1 /* 2 * Copyright (c) 1997, 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 "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 _free_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 static size_t align_to_allocation_size(size_t size) { 83 const size_t alignment = (size_t)os::vm_allocation_granularity(); 84 assert(is_power_of_2(alignment), "no kidding ???"); 85 return (size + alignment - 1) & ~(alignment - 1); 86 } 87 88 89 void CodeHeap::on_code_mapping(char* base, size_t size) { 90 #ifdef LINUX 91 extern void linux_wrap_code(char* base, size_t size); 92 linux_wrap_code(base, size); 93 #endif 94 } 95 96 97 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size, 98 size_t segment_size) { 99 assert(reserved_size >= committed_size, "reserved < committed"); 100 assert(segment_size >= sizeof(FreeBlock), "segment size is too small"); 101 assert(is_power_of_2(segment_size), "segment_size must be a power of 2"); 102 103 _segment_size = segment_size; 104 _log2_segment_size = exact_log2(segment_size); 105 106 // Reserve and initialize space for _memory. 107 const size_t page_size = os::can_execute_large_page_memory() ? 108 os::page_size_for_region(committed_size, reserved_size, 8) : 109 os::vm_page_size(); 110 const size_t granularity = os::vm_allocation_granularity(); 111 const size_t r_align = MAX2(page_size, granularity); 112 const size_t r_size = align_size_up(reserved_size, r_align); 113 const size_t c_size = align_size_up(committed_size, page_size); 114 115 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 : 116 MAX2(page_size, granularity); 117 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0); 118 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size, 119 rs.base(), rs.size()); 120 if (!_memory.initialize(rs, c_size)) { 121 return false; 122 } 123 124 on_code_mapping(_memory.low(), _memory.committed_size()); 125 _number_of_committed_segments = number_of_segments(_memory.committed_size()); 126 _number_of_reserved_segments = number_of_segments(_memory.reserved_size()); 127 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 128 129 // reserve space for _segmap 130 if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) { 131 return false; 132 } 133 134 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode); 135 136 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map"); 137 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map"); 138 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking"); 139 140 // initialize remaining instance variables 141 clear(); 142 return true; 143 } 144 145 146 void CodeHeap::release() { 147 Unimplemented(); 148 } 149 150 151 bool CodeHeap::expand_by(size_t size) { 152 // expand _memory space 153 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size(); 154 if (dm > 0) { 155 char* base = _memory.low() + _memory.committed_size(); 156 if (!_memory.expand_by(dm)) return false; 157 on_code_mapping(base, dm); 158 size_t i = _number_of_committed_segments; 159 _number_of_committed_segments = number_of_segments(_memory.committed_size()); 160 assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change"); 161 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 162 // expand _segmap space 163 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size(); 164 if (ds > 0) { 165 if (!_segmap.expand_by(ds)) return false; 166 } 167 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking"); 168 // initialize additional segmap entries 169 mark_segmap_as_free(i, _number_of_committed_segments); 170 } 171 return true; 172 } 173 174 175 void CodeHeap::shrink_by(size_t size) { 176 Unimplemented(); 177 } 178 179 180 void CodeHeap::clear() { 181 _next_segment = 0; 182 mark_segmap_as_free(0, _number_of_committed_segments); 183 } 184 185 186 void* CodeHeap::allocate(size_t size) { 187 size_t length = number_of_segments(size + sizeof(HeapBlock)); 188 assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList"); 189 190 // First check if we can satify request from freelist 191 debug_only(verify()); 192 HeapBlock* block = search_freelist(length); 193 debug_only(if (VerifyCodeCacheOften) verify()); 194 if (block != NULL) { 195 assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check"); 196 assert(!block->free(), "must be marked free"); 197 #ifdef ASSERT 198 memset((void *)block->allocated_space(), badCodeHeapNewVal, size); 199 #endif 200 return block->allocated_space(); 201 } 202 203 if (length < CodeCacheMinBlockLength) { 204 length = CodeCacheMinBlockLength; 205 } 206 if (_next_segment + length <= _number_of_committed_segments) { 207 mark_segmap_as_used(_next_segment, _next_segment + length); 208 HeapBlock* b = block_at(_next_segment); 209 b->initialize(length); 210 _next_segment += length; 211 #ifdef ASSERT 212 memset((void *)b->allocated_space(), badCodeHeapNewVal, size); 213 #endif 214 return b->allocated_space(); 215 } else { 216 return NULL; 217 } 218 } 219 220 221 void CodeHeap::deallocate(void* p) { 222 assert(p == find_start(p), "illegal deallocation"); 223 // Find start of HeapBlock 224 HeapBlock* b = (((HeapBlock *)p) - 1); 225 assert(b->allocated_space() == p, "sanity check"); 226 #ifdef ASSERT 227 memset((void *)b->allocated_space(), 228 badCodeHeapFreeVal, 229 size(b->length()) - sizeof(HeapBlock)); 230 #endif 231 add_to_freelist(b); 232 233 debug_only(if (VerifyCodeCacheOften) verify()); 234 } 235 236 237 void* CodeHeap::find_start(void* p) const { 238 if (!contains(p)) { 239 return NULL; 240 } 241 size_t i = segment_for(p); 242 address b = (address)_segmap.low(); 243 if (b[i] == 0xFF) { 244 return NULL; 245 } 246 while (b[i] > 0) i -= (int)b[i]; 247 HeapBlock* h = block_at(i); 248 if (h->free()) { 249 return NULL; 250 } 251 return h->allocated_space(); 252 } 253 254 255 size_t CodeHeap::alignment_unit() const { 256 // this will be a power of two 257 return _segment_size; 258 } 259 260 261 size_t CodeHeap::alignment_offset() const { 262 // The lowest address in any allocated block will be 263 // equal to alignment_offset (mod alignment_unit). 264 return sizeof(HeapBlock) & (_segment_size - 1); 265 } 266 267 // Finds the next free heapblock. If the current one is free, that it returned 268 void* CodeHeap::next_free(HeapBlock *b) const { 269 // Since free blocks are merged, there is max. on free block 270 // between two used ones 271 if (b != NULL && b->free()) b = next_block(b); 272 assert(b == NULL || !b->free(), "must be in use or at end of heap"); 273 return (b == NULL) ? NULL : b->allocated_space(); 274 } 275 276 // Returns the first used HeapBlock 277 HeapBlock* CodeHeap::first_block() const { 278 if (_next_segment > 0) 279 return block_at(0); 280 return NULL; 281 } 282 283 HeapBlock *CodeHeap::block_start(void *q) const { 284 HeapBlock* b = (HeapBlock*)find_start(q); 285 if (b == NULL) return NULL; 286 return b - 1; 287 } 288 289 // Returns the next Heap block an offset into one 290 HeapBlock* CodeHeap::next_block(HeapBlock *b) const { 291 if (b == NULL) return NULL; 292 size_t i = segment_for(b) + b->length(); 293 if (i < _next_segment) 294 return block_at(i); 295 return NULL; 296 } 297 298 299 // Returns current capacity 300 size_t CodeHeap::capacity() const { 301 return _memory.committed_size(); 302 } 303 304 size_t CodeHeap::max_capacity() const { 305 return _memory.reserved_size(); 306 } 307 308 size_t CodeHeap::allocated_capacity() const { 309 // Start with the committed size in _memory; 310 size_t l = _memory.committed_size(); 311 312 // Subtract the committed, but unused, segments 313 l -= size(_number_of_committed_segments - _next_segment); 314 315 // Subtract the size of the freelist 316 l -= size(_free_segments); 317 318 return l; 319 } 320 321 size_t CodeHeap::largest_free_block() const { 322 // First check unused space excluding free blocks. 323 size_t free_sz = size(_free_segments); 324 size_t unused = max_capacity() - allocated_capacity() - free_sz; 325 if (unused >= free_sz) 326 return unused; 327 328 // Now check largest free block. 329 size_t len = 0; 330 for (FreeBlock* b = _freelist; b != NULL; b = b->link()) { 331 if (b->length() > len) 332 len = b->length(); 333 } 334 return MAX2(unused, size(len)); 335 } 336 337 // Free list management 338 339 FreeBlock *CodeHeap::following_block(FreeBlock *b) { 340 return (FreeBlock*)(((address)b) + _segment_size * b->length()); 341 } 342 343 // Inserts block b after a 344 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) { 345 assert(a != NULL && b != NULL, "must be real pointers"); 346 347 // Link b into the list after a 348 b->set_link(a->link()); 349 a->set_link(b); 350 351 // See if we can merge blocks 352 merge_right(b); // Try to make b bigger 353 merge_right(a); // Try to make a include b 354 } 355 356 // Try to merge this block with the following block 357 void CodeHeap::merge_right(FreeBlock *a) { 358 assert(a->free(), "must be a free block"); 359 if (following_block(a) == a->link()) { 360 assert(a->link() != NULL && a->link()->free(), "must be free too"); 361 // Update block a to include the following block 362 a->set_length(a->length() + a->link()->length()); 363 a->set_link(a->link()->link()); 364 // Update find_start map 365 size_t beg = segment_for(a); 366 mark_segmap_as_used(beg, beg + a->length()); 367 } 368 } 369 370 void CodeHeap::add_to_freelist(HeapBlock *a) { 371 FreeBlock* b = (FreeBlock*)a; 372 assert(b != _freelist, "cannot be removed twice"); 373 374 // Mark as free and update free space count 375 _free_segments += b->length(); 376 b->set_free(); 377 378 // First element in list? 379 if (_freelist == NULL) { 380 _freelist = b; 381 b->set_link(NULL); 382 return; 383 } 384 385 // Scan for right place to put into list. List 386 // is sorted by increasing addresseses 387 FreeBlock* prev = NULL; 388 FreeBlock* cur = _freelist; 389 while(cur != NULL && cur < b) { 390 assert(prev == NULL || prev < cur, "must be ordered"); 391 prev = cur; 392 cur = cur->link(); 393 } 394 395 assert( (prev == NULL && b < _freelist) || 396 (prev < b && (cur == NULL || b < cur)), "list must be ordered"); 397 398 if (prev == NULL) { 399 // Insert first in list 400 b->set_link(_freelist); 401 _freelist = b; 402 merge_right(_freelist); 403 } else { 404 insert_after(prev, b); 405 } 406 } 407 408 // Search freelist for an entry on the list with the best fit 409 // Return NULL if no one was found 410 FreeBlock* CodeHeap::search_freelist(size_t length) { 411 FreeBlock *best_block = NULL; 412 FreeBlock *best_prev = NULL; 413 size_t best_length = 0; 414 415 // Search for smallest block which is bigger than length 416 FreeBlock *prev = NULL; 417 FreeBlock *cur = _freelist; 418 while(cur != NULL) { 419 size_t l = cur->length(); 420 if (l >= length && (best_block == NULL || best_length > l)) { 421 // Remember best block, its previous element, and its length 422 best_block = cur; 423 best_prev = prev; 424 best_length = best_block->length(); 425 } 426 427 // Next element in list 428 prev = cur; 429 cur = cur->link(); 430 } 431 432 if (best_block == NULL) { 433 // None found 434 return NULL; 435 } 436 437 assert((best_prev == NULL && _freelist == best_block ) || 438 (best_prev != NULL && best_prev->link() == best_block), "sanity check"); 439 440 // Exact (or at least good enough) fit. Remove from list. 441 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength. 442 if (best_length < length + CodeCacheMinBlockLength) { 443 length = best_length; 444 if (best_prev == NULL) { 445 assert(_freelist == best_block, "sanity check"); 446 _freelist = _freelist->link(); 447 } else { 448 // Unmap element 449 best_prev->set_link(best_block->link()); 450 } 451 } else { 452 // Truncate block and return a pointer to the following block 453 best_block->set_length(best_length - length); 454 best_block = following_block(best_block); 455 // Set used bit and length on new block 456 size_t beg = segment_for(best_block); 457 mark_segmap_as_used(beg, beg + length); 458 best_block->set_length(length); 459 } 460 461 best_block->set_used(); 462 _free_segments -= length; 463 return best_block; 464 } 465 466 //---------------------------------------------------------------------------- 467 // Non-product code 468 469 #ifndef PRODUCT 470 471 void CodeHeap::print() { 472 tty->print_cr("The Heap"); 473 } 474 475 #endif 476 477 void CodeHeap::verify() { 478 // Count the number of blocks on the freelist, and the amount of space 479 // represented. 480 int count = 0; 481 size_t len = 0; 482 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) { 483 len += b->length(); 484 count++; 485 } 486 487 // Verify that freelist contains the right amount of free space 488 // guarantee(len == _free_segments, "wrong freelist"); 489 490 // Verify that the number of free blocks is not out of hand. 491 static int free_block_threshold = 10000; 492 if (count > free_block_threshold) { 493 warning("CodeHeap: # of free blocks > %d", free_block_threshold); 494 // Double the warning limit 495 free_block_threshold *= 2; 496 } 497 498 // Verify that the freelist contains the same number of free blocks that is 499 // found on the full list. 500 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) { 501 if (h->free()) count--; 502 } 503 // guarantee(count == 0, "missing free blocks"); 504 }