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 const size_t min_pages = 8;
103 page_size = MIN2(os::page_size_for_region_aligned(committed_size, min_pages),
104 os::page_size_for_region_aligned(reserved_size, min_pages));
105 }
106
107 const size_t granularity = os::vm_allocation_granularity();
108 const size_t r_align = MAX2(page_size, granularity);
109 const size_t r_size = align_size_up(reserved_size, r_align);
110 const size_t c_size = align_size_up(committed_size, page_size);
111
112 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
113 MAX2(page_size, granularity);
114 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);
115 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
116 rs.base(), rs.size());
117 if (!_memory.initialize(rs, c_size)) {
118 return false;
119 }
120
121 on_code_mapping(_memory.low(), _memory.committed_size());
122 _number_of_committed_segments = size_to_segments(_memory.committed_size());
123 _number_of_reserved_segments = size_to_segments(_memory.reserved_size());
124 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
125 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);
126 const size_t reserved_segments_size = align_size_up(_number_of_reserved_segments, reserved_segments_alignment);
127 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);
128
129 // reserve space for _segmap
130 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {
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 = size_to_segments(_memory.committed_size());
160 assert(_number_of_reserved_segments == size_to_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 instance_size, bool is_critical) {
187 size_t number_of_segments = size_to_segments(instance_size + sizeof(HeapBlock));
188 assert(segments_to_size(number_of_segments) >= 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(number_of_segments, is_critical);
193 debug_only(if (VerifyCodeCacheOften) verify());
194 if (block != NULL) {
195 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check");
196 assert(!block->free(), "must be marked free");
197 #ifdef ASSERT
198 memset((void *)block->allocated_space(), badCodeHeapNewVal, instance_size);
199 #endif
200 return block->allocated_space();
201 }
202
203 // Ensure minimum size for allocation to the heap.
204 if (number_of_segments < CodeCacheMinBlockLength) {
205 number_of_segments = CodeCacheMinBlockLength;
206 }
207
208 if (!is_critical) {
209 // Make sure the allocation fits in the unallocated heap without using
210 // the CodeCacheMimimumFreeSpace that is reserved for critical allocations.
211 if (segments_to_size(number_of_segments) > (heap_unallocated_capacity() - CodeCacheMinimumFreeSpace)) {
212 // Fail allocation
213 return NULL;
214 }
215 }
216
217 if (_next_segment + number_of_segments <= _number_of_committed_segments) {
218 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);
219 HeapBlock* b = block_at(_next_segment);
220 b->initialize(number_of_segments);
221 _next_segment += number_of_segments;
222 #ifdef ASSERT
223 memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size);
224 #endif
225 return b->allocated_space();
226 } else {
227 return NULL;
228 }
229 }
230
231
232 void CodeHeap::deallocate(void* p) {
233 assert(p == find_start(p), "illegal deallocation");
234 // Find start of HeapBlock
235 HeapBlock* b = (((HeapBlock *)p) - 1);
236 assert(b->allocated_space() == p, "sanity check");
237 #ifdef ASSERT
238 memset((void *)b->allocated_space(),
239 badCodeHeapFreeVal,
240 segments_to_size(b->length()) - sizeof(HeapBlock));
241 #endif
242 add_to_freelist(b);
243
244 debug_only(if (VerifyCodeCacheOften) verify());
245 }
246
247
248 void* CodeHeap::find_start(void* p) const {
249 if (!contains(p)) {
250 return NULL;
251 }
252 size_t i = segment_for(p);
253 address b = (address)_segmap.low();
254 if (b[i] == 0xFF) {
255 return NULL;
256 }
257 while (b[i] > 0) i -= (int)b[i];
258 HeapBlock* h = block_at(i);
259 if (h->free()) {
260 return NULL;
261 }
262 return h->allocated_space();
263 }
264
265
266 size_t CodeHeap::alignment_unit() const {
267 // this will be a power of two
268 return _segment_size;
269 }
270
271
272 size_t CodeHeap::alignment_offset() const {
273 // The lowest address in any allocated block will be
274 // equal to alignment_offset (mod alignment_unit).
275 return sizeof(HeapBlock) & (_segment_size - 1);
276 }
277
278 // Finds the next free heapblock. If the current one is free, that it returned
279 void* CodeHeap::next_free(HeapBlock *b) const {
280 // Since free blocks are merged, there is max. on free block
281 // between two used ones
282 if (b != NULL && b->free()) b = next_block(b);
283 assert(b == NULL || !b->free(), "must be in use or at end of heap");
284 return (b == NULL) ? NULL : b->allocated_space();
285 }
286
287 // Returns the first used HeapBlock
288 HeapBlock* CodeHeap::first_block() const {
289 if (_next_segment > 0)
290 return block_at(0);
291 return NULL;
292 }
293
294 HeapBlock *CodeHeap::block_start(void *q) const {
295 HeapBlock* b = (HeapBlock*)find_start(q);
296 if (b == NULL) return NULL;
297 return b - 1;
298 }
299
300 // Returns the next Heap block an offset into one
301 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
302 if (b == NULL) return NULL;
303 size_t i = segment_for(b) + b->length();
304 if (i < _next_segment)
305 return block_at(i);
306 return NULL;
307 }
308
309
310 // Returns current capacity
311 size_t CodeHeap::capacity() const {
312 return _memory.committed_size();
313 }
314
315 size_t CodeHeap::max_capacity() const {
316 return _memory.reserved_size();
317 }
318
319 size_t CodeHeap::allocated_capacity() const {
320 // size of used heap - size on freelist
321 return segments_to_size(_next_segment - _freelist_segments);
322 }
323
324 // Returns size of the unallocated heap block
325 size_t CodeHeap::heap_unallocated_capacity() const {
326 // Total number of segments - number currently used
327 return segments_to_size(_number_of_reserved_segments - _next_segment);
328 }
329
330 // Free list management
331
332 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
333 return (FreeBlock*)(((address)b) + _segment_size * b->length());
334 }
335
336 // Inserts block b after a
337 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
338 assert(a != NULL && b != NULL, "must be real pointers");
339
340 // Link b into the list after a
341 b->set_link(a->link());
342 a->set_link(b);
343
344 // See if we can merge blocks
345 merge_right(b); // Try to make b bigger
346 merge_right(a); // Try to make a include b
347 }
348
349 // Try to merge this block with the following block
350 void CodeHeap::merge_right(FreeBlock *a) {
351 assert(a->free(), "must be a free block");
352 if (following_block(a) == a->link()) {
353 assert(a->link() != NULL && a->link()->free(), "must be free too");
354 // Update block a to include the following block
355 a->set_length(a->length() + a->link()->length());
356 a->set_link(a->link()->link());
357 // Update find_start map
358 size_t beg = segment_for(a);
359 mark_segmap_as_used(beg, beg + a->length());
360 }
361 }
362
363 void CodeHeap::add_to_freelist(HeapBlock *a) {
364 FreeBlock* b = (FreeBlock*)a;
365 assert(b != _freelist, "cannot be removed twice");
366
367 // Mark as free and update free space count
368 _freelist_segments += b->length();
369 b->set_free();
370
371 // First element in list?
372 if (_freelist == NULL) {
373 _freelist = b;
374 b->set_link(NULL);
375 return;
376 }
377
378 // Scan for right place to put into list. List
379 // is sorted by increasing addresseses
380 FreeBlock* prev = NULL;
381 FreeBlock* cur = _freelist;
382 while(cur != NULL && cur < b) {
383 assert(prev == NULL || prev < cur, "must be ordered");
384 prev = cur;
385 cur = cur->link();
386 }
387
388 assert( (prev == NULL && b < _freelist) ||
389 (prev < b && (cur == NULL || b < cur)), "list must be ordered");
390
391 if (prev == NULL) {
392 // Insert first in list
393 b->set_link(_freelist);
394 _freelist = b;
395 merge_right(_freelist);
396 } else {
397 insert_after(prev, b);
398 }
399 }
400
401 // Search freelist for an entry on the list with the best fit
402 // Return NULL if no one was found
403 FreeBlock* CodeHeap::search_freelist(size_t length, bool is_critical) {
404 FreeBlock *best_block = NULL;
405 FreeBlock *best_prev = NULL;
406 size_t best_length = 0;
407
408 // Search for smallest block which is bigger than length
409 FreeBlock *prev = NULL;
410 FreeBlock *cur = _freelist;
411 while(cur != NULL) {
412 size_t l = cur->length();
413 if (l >= length && (best_block == NULL || best_length > l)) {
414
415 // Non critical allocations are not allowed to use the last part of the code heap.
416 if (!is_critical) {
417 // Make sure the end of the allocation doesn't cross into the last part of the code heap
418 if (((size_t)cur + length) > ((size_t)high_boundary() - CodeCacheMinimumFreeSpace)) {
419 // the freelist is sorted by address - if one fails, all consecutive will also fail.
420 break;
421 }
422 }
423
424 // Remember best block, its previous element, and its length
425 best_block = cur;
426 best_prev = prev;
427 best_length = best_block->length();
428 }
429
430 // Next element in list
431 prev = cur;
432 cur = cur->link();
433 }
434
435 if (best_block == NULL) {
436 // None found
437 return NULL;
438 }
439
440 assert((best_prev == NULL && _freelist == best_block ) ||
441 (best_prev != NULL && best_prev->link() == best_block), "sanity check");
442
443 // Exact (or at least good enough) fit. Remove from list.
444 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
445 if (best_length < length + CodeCacheMinBlockLength) {
446 length = best_length;
447 if (best_prev == NULL) {
448 assert(_freelist == best_block, "sanity check");
449 _freelist = _freelist->link();
450 } else {
451 // Unmap element
452 best_prev->set_link(best_block->link());
453 }
454 } else {
455 // Truncate block and return a pointer to the following block
456 best_block->set_length(best_length - length);
457 best_block = following_block(best_block);
458 // Set used bit and length on new block
459 size_t beg = segment_for(best_block);
460 mark_segmap_as_used(beg, beg + length);
461 best_block->set_length(length);
462 }
463
464 best_block->set_used();
465 _freelist_segments -= length;
466 return best_block;
467 }
468
469 //----------------------------------------------------------------------------
470 // Non-product code
471
472 #ifndef PRODUCT
473
474 void CodeHeap::print() {
475 tty->print_cr("The Heap");
476 }
477
478 #endif
479
480 void CodeHeap::verify() {
481 // Count the number of blocks on the freelist, and the amount of space
482 // represented.
483 int count = 0;
484 size_t len = 0;
485 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
486 len += b->length();
487 count++;
488 }
489
490 // Verify that freelist contains the right amount of free space
491 // guarantee(len == _freelist_segments, "wrong freelist");
492
493 // Verify that the number of free blocks is not out of hand.
494 static int free_block_threshold = 10000;
495 if (count > free_block_threshold) {
496 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
497 // Double the warning limit
498 free_block_threshold *= 2;
499 }
500
501 // Verify that the freelist contains the same number of free blocks that is
502 // found on the full list.
503 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
504 if (h->free()) count--;
505 }
506 // guarantee(count == 0, "missing free blocks");
507 }