1 /* 2 * Copyright (c) 1997, 2009, 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 "incls/_precompiled.incl" 26 # include "incls/_heap.cpp.incl" 27 28 29 size_t CodeHeap::header_size() { 30 return sizeof(HeapBlock); 31 } 32 33 34 // Implementation of Heap 35 36 CodeHeap::CodeHeap() { 37 _number_of_committed_segments = 0; 38 _number_of_reserved_segments = 0; 39 _segment_size = 0; 40 _log2_segment_size = 0; 41 _next_segment = 0; 42 _freelist = NULL; 43 _free_segments = 0; 44 } 45 46 47 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) { 48 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 49 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 50 // setup _segmap pointers for faster indexing 51 address p = (address)_segmap.low() + beg; 52 address q = (address)_segmap.low() + end; 53 // initialize interval 54 while (p < q) *p++ = 0xFF; 55 } 56 57 58 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) { 59 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds"); 60 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds"); 61 // setup _segmap pointers for faster indexing 62 address p = (address)_segmap.low() + beg; 63 address q = (address)_segmap.low() + end; 64 // initialize interval 65 int i = 0; 66 while (p < q) { 67 *p++ = i++; 68 if (i == 0xFF) i = 1; 69 } 70 } 71 72 73 static size_t align_to_page_size(size_t size) { 74 const size_t alignment = (size_t)os::vm_page_size(); 75 assert(is_power_of_2(alignment), "no kidding ???"); 76 return (size + alignment - 1) & ~(alignment - 1); 77 } 78 79 80 static size_t align_to_allocation_size(size_t size) { 81 const size_t alignment = (size_t)os::vm_allocation_granularity(); 82 assert(is_power_of_2(alignment), "no kidding ???"); 83 return (size + alignment - 1) & ~(alignment - 1); 84 } 85 86 87 void CodeHeap::on_code_mapping(char* base, size_t size) { 88 #ifdef LINUX 89 extern void linux_wrap_code(char* base, size_t size); 90 linux_wrap_code(base, size); 91 #endif 92 } 93 94 95 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size, 96 size_t segment_size) { 97 assert(reserved_size >= committed_size, "reserved < committed"); 98 assert(segment_size >= sizeof(FreeBlock), "segment size is too small"); 99 assert(is_power_of_2(segment_size), "segment_size must be a power of 2"); 100 101 _segment_size = segment_size; 102 _log2_segment_size = exact_log2(segment_size); 103 104 // Reserve and initialize space for _memory. 105 const size_t page_size = os::can_execute_large_page_memory() ? 106 os::page_size_for_region(committed_size, reserved_size, 8) : 107 os::vm_page_size(); 108 const size_t granularity = os::vm_allocation_granularity(); 109 const size_t r_align = MAX2(page_size, granularity); 110 const size_t r_size = align_size_up(reserved_size, r_align); 111 const size_t c_size = align_size_up(committed_size, page_size); 112 113 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 : 114 MAX2(page_size, granularity); 115 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0); 116 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size, 117 rs.base(), rs.size()); 118 if (!_memory.initialize(rs, c_size)) { 119 return false; 120 } 121 122 on_code_mapping(_memory.low(), _memory.committed_size()); 123 _number_of_committed_segments = number_of_segments(_memory.committed_size()); 124 _number_of_reserved_segments = number_of_segments(_memory.reserved_size()); 125 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 126 127 // reserve space for _segmap 128 if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) { 129 return false; 130 } 131 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map"); 132 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map"); 133 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking"); 134 135 // initialize remaining instance variables 136 clear(); 137 return true; 138 } 139 140 141 void CodeHeap::release() { 142 Unimplemented(); 143 } 144 145 146 bool CodeHeap::expand_by(size_t size) { 147 // expand _memory space 148 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size(); 149 if (dm > 0) { 150 char* base = _memory.low() + _memory.committed_size(); 151 if (!_memory.expand_by(dm)) return false; 152 on_code_mapping(base, dm); 153 size_t i = _number_of_committed_segments; 154 _number_of_committed_segments = number_of_segments(_memory.committed_size()); 155 assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change"); 156 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking"); 157 // expand _segmap space 158 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size(); 159 if (ds > 0) { 160 if (!_segmap.expand_by(ds)) return false; 161 } 162 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking"); 163 // initialize additional segmap entries 164 mark_segmap_as_free(i, _number_of_committed_segments); 165 } 166 return true; 167 } 168 169 170 void CodeHeap::shrink_by(size_t size) { 171 Unimplemented(); 172 } 173 174 175 void CodeHeap::clear() { 176 _next_segment = 0; 177 mark_segmap_as_free(0, _number_of_committed_segments); 178 } 179 180 181 void* CodeHeap::allocate(size_t size) { 182 size_t length = number_of_segments(size + sizeof(HeapBlock)); 183 assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList"); 184 185 // First check if we can satify request from freelist 186 debug_only(verify()); 187 HeapBlock* block = search_freelist(length); 188 debug_only(if (VerifyCodeCacheOften) verify()); 189 if (block != NULL) { 190 assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check"); 191 assert(!block->free(), "must be marked free"); 192 #ifdef ASSERT 193 memset((void *)block->allocated_space(), badCodeHeapNewVal, size); 194 #endif 195 return block->allocated_space(); 196 } 197 198 if (length < CodeCacheMinBlockLength) { 199 length = CodeCacheMinBlockLength; 200 } 201 if (_next_segment + length <= _number_of_committed_segments) { 202 mark_segmap_as_used(_next_segment, _next_segment + length); 203 HeapBlock* b = block_at(_next_segment); 204 b->initialize(length); 205 _next_segment += length; 206 #ifdef ASSERT 207 memset((void *)b->allocated_space(), badCodeHeapNewVal, size); 208 #endif 209 return b->allocated_space(); 210 } else { 211 return NULL; 212 } 213 } 214 215 216 void CodeHeap::deallocate(void* p) { 217 assert(p == find_start(p), "illegal deallocation"); 218 // Find start of HeapBlock 219 HeapBlock* b = (((HeapBlock *)p) - 1); 220 assert(b->allocated_space() == p, "sanity check"); 221 #ifdef ASSERT 222 memset((void *)b->allocated_space(), 223 badCodeHeapFreeVal, 224 size(b->length()) - sizeof(HeapBlock)); 225 #endif 226 add_to_freelist(b); 227 228 debug_only(if (VerifyCodeCacheOften) verify()); 229 } 230 231 232 void* CodeHeap::find_start(void* p) const { 233 if (!contains(p)) { 234 return NULL; 235 } 236 size_t i = segment_for(p); 237 address b = (address)_segmap.low(); 238 if (b[i] == 0xFF) { 239 return NULL; 240 } 241 while (b[i] > 0) i -= (int)b[i]; 242 HeapBlock* h = block_at(i); 243 if (h->free()) { 244 return NULL; 245 } 246 return h->allocated_space(); 247 } 248 249 250 size_t CodeHeap::alignment_unit() const { 251 // this will be a power of two 252 return _segment_size; 253 } 254 255 256 size_t CodeHeap::alignment_offset() const { 257 // The lowest address in any allocated block will be 258 // equal to alignment_offset (mod alignment_unit). 259 return sizeof(HeapBlock) & (_segment_size - 1); 260 } 261 262 // Finds the next free heapblock. If the current one is free, that it returned 263 void* CodeHeap::next_free(HeapBlock *b) const { 264 // Since free blocks are merged, there is max. on free block 265 // between two used ones 266 if (b != NULL && b->free()) b = next_block(b); 267 assert(b == NULL || !b->free(), "must be in use or at end of heap"); 268 return (b == NULL) ? NULL : b->allocated_space(); 269 } 270 271 // Returns the first used HeapBlock 272 HeapBlock* CodeHeap::first_block() const { 273 if (_next_segment > 0) 274 return block_at(0); 275 return NULL; 276 } 277 278 HeapBlock *CodeHeap::block_start(void *q) const { 279 HeapBlock* b = (HeapBlock*)find_start(q); 280 if (b == NULL) return NULL; 281 return b - 1; 282 } 283 284 // Returns the next Heap block an offset into one 285 HeapBlock* CodeHeap::next_block(HeapBlock *b) const { 286 if (b == NULL) return NULL; 287 size_t i = segment_for(b) + b->length(); 288 if (i < _next_segment) 289 return block_at(i); 290 return NULL; 291 } 292 293 294 // Returns current capacity 295 size_t CodeHeap::capacity() const { 296 return _memory.committed_size(); 297 } 298 299 size_t CodeHeap::max_capacity() const { 300 return _memory.reserved_size(); 301 } 302 303 size_t CodeHeap::allocated_capacity() const { 304 // Start with the committed size in _memory; 305 size_t l = _memory.committed_size(); 306 307 // Subtract the committed, but unused, segments 308 l -= size(_number_of_committed_segments - _next_segment); 309 310 // Subtract the size of the freelist 311 l -= size(_free_segments); 312 313 return l; 314 } 315 316 // Free list management 317 318 FreeBlock *CodeHeap::following_block(FreeBlock *b) { 319 return (FreeBlock*)(((address)b) + _segment_size * b->length()); 320 } 321 322 // Inserts block b after a 323 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) { 324 assert(a != NULL && b != NULL, "must be real pointers"); 325 326 // Link b into the list after a 327 b->set_link(a->link()); 328 a->set_link(b); 329 330 // See if we can merge blocks 331 merge_right(b); // Try to make b bigger 332 merge_right(a); // Try to make a include b 333 } 334 335 // Try to merge this block with the following block 336 void CodeHeap::merge_right(FreeBlock *a) { 337 assert(a->free(), "must be a free block"); 338 if (following_block(a) == a->link()) { 339 assert(a->link() != NULL && a->link()->free(), "must be free too"); 340 // Update block a to include the following block 341 a->set_length(a->length() + a->link()->length()); 342 a->set_link(a->link()->link()); 343 // Update find_start map 344 size_t beg = segment_for(a); 345 mark_segmap_as_used(beg, beg + a->length()); 346 } 347 } 348 349 void CodeHeap::add_to_freelist(HeapBlock *a) { 350 FreeBlock* b = (FreeBlock*)a; 351 assert(b != _freelist, "cannot be removed twice"); 352 353 // Mark as free and update free space count 354 _free_segments += b->length(); 355 b->set_free(); 356 357 // First element in list? 358 if (_freelist == NULL) { 359 _freelist = b; 360 b->set_link(NULL); 361 return; 362 } 363 364 // Scan for right place to put into list. List 365 // is sorted by increasing addresseses 366 FreeBlock* prev = NULL; 367 FreeBlock* cur = _freelist; 368 while(cur != NULL && cur < b) { 369 assert(prev == NULL || prev < cur, "must be ordered"); 370 prev = cur; 371 cur = cur->link(); 372 } 373 374 assert( (prev == NULL && b < _freelist) || 375 (prev < b && (cur == NULL || b < cur)), "list must be ordered"); 376 377 if (prev == NULL) { 378 // Insert first in list 379 b->set_link(_freelist); 380 _freelist = b; 381 merge_right(_freelist); 382 } else { 383 insert_after(prev, b); 384 } 385 } 386 387 // Search freelist for an entry on the list with the best fit 388 // Return NULL if no one was found 389 FreeBlock* CodeHeap::search_freelist(size_t length) { 390 FreeBlock *best_block = NULL; 391 FreeBlock *best_prev = NULL; 392 size_t best_length = 0; 393 394 // Search for smallest block which is bigger than length 395 FreeBlock *prev = NULL; 396 FreeBlock *cur = _freelist; 397 while(cur != NULL) { 398 size_t l = cur->length(); 399 if (l >= length && (best_block == NULL || best_length > l)) { 400 // Remember best block, its previous element, and its length 401 best_block = cur; 402 best_prev = prev; 403 best_length = best_block->length(); 404 } 405 406 // Next element in list 407 prev = cur; 408 cur = cur->link(); 409 } 410 411 if (best_block == NULL) { 412 // None found 413 return NULL; 414 } 415 416 assert((best_prev == NULL && _freelist == best_block ) || 417 (best_prev != NULL && best_prev->link() == best_block), "sanity check"); 418 419 // Exact (or at least good enough) fit. Remove from list. 420 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength. 421 if (best_length < length + CodeCacheMinBlockLength) { 422 length = best_length; 423 if (best_prev == NULL) { 424 assert(_freelist == best_block, "sanity check"); 425 _freelist = _freelist->link(); 426 } else { 427 // Unmap element 428 best_prev->set_link(best_block->link()); 429 } 430 } else { 431 // Truncate block and return a pointer to the following block 432 best_block->set_length(best_length - length); 433 best_block = following_block(best_block); 434 // Set used bit and length on new block 435 size_t beg = segment_for(best_block); 436 mark_segmap_as_used(beg, beg + length); 437 best_block->set_length(length); 438 } 439 440 best_block->set_used(); 441 _free_segments -= length; 442 return best_block; 443 } 444 445 //---------------------------------------------------------------------------- 446 // Non-product code 447 448 #ifndef PRODUCT 449 450 void CodeHeap::print() { 451 tty->print_cr("The Heap"); 452 } 453 454 #endif 455 456 void CodeHeap::verify() { 457 // Count the number of blocks on the freelist, and the amount of space 458 // represented. 459 int count = 0; 460 size_t len = 0; 461 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) { 462 len += b->length(); 463 count++; 464 } 465 466 // Verify that freelist contains the right amount of free space 467 // guarantee(len == _free_segments, "wrong freelist"); 468 469 // Verify that the number of free blocks is not out of hand. 470 static int free_block_threshold = 10000; 471 if (count > free_block_threshold) { 472 warning("CodeHeap: # of free blocks > %d", free_block_threshold); 473 // Double the warning limit 474 free_block_threshold *= 2; 475 } 476 477 // Verify that the freelist contains the same number of free blocks that is 478 // found on the full list. 479 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) { 480 if (h->free()) count--; 481 } 482 // guarantee(count == 0, "missing free blocks"); 483 }