1 /*
2 * Copyright (c) 1997, 2015, 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 #include "utilities/align.hpp"
31
32 size_t CodeHeap::header_size() {
33 return sizeof(HeapBlock);
34 }
35
36
37 // Implementation of Heap
38
39 CodeHeap::CodeHeap(const char* name, const int code_blob_type)
40 : _code_blob_type(code_blob_type) {
41 _name = name;
42 _number_of_committed_segments = 0;
43 _number_of_reserved_segments = 0;
44 _segment_size = 0;
45 _log2_segment_size = 0;
46 _next_segment = 0;
47 _freelist = NULL;
48 _freelist_segments = 0;
49 _freelist_length = 0;
50 _max_allocated_capacity = 0;
51 _blob_count = 0;
52 _nmethod_count = 0;
53 _adapter_count = 0;
54 _full_count = 0;
55 }
56
57
58 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
59 assert( 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 while (p < q) *p++ = free_sentinel;
66 }
67
68
69 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
70 assert( beg < _number_of_committed_segments, "interval begin out of bounds");
71 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
72 // setup _segmap pointers for faster indexing
73 address p = (address)_segmap.low() + beg;
74 address q = (address)_segmap.low() + end;
75 // initialize interval
76 int i = 0;
77 while (p < q) {
78 *p++ = i++;
79 if (i == free_sentinel) i = 1;
80 }
81 }
82
83
84 static size_t align_to_page_size(size_t size) {
85 const size_t alignment = (size_t)os::vm_page_size();
86 assert(is_power_of_2(alignment), "no kidding ???");
87 return (size + alignment - 1) & ~(alignment - 1);
88 }
89
90
91 void CodeHeap::on_code_mapping(char* base, size_t size) {
92 #ifdef LINUX
93 extern void linux_wrap_code(char* base, size_t size);
94 linux_wrap_code(base, size);
95 #endif
96 }
97
98
99 bool CodeHeap::reserve(ReservedSpace rs, size_t committed_size, size_t segment_size) {
100 assert(rs.size() >= committed_size, "reserved < committed");
101 assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
102 assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
103
104 _segment_size = segment_size;
105 _log2_segment_size = exact_log2(segment_size);
106
107 // Reserve and initialize space for _memory.
108 size_t page_size = os::vm_page_size();
109 if (os::can_execute_large_page_memory()) {
110 const size_t min_pages = 8;
111 page_size = MIN2(os::page_size_for_region_aligned(committed_size, min_pages),
112 os::page_size_for_region_aligned(rs.size(), min_pages));
113 }
114
115 const size_t granularity = os::vm_allocation_granularity();
116 const size_t c_size = align_up(committed_size, page_size);
117
118 os::trace_page_sizes(_name, committed_size, rs.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 = size_to_segments(_memory.committed_size());
126 _number_of_reserved_segments = size_to_segments(_memory.reserved_size());
127 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
128 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);
129 const size_t reserved_segments_size = align_up(_number_of_reserved_segments, reserved_segments_alignment);
130 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);
131
132 // reserve space for _segmap
133 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {
134 return false;
135 }
136
137 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode);
138
139 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
140 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
141 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
142
143 // initialize remaining instance variables
144 clear();
145 return true;
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 // Use at least the available uncommitted space if 'size' is larger
154 if (_memory.uncommitted_size() != 0 && dm > _memory.uncommitted_size()) {
155 dm = _memory.uncommitted_size();
156 }
157 char* base = _memory.low() + _memory.committed_size();
158 if (!_memory.expand_by(dm)) return false;
159 on_code_mapping(base, dm);
160 size_t i = _number_of_committed_segments;
161 _number_of_committed_segments = size_to_segments(_memory.committed_size());
162 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change");
163 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
164 // expand _segmap space
165 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
166 if ((ds > 0) && !_segmap.expand_by(ds)) {
167 return false;
168 }
169 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
170 // initialize additional segmap entries
171 mark_segmap_as_free(i, _number_of_committed_segments);
172 }
173 return true;
174 }
175
176 void CodeHeap::clear() {
177 _next_segment = 0;
178 mark_segmap_as_free(0, _number_of_committed_segments);
179 }
180
181
182 void* CodeHeap::allocate(size_t instance_size) {
183 size_t number_of_segments = size_to_segments(instance_size + header_size());
184 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");
185
186 // First check if we can satisfy request from freelist
187 NOT_PRODUCT(verify());
188 HeapBlock* block = search_freelist(number_of_segments);
189 NOT_PRODUCT(verify());
190
191 if (block != NULL) {
192 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check");
193 assert(!block->free(), "must be marked free");
194 guarantee((char*) block >= _memory.low_boundary() && (char*) block < _memory.high(),
195 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
196 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
197 p2i(block), p2i(_memory.low_boundary()), p2i(_memory.high()));
198 DEBUG_ONLY(memset((void*)block->allocated_space(), badCodeHeapNewVal, instance_size));
199 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
200 _blob_count++;
201 return block->allocated_space();
202 }
203
204 // Ensure minimum size for allocation to the heap.
205 number_of_segments = MAX2((int)CodeCacheMinBlockLength, (int)number_of_segments);
206
207 if (_next_segment + number_of_segments <= _number_of_committed_segments) {
208 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);
209 HeapBlock* b = block_at(_next_segment);
210 b->initialize(number_of_segments);
211 _next_segment += number_of_segments;
212 guarantee((char*) b >= _memory.low_boundary() && (char*) block < _memory.high(),
213 "The newly allocated block " INTPTR_FORMAT " is not within the heap "
214 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
215 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
216 DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size));
217 _max_allocated_capacity = MAX2(_max_allocated_capacity, allocated_capacity());
218 _blob_count++;
219 return b->allocated_space();
220 } else {
221 return NULL;
222 }
223 }
224
225 void CodeHeap::deallocate_tail(void* p, size_t used_size) {
226 assert(p == find_start(p), "illegal deallocation");
227 // Find start of HeapBlock
228 HeapBlock* b = (((HeapBlock *)p) - 1);
229 assert(b->allocated_space() == p, "sanity check");
230 size_t used_number_of_segments = size_to_segments(used_size + header_size());
231 size_t actual_number_of_segments = b->length();
232 guarantee(used_number_of_segments <= actual_number_of_segments, "Must be!");
233 guarantee(b == block_at(_next_segment - actual_number_of_segments), "Intermediate allocation!");
234 size_t number_of_segments_to_deallocate = actual_number_of_segments - used_number_of_segments;
235 _next_segment -= number_of_segments_to_deallocate;
236 mark_segmap_as_free(_next_segment, _next_segment + number_of_segments_to_deallocate);
237 b->initialize(used_number_of_segments);
238 }
239
240 void CodeHeap::deallocate(void* p) {
241 assert(p == find_start(p), "illegal deallocation");
242 // Find start of HeapBlock
243 HeapBlock* b = (((HeapBlock *)p) - 1);
244 assert(b->allocated_space() == p, "sanity check");
245 guarantee((char*) b >= _memory.low_boundary() && (char*) b < _memory.high(),
246 "The block to be deallocated " INTPTR_FORMAT " is not within the heap "
247 "starting with " INTPTR_FORMAT " and ending with " INTPTR_FORMAT,
248 p2i(b), p2i(_memory.low_boundary()), p2i(_memory.high()));
249 DEBUG_ONLY(memset((void *)b->allocated_space(), badCodeHeapFreeVal,
250 segments_to_size(b->length()) - sizeof(HeapBlock)));
251 add_to_freelist(b);
252 NOT_PRODUCT(verify());
253 }
254
255 /**
256 * Uses segment map to find the the start (header) of a nmethod. This works as follows:
257 * The memory of the code cache is divided into 'segments'. The size of a segment is
258 * determined by -XX:CodeCacheSegmentSize=XX. Allocation in the code cache can only
259 * happen at segment boundaries. A pointer in the code cache can be mapped to a segment
260 * by calling segment_for(addr). Each time memory is requested from the code cache,
261 * the segmap is updated accordingly. See the following example, which illustrates the
262 * state of code cache and the segment map: (seg -> segment, nm ->nmethod)
263 *
264 * code cache segmap
265 * ----------- ---------
266 * seg 1 | nm 1 | -> | 0 |
267 * seg 2 | nm 1 | -> | 1 |
268 * ... | nm 1 | -> | .. |
269 * seg m | nm 2 | -> | 0 |
270 * seg m+1 | nm 2 | -> | 1 |
271 * ... | nm 2 | -> | 2 |
272 * ... | nm 2 | -> | .. |
273 * ... | nm 2 | -> | 0xFE |
274 * seg m+n | nm 2 | -> | 1 |
275 * ... | nm 2 | -> | |
276 *
277 * A value of '0' in the segmap indicates that this segment contains the beginning of
278 * an nmethod. Let's walk through a simple example: If we want to find the start of
279 * an nmethod that falls into seg 2, we read the value of the segmap[2]. The value
280 * is an offset that points to the segment that contains the start of the nmethod.
281 * Another example: If we want to get the start of nm 2, and we happen to get a pointer
282 * that points to seg m+n, we first read seg[n+m], which returns '1'. So we have to
283 * do one more read of the segmap[m+n-1] to finally get the segment header.
284 */
285 void* CodeHeap::find_start(void* p) const {
286 if (!contains(p)) {
287 return NULL;
288 }
289 size_t seg_idx = segment_for(p);
290 address seg_map = (address)_segmap.low();
291 if (is_segment_unused(seg_map[seg_idx])) {
292 return NULL;
293 }
294 while (seg_map[seg_idx] > 0) {
295 seg_idx -= (int)seg_map[seg_idx];
296 }
297
298 HeapBlock* h = block_at(seg_idx);
299 if (h->free()) {
300 return NULL;
301 }
302 return h->allocated_space();
303 }
304
305 CodeBlob* CodeHeap::find_blob_unsafe(void* start) const {
306 CodeBlob* result = (CodeBlob*)CodeHeap::find_start(start);
307 if (result != NULL && result->blob_contains((address)start)) {
308 return result;
309 }
310 return NULL;
311 }
312
313 size_t CodeHeap::alignment_unit() const {
314 // this will be a power of two
315 return _segment_size;
316 }
317
318
319 size_t CodeHeap::alignment_offset() const {
320 // The lowest address in any allocated block will be
321 // equal to alignment_offset (mod alignment_unit).
322 return sizeof(HeapBlock) & (_segment_size - 1);
323 }
324
325 // Returns the current block if available and used.
326 // If not, it returns the subsequent block (if available), NULL otherwise.
327 // Free blocks are merged, therefore there is at most one free block
328 // between two used ones. As a result, the subsequent block (if available) is
329 // guaranteed to be used.
330 void* CodeHeap::next_used(HeapBlock* b) const {
331 if (b != NULL && b->free()) b = next_block(b);
332 assert(b == NULL || !b->free(), "must be in use or at end of heap");
333 return (b == NULL) ? NULL : b->allocated_space();
334 }
335
336 // Returns the first used HeapBlock
337 HeapBlock* CodeHeap::first_block() const {
338 if (_next_segment > 0)
339 return block_at(0);
340 return NULL;
341 }
342
343 HeapBlock* CodeHeap::block_start(void* q) const {
344 HeapBlock* b = (HeapBlock*)find_start(q);
345 if (b == NULL) return NULL;
346 return b - 1;
347 }
348
349 // Returns the next Heap block an offset into one
350 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
351 if (b == NULL) return NULL;
352 size_t i = segment_for(b) + b->length();
353 if (i < _next_segment)
354 return block_at(i);
355 return NULL;
356 }
357
358
359 // Returns current capacity
360 size_t CodeHeap::capacity() const {
361 return _memory.committed_size();
362 }
363
364 size_t CodeHeap::max_capacity() const {
365 return _memory.reserved_size();
366 }
367
368 int CodeHeap::allocated_segments() const {
369 return (int)_next_segment;
370 }
371
372 size_t CodeHeap::allocated_capacity() const {
373 // size of used heap - size on freelist
374 return segments_to_size(_next_segment - _freelist_segments);
375 }
376
377 // Returns size of the unallocated heap block
378 size_t CodeHeap::heap_unallocated_capacity() const {
379 // Total number of segments - number currently used
380 return segments_to_size(_number_of_reserved_segments - _next_segment);
381 }
382
383 // Free list management
384
385 FreeBlock* CodeHeap::following_block(FreeBlock *b) {
386 return (FreeBlock*)(((address)b) + _segment_size * b->length());
387 }
388
389 // Inserts block b after a
390 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
391 assert(a != NULL && b != NULL, "must be real pointers");
392
393 // Link b into the list after a
394 b->set_link(a->link());
395 a->set_link(b);
396
397 // See if we can merge blocks
398 merge_right(b); // Try to make b bigger
399 merge_right(a); // Try to make a include b
400 }
401
402 // Try to merge this block with the following block
403 bool CodeHeap::merge_right(FreeBlock* a) {
404 assert(a->free(), "must be a free block");
405 if (following_block(a) == a->link()) {
406 assert(a->link() != NULL && a->link()->free(), "must be free too");
407 // Update block a to include the following block
408 a->set_length(a->length() + a->link()->length());
409 a->set_link(a->link()->link());
410 // Update find_start map
411 size_t beg = segment_for(a);
412 mark_segmap_as_used(beg, beg + a->length());
413 _freelist_length--;
414 return true;
415 }
416 return false;
417 }
418
419
420 void CodeHeap::add_to_freelist(HeapBlock* a) {
421 FreeBlock* b = (FreeBlock*)a;
422 _freelist_length++;
423
424 assert(b != _freelist, "cannot be removed twice");
425
426
427 // Mark as free and update free space count
428 _freelist_segments += b->length();
429 b->set_free();
430
431 // First element in list?
432 if (_freelist == NULL) {
433 _freelist = b;
434 b->set_link(NULL);
435 return;
436 }
437
438 // Since the freelist is ordered (smaller addresses -> larger addresses) and the
439 // element we want to insert into the freelist has a smaller address than the first
440 // element, we can simply add 'b' as the first element and we are done.
441 if (b < _freelist) {
442 // Insert first in list
443 b->set_link(_freelist);
444 _freelist = b;
445 merge_right(_freelist);
446 return;
447 }
448
449 // Scan for right place to put into list. List
450 // is sorted by increasing addresses
451 FreeBlock* prev = _freelist;
452 FreeBlock* cur = _freelist->link();
453 while(cur != NULL && cur < b) {
454 assert(prev < cur, "Freelist must be ordered");
455 prev = cur;
456 cur = cur->link();
457 }
458 assert((prev < b) && (cur == NULL || b < cur), "free-list must be ordered");
459 insert_after(prev, b);
460 }
461
462 /**
463 * Search freelist for an entry on the list with the best fit.
464 * @return NULL, if no one was found
465 */
466 FreeBlock* CodeHeap::search_freelist(size_t length) {
467 FreeBlock* found_block = NULL;
468 FreeBlock* found_prev = NULL;
469 size_t found_length = 0;
470
471 FreeBlock* prev = NULL;
472 FreeBlock* cur = _freelist;
473
474 // Search for first block that fits
475 while(cur != NULL) {
476 if (cur->length() >= length) {
477 // Remember block, its previous element, and its length
478 found_block = cur;
479 found_prev = prev;
480 found_length = found_block->length();
481
482 break;
483 }
484 // Next element in list
485 prev = cur;
486 cur = cur->link();
487 }
488
489 if (found_block == NULL) {
490 // None found
491 return NULL;
492 }
493
494 // Exact (or at least good enough) fit. Remove from list.
495 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
496 if (found_length - length < CodeCacheMinBlockLength) {
497 _freelist_length--;
498 length = found_length;
499 if (found_prev == NULL) {
500 assert(_freelist == found_block, "sanity check");
501 _freelist = _freelist->link();
502 } else {
503 assert((found_prev->link() == found_block), "sanity check");
504 // Unmap element
505 found_prev->set_link(found_block->link());
506 }
507 } else {
508 // Truncate block and return a pointer to the following block
509 // Set used bit and length on new block
510 found_block->set_length(found_length - length);
511 found_block = following_block(found_block);
512
513 size_t beg = segment_for(found_block);
514 mark_segmap_as_used(beg, beg + length);
515 found_block->set_length(length);
516 }
517
518 found_block->set_used();
519 _freelist_segments -= length;
520 return found_block;
521 }
522
523 //----------------------------------------------------------------------------
524 // Non-product code
525
526 #ifndef PRODUCT
527
528 void CodeHeap::print() {
529 tty->print_cr("The Heap");
530 }
531
532 void CodeHeap::verify() {
533 if (VerifyCodeCache) {
534 size_t len = 0;
535 int count = 0;
536 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
537 len += b->length();
538 count++;
539 // Check if we have merged all free blocks
540 assert(merge_right(b) == false, "Missed merging opportunity");
541 }
542 // Verify that freelist contains the right amount of free space
543 assert(len == _freelist_segments, "wrong freelist");
544
545 for(HeapBlock* h = first_block(); h != NULL; h = next_block(h)) {
546 if (h->free()) count--;
547 }
548 // Verify that the freelist contains the same number of blocks
549 // than free blocks found on the full list.
550 assert(count == 0, "missing free blocks");
551
552 // Verify that the number of free blocks is not out of hand.
553 static int free_block_threshold = 10000;
554 if (count > free_block_threshold) {
555 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
556 // Double the warning limit
557 free_block_threshold *= 2;
558 }
559 }
560 }
561
562 #endif