499 if (h->free()) count--; 500 } 501 // guarantee(count == 0, "missing free blocks"); 502 }