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() { 39 _number_of_committed_segments = 0; 40 _number_of_reserved_segments = 0; 41 _segment_size = 0; 42 _log2_segment_size = 0; 43 _next_segment = 0; 44 _freelist = NULL; 45 _freelist_segments = 0; 46 } 47 48 49 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) { 50 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 51 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 52 // setup _segmap pointers for faster indexing 53 address p = (address)_segmap.low() + beg; 54 address q = (address)_segmap.low() + end; 55 // initialize interval 56 while (p < q) *p++ = 0xFF; 57 } 58 59 60 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) { 61 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 62 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 63 // setup _segmap pointers for faster indexing 64 address p = (address)_segmap.low() + beg; 65 address q = (address)_segmap.low() + end; 66 // initialize interval 67 int i = 0; 68 while (p < q) { 69 *p++ = i++; 70 if (i == 0xFF) i = 1; 71 } 72 } 73 74 75 static size_t align_to_page_size(size_t size) { 76 const size_t alignment = (size_t)os::vm_page_size(); 77 assert(is_power_of_2(alignment), "no kidding ???"); 78 return (size + alignment - 1) & ~(alignment - 1); 79 } 80 81 82 void CodeHeap::on_code_mapping(char* base, size_t size) { 83 #ifdef LINUX 84 extern void linux_wrap_code(char* base, size_t size); 85 linux_wrap_code(base, size); 86 #endif 87 } 88 89 90 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size, 91 size_t segment_size) { 92 assert(reserved_size >= committed_size, "reserved < committed"); 93 assert(segment_size >= sizeof(FreeBlock), "segment size is too small"); 94 assert(is_power_of_2(segment_size), "segment_size must be a power of 2"); 95 96 _segment_size = segment_size; 97 _log2_segment_size = exact_log2(segment_size); 98 99 // Reserve and initialize space for _memory. 100 size_t page_size = os::vm_page_size(); 101 if (os::can_execute_large_page_memory()) { 102 page_size = os::page_size_for_region_unaligned(reserved_size, 8); 103 } 104 105 const size_t granularity = os::vm_allocation_granularity(); 106 const size_t r_align = MAX2(page_size, granularity); 107 const size_t r_size = align_size_up(reserved_size, r_align); 108 const size_t c_size = align_size_up(committed_size, page_size); 109 110 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 : 111 MAX2(page_size, granularity); 112 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0); 113 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size, 114 rs.base(), rs.size()); 115 if (!_memory.initialize(rs, c_size)) { 116 return false; 117 } 118 119 on_code_mapping(_memory.low(), _memory.committed_size()); 120 _number_of_committed_segments = size_to_segments(_memory.committed_size()); 121 _number_of_reserved_segments = size_to_segments(_memory.reserved_size()); 122 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 123 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity); 124 const size_t reserved_segments_size = align_size_up(_number_of_reserved_segments, reserved_segments_alignment); 125 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments); 126 127 // reserve space for _segmap 128 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) { 129 return false; 130 } 131 132 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode); 133 134 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map"); 135 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map"); 136 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking"); 137 138 // initialize remaining instance variables 139 clear(); 140 return true; 141 } 142 143 144 void CodeHeap::release() { 145 Unimplemented(); 146 } 147 148 149 bool CodeHeap::expand_by(size_t size) { 150 // expand _memory space 151 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size(); 152 if (dm > 0) { 153 char* base = _memory.low() + _memory.committed_size(); 154 if (!_memory.expand_by(dm)) return false; 155 on_code_mapping(base, dm); 156 size_t i = _number_of_committed_segments; 157 _number_of_committed_segments = size_to_segments(_memory.committed_size()); 158 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change"); 159 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 160 // expand _segmap space 161 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size(); 162 if (ds > 0) { 163 if (!_segmap.expand_by(ds)) return false; 164 } 165 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking"); 166 // initialize additional segmap entries 167 mark_segmap_as_free(i, _number_of_committed_segments); 168 } 169 return true; 170 } 171 172 173 void CodeHeap::shrink_by(size_t size) { 174 Unimplemented(); 175 } 176 177 178 void CodeHeap::clear() { 179 _next_segment = 0; 180 mark_segmap_as_free(0, _number_of_committed_segments); 181 } 182 183 184 void* CodeHeap::allocate(size_t instance_size, bool is_critical) { 185 size_t number_of_segments = size_to_segments(instance_size + sizeof(HeapBlock)); 186 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList"); 187 188 // First check if we can satify request from freelist 189 debug_only(verify()); 190 HeapBlock* block = search_freelist(number_of_segments, is_critical); 191 debug_only(if (VerifyCodeCacheOften) verify()); 192 if (block != NULL) { 193 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check"); 194 assert(!block->free(), "must be marked free"); 195 #ifdef ASSERT 196 memset((void *)block->allocated_space(), badCodeHeapNewVal, instance_size); 197 #endif 198 return block->allocated_space(); 199 } 200 201 // Ensure minimum size for allocation to the heap. 202 if (number_of_segments < CodeCacheMinBlockLength) { 203 number_of_segments = CodeCacheMinBlockLength; 204 } 205 206 if (!is_critical) { 207 // Make sure the allocation fits in the unallocated heap without using 208 // the CodeCacheMimimumFreeSpace that is reserved for critical allocations. 209 if (segments_to_size(number_of_segments) > (heap_unallocated_capacity() - CodeCacheMinimumFreeSpace)) { 210 // Fail allocation 211 return NULL; 212 } 213 } 214 215 if (_next_segment + number_of_segments <= _number_of_committed_segments) { 216 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments); 217 HeapBlock* b = block_at(_next_segment); 218 b->initialize(number_of_segments); 219 _next_segment += number_of_segments; 220 #ifdef ASSERT 221 memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size); 222 #endif 223 return b->allocated_space(); 224 } else { 225 return NULL; 226 } 227 } 228 229 230 void CodeHeap::deallocate(void* p) { 231 assert(p == find_start(p), "illegal deallocation"); 232 // Find start of HeapBlock 233 HeapBlock* b = (((HeapBlock *)p) - 1); 234 assert(b->allocated_space() == p, "sanity check"); 235 #ifdef ASSERT 236 memset((void *)b->allocated_space(), 237 badCodeHeapFreeVal, 238 segments_to_size(b->length()) - sizeof(HeapBlock)); 239 #endif 240 add_to_freelist(b); 241 242 debug_only(if (VerifyCodeCacheOften) verify()); 243 } 244 245 246 void* CodeHeap::find_start(void* p) const { 247 if (!contains(p)) { 248 return NULL; 249 } 250 size_t i = segment_for(p); 251 address b = (address)_segmap.low(); 252 if (b[i] == 0xFF) { 253 return NULL; 254 } 255 while (b[i] > 0) i -= (int)b[i]; 256 HeapBlock* h = block_at(i); 257 if (h->free()) { 258 return NULL; 259 } 260 return h->allocated_space(); 261 } 262 263 264 size_t CodeHeap::alignment_unit() const { 265 // this will be a power of two 266 return _segment_size; 267 } 268 269 270 size_t CodeHeap::alignment_offset() const { 271 // The lowest address in any allocated block will be 272 // equal to alignment_offset (mod alignment_unit). 273 return sizeof(HeapBlock) & (_segment_size - 1); 274 } 275 276 // Finds the next free heapblock. If the current one is free, that it returned 277 void* CodeHeap::next_free(HeapBlock *b) const { 278 // Since free blocks are merged, there is max. on free block 279 // between two used ones 280 if (b != NULL && b->free()) b = next_block(b); 281 assert(b == NULL || !b->free(), "must be in use or at end of heap"); 282 return (b == NULL) ? NULL : b->allocated_space(); 283 } 284 285 // Returns the first used HeapBlock 286 HeapBlock* CodeHeap::first_block() const { 287 if (_next_segment > 0) 288 return block_at(0); 289 return NULL; 290 } 291 292 HeapBlock *CodeHeap::block_start(void *q) const { 293 HeapBlock* b = (HeapBlock*)find_start(q); 294 if (b == NULL) return NULL; 295 return b - 1; 296 } 297 298 // Returns the next Heap block an offset into one 299 HeapBlock* CodeHeap::next_block(HeapBlock *b) const { 300 if (b == NULL) return NULL; 301 size_t i = segment_for(b) + b->length(); 302 if (i < _next_segment) 303 return block_at(i); 304 return NULL; 305 } 306 307 308 // Returns current capacity 309 size_t CodeHeap::capacity() const { 310 return _memory.committed_size(); 311 } 312 313 size_t CodeHeap::max_capacity() const { 314 return _memory.reserved_size(); 315 } 316 317 size_t CodeHeap::allocated_capacity() const { 318 // size of used heap - size on freelist 319 return segments_to_size(_next_segment - _freelist_segments); 320 } 321 322 // Returns size of the unallocated heap block 323 size_t CodeHeap::heap_unallocated_capacity() const { 324 // Total number of segments - number currently used 325 return segments_to_size(_number_of_reserved_segments - _next_segment); 326 } 327 328 // Free list management 329 330 FreeBlock *CodeHeap::following_block(FreeBlock *b) { 331 return (FreeBlock*)(((address)b) + _segment_size * b->length()); 332 } 333 334 // Inserts block b after a 335 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) { 336 assert(a != NULL && b != NULL, "must be real pointers"); 337 338 // Link b into the list after a 339 b->set_link(a->link()); 340 a->set_link(b); 341 342 // See if we can merge blocks 343 merge_right(b); // Try to make b bigger 344 merge_right(a); // Try to make a include b 345 } 346 347 // Try to merge this block with the following block 348 void CodeHeap::merge_right(FreeBlock *a) { 349 assert(a->free(), "must be a free block"); 350 if (following_block(a) == a->link()) { 351 assert(a->link() != NULL && a->link()->free(), "must be free too"); 352 // Update block a to include the following block 353 a->set_length(a->length() + a->link()->length()); 354 a->set_link(a->link()->link()); 355 // Update find_start map 356 size_t beg = segment_for(a); 357 mark_segmap_as_used(beg, beg + a->length()); 358 } 359 } 360 361 void CodeHeap::add_to_freelist(HeapBlock *a) { 362 FreeBlock* b = (FreeBlock*)a; 363 assert(b != _freelist, "cannot be removed twice"); 364 365 // Mark as free and update free space count 366 _freelist_segments += b->length(); 367 b->set_free(); 368 369 // First element in list? 370 if (_freelist == NULL) { 371 _freelist = b; 372 b->set_link(NULL); 373 return; 374 } 375 376 // Scan for right place to put into list. List 377 // is sorted by increasing addresseses 378 FreeBlock* prev = NULL; 379 FreeBlock* cur = _freelist; 380 while(cur != NULL && cur < b) { 381 assert(prev == NULL || prev < cur, "must be ordered"); 382 prev = cur; 383 cur = cur->link(); 384 } 385 386 assert( (prev == NULL && b < _freelist) || 387 (prev < b && (cur == NULL || b < cur)), "list must be ordered"); 388 389 if (prev == NULL) { 390 // Insert first in list 391 b->set_link(_freelist); 392 _freelist = b; 393 merge_right(_freelist); 394 } else { 395 insert_after(prev, b); 396 } 397 } 398 399 // Search freelist for an entry on the list with the best fit 400 // Return NULL if no one was found 401 FreeBlock* CodeHeap::search_freelist(size_t length, bool is_critical) { 402 FreeBlock *best_block = NULL; 403 FreeBlock *best_prev = NULL; 404 size_t best_length = 0; 405 406 // Search for smallest block which is bigger than length 407 FreeBlock *prev = NULL; 408 FreeBlock *cur = _freelist; 409 while(cur != NULL) { 410 size_t l = cur->length(); 411 if (l >= length && (best_block == NULL || best_length > l)) { 412 413 // Non critical allocations are not allowed to use the last part of the code heap. 414 if (!is_critical) { 415 // Make sure the end of the allocation doesn't cross into the last part of the code heap 416 if (((size_t)cur + length) > ((size_t)high_boundary() - CodeCacheMinimumFreeSpace)) { 417 // the freelist is sorted by address - if one fails, all consecutive will also fail. 418 break; 419 } 420 } 421 422 // Remember best block, its previous element, and its length 423 best_block = cur; 424 best_prev = prev; 425 best_length = best_block->length(); 426 } 427 428 // Next element in list 429 prev = cur; 430 cur = cur->link(); 431 } 432 433 if (best_block == NULL) { 434 // None found 435 return NULL; 436 } 437 438 assert((best_prev == NULL && _freelist == best_block ) || 439 (best_prev != NULL && best_prev->link() == best_block), "sanity check"); 440 441 // Exact (or at least good enough) fit. Remove from list. 442 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength. 443 if (best_length < length + CodeCacheMinBlockLength) { 444 length = best_length; 445 if (best_prev == NULL) { 446 assert(_freelist == best_block, "sanity check"); 447 _freelist = _freelist->link(); 448 } else { 449 // Unmap element 450 best_prev->set_link(best_block->link()); 451 } 452 } else { 453 // Truncate block and return a pointer to the following block 454 best_block->set_length(best_length - length); 455 best_block = following_block(best_block); 456 // Set used bit and length on new block 457 size_t beg = segment_for(best_block); 458 mark_segmap_as_used(beg, beg + length); 459 best_block->set_length(length); 460 } 461 462 best_block->set_used(); 463 _freelist_segments -= length; 464 return best_block; 465 } 466 467 //---------------------------------------------------------------------------- 468 // Non-product code 469 470 #ifndef PRODUCT 471 472 void CodeHeap::print() { 473 tty->print_cr("The Heap"); 474 } 475 476 #endif 477 478 void CodeHeap::verify() { 479 // Count the number of blocks on the freelist, and the amount of space 480 // represented. 481 int count = 0; 482 size_t len = 0; 483 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) { 484 len += b->length(); 485 count++; 486 } 487 488 // Verify that freelist contains the right amount of free space 489 // guarantee(len == _freelist_segments, "wrong freelist"); 490 491 // Verify that the number of free blocks is not out of hand. 492 static int free_block_threshold = 10000; 493 if (count > free_block_threshold) { 494 warning("CodeHeap: # of free blocks > %d", free_block_threshold); 495 // Double the warning limit 496 free_block_threshold *= 2; 497 } 498 499 // Verify that the freelist contains the same number of free blocks that is 500 // found on the full list. 501 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) { 502 if (h->free()) count--; 503 } 504 // guarantee(count == 0, "missing free blocks"); 505 }