1 /*
2 * Copyright (c) 1997, 2010, 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
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 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
134 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
135 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
136
137 // initialize remaining instance variables
138 clear();
139 return true;
140 }
141
142
143 void CodeHeap::release() {
144 Unimplemented();
145 }
146
147
148 bool CodeHeap::expand_by(size_t size) {
149 // expand _memory space
150 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
151 if (dm > 0) {
152 char* base = _memory.low() + _memory.committed_size();
153 if (!_memory.expand_by(dm)) return false;
154 on_code_mapping(base, dm);
155 size_t i = _number_of_committed_segments;
156 _number_of_committed_segments = number_of_segments(_memory.committed_size());
157 assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");
158 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
159 // expand _segmap space
160 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
161 if (ds > 0) {
162 if (!_segmap.expand_by(ds)) return false;
163 }
164 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
165 // initialize additional segmap entries
166 mark_segmap_as_free(i, _number_of_committed_segments);
167 }
168 return true;
169 }
170
171
172 void CodeHeap::shrink_by(size_t size) {
173 Unimplemented();
174 }
175
176
177 void CodeHeap::clear() {
178 _next_segment = 0;
179 mark_segmap_as_free(0, _number_of_committed_segments);
180 }
181
182
183 void* CodeHeap::allocate(size_t size) {
184 size_t length = number_of_segments(size + sizeof(HeapBlock));
185 assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");
186
187 // First check if we can satify request from freelist
188 debug_only(verify());
189 HeapBlock* block = search_freelist(length);
190 debug_only(if (VerifyCodeCacheOften) verify());
191 if (block != NULL) {
192 assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");
193 assert(!block->free(), "must be marked free");
194 #ifdef ASSERT
195 memset((void *)block->allocated_space(), badCodeHeapNewVal, size);
196 #endif
197 return block->allocated_space();
198 }
199
200 if (length < CodeCacheMinBlockLength) {
201 length = CodeCacheMinBlockLength;
202 }
203 if (_next_segment + length <= _number_of_committed_segments) {
204 mark_segmap_as_used(_next_segment, _next_segment + length);
205 HeapBlock* b = block_at(_next_segment);
206 b->initialize(length);
207 _next_segment += length;
208 #ifdef ASSERT
209 memset((void *)b->allocated_space(), badCodeHeapNewVal, size);
210 #endif
211 return b->allocated_space();
212 } else {
213 return NULL;
214 }
215 }
216
217
218 void CodeHeap::deallocate(void* p) {
219 assert(p == find_start(p), "illegal deallocation");
220 // Find start of HeapBlock
221 HeapBlock* b = (((HeapBlock *)p) - 1);
222 assert(b->allocated_space() == p, "sanity check");
223 #ifdef ASSERT
224 memset((void *)b->allocated_space(),
225 badCodeHeapFreeVal,
226 size(b->length()) - sizeof(HeapBlock));
227 #endif
228 add_to_freelist(b);
229
230 debug_only(if (VerifyCodeCacheOften) verify());
231 }
232
233
234 void* CodeHeap::find_start(void* p) const {
235 if (!contains(p)) {
236 return NULL;
237 }
238 size_t i = segment_for(p);
239 address b = (address)_segmap.low();
240 if (b[i] == 0xFF) {
241 return NULL;
242 }
243 while (b[i] > 0) i -= (int)b[i];
244 HeapBlock* h = block_at(i);
245 if (h->free()) {
246 return NULL;
247 }
248 return h->allocated_space();
249 }
250
251
252 size_t CodeHeap::alignment_unit() const {
253 // this will be a power of two
254 return _segment_size;
255 }
256
257
258 size_t CodeHeap::alignment_offset() const {
259 // The lowest address in any allocated block will be
260 // equal to alignment_offset (mod alignment_unit).
261 return sizeof(HeapBlock) & (_segment_size - 1);
262 }
263
264 // Finds the next free heapblock. If the current one is free, that it returned
265 void* CodeHeap::next_free(HeapBlock *b) const {
266 // Since free blocks are merged, there is max. on free block
267 // between two used ones
268 if (b != NULL && b->free()) b = next_block(b);
269 assert(b == NULL || !b->free(), "must be in use or at end of heap");
270 return (b == NULL) ? NULL : b->allocated_space();
271 }
272
273 // Returns the first used HeapBlock
274 HeapBlock* CodeHeap::first_block() const {
275 if (_next_segment > 0)
276 return block_at(0);
277 return NULL;
278 }
279
280 HeapBlock *CodeHeap::block_start(void *q) const {
281 HeapBlock* b = (HeapBlock*)find_start(q);
282 if (b == NULL) return NULL;
283 return b - 1;
284 }
285
286 // Returns the next Heap block an offset into one
287 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
288 if (b == NULL) return NULL;
289 size_t i = segment_for(b) + b->length();
290 if (i < _next_segment)
291 return block_at(i);
292 return NULL;
293 }
294
295
296 // Returns current capacity
297 size_t CodeHeap::capacity() const {
298 return _memory.committed_size();
299 }
300
301 size_t CodeHeap::max_capacity() const {
302 return _memory.reserved_size();
303 }
304
305 size_t CodeHeap::allocated_capacity() const {
306 // Start with the committed size in _memory;
307 size_t l = _memory.committed_size();
308
309 // Subtract the committed, but unused, segments
310 l -= size(_number_of_committed_segments - _next_segment);
311
312 // Subtract the size of the freelist
313 l -= size(_free_segments);
314
315 return l;
316 }
317
318 size_t CodeHeap::largest_free_block() const {
319 size_t len = 0;
320 for (FreeBlock* b = _freelist; b != NULL; b = b->link()) {
321 if (b->length() > len)
322 len = b->length();
323 }
324 return size(len);
325 }
326
327 // Free list management
328
329 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
330 return (FreeBlock*)(((address)b) + _segment_size * b->length());
331 }
332
333 // Inserts block b after a
334 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
335 assert(a != NULL && b != NULL, "must be real pointers");
336
337 // Link b into the list after a
338 b->set_link(a->link());
339 a->set_link(b);
340
341 // See if we can merge blocks
342 merge_right(b); // Try to make b bigger
343 merge_right(a); // Try to make a include b
344 }
345
346 // Try to merge this block with the following block
347 void CodeHeap::merge_right(FreeBlock *a) {
348 assert(a->free(), "must be a free block");
349 if (following_block(a) == a->link()) {
350 assert(a->link() != NULL && a->link()->free(), "must be free too");
351 // Update block a to include the following block
352 a->set_length(a->length() + a->link()->length());
353 a->set_link(a->link()->link());
354 // Update find_start map
355 size_t beg = segment_for(a);
356 mark_segmap_as_used(beg, beg + a->length());
357 }
358 }
359
360 void CodeHeap::add_to_freelist(HeapBlock *a) {
361 FreeBlock* b = (FreeBlock*)a;
362 assert(b != _freelist, "cannot be removed twice");
363
364 // Mark as free and update free space count
365 _free_segments += b->length();
366 b->set_free();
367
368 // First element in list?
369 if (_freelist == NULL) {
370 _freelist = b;
371 b->set_link(NULL);
372 return;
373 }
374
375 // Scan for right place to put into list. List
376 // is sorted by increasing addresseses
377 FreeBlock* prev = NULL;
378 FreeBlock* cur = _freelist;
379 while(cur != NULL && cur < b) {
380 assert(prev == NULL || prev < cur, "must be ordered");
381 prev = cur;
382 cur = cur->link();
383 }
384
385 assert( (prev == NULL && b < _freelist) ||
386 (prev < b && (cur == NULL || b < cur)), "list must be ordered");
387
388 if (prev == NULL) {
389 // Insert first in list
390 b->set_link(_freelist);
391 _freelist = b;
392 merge_right(_freelist);
393 } else {
394 insert_after(prev, b);
395 }
396 }
397
398 // Search freelist for an entry on the list with the best fit
399 // Return NULL if no one was found
400 FreeBlock* CodeHeap::search_freelist(size_t length) {
401 FreeBlock *best_block = NULL;
402 FreeBlock *best_prev = NULL;
403 size_t best_length = 0;
404
405 // Search for smallest block which is bigger than length
406 FreeBlock *prev = NULL;
407 FreeBlock *cur = _freelist;
408 while(cur != NULL) {
409 size_t l = cur->length();
410 if (l >= length && (best_block == NULL || best_length > l)) {
411 // Remember best block, its previous element, and its length
412 best_block = cur;
413 best_prev = prev;
414 best_length = best_block->length();
415 }
416
417 // Next element in list
418 prev = cur;
419 cur = cur->link();
420 }
421
422 if (best_block == NULL) {
423 // None found
424 return NULL;
425 }
426
427 assert((best_prev == NULL && _freelist == best_block ) ||
428 (best_prev != NULL && best_prev->link() == best_block), "sanity check");
429
430 // Exact (or at least good enough) fit. Remove from list.
431 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
432 if (best_length < length + CodeCacheMinBlockLength) {
433 length = best_length;
434 if (best_prev == NULL) {
435 assert(_freelist == best_block, "sanity check");
436 _freelist = _freelist->link();
437 } else {
438 // Unmap element
439 best_prev->set_link(best_block->link());
440 }
441 } else {
442 // Truncate block and return a pointer to the following block
443 best_block->set_length(best_length - length);
444 best_block = following_block(best_block);
445 // Set used bit and length on new block
446 size_t beg = segment_for(best_block);
447 mark_segmap_as_used(beg, beg + length);
448 best_block->set_length(length);
449 }
450
451 best_block->set_used();
452 _free_segments -= length;
453 return best_block;
454 }
455
456 //----------------------------------------------------------------------------
457 // Non-product code
458
459 #ifndef PRODUCT
460
461 void CodeHeap::print() {
462 tty->print_cr("The Heap");
463 }
464
465 #endif
466
467 void CodeHeap::verify() {
468 // Count the number of blocks on the freelist, and the amount of space
469 // represented.
470 int count = 0;
471 size_t len = 0;
472 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
473 len += b->length();
474 count++;
475 }
476
477 // Verify that freelist contains the right amount of free space
478 // guarantee(len == _free_segments, "wrong freelist");
479
480 // Verify that the number of free blocks is not out of hand.
481 static int free_block_threshold = 10000;
482 if (count > free_block_threshold) {
483 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
484 // Double the warning limit
485 free_block_threshold *= 2;
486 }
487
488 // Verify that the freelist contains the same number of free blocks that is
489 // found on the full list.
490 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
491 if (h->free()) count--;
492 }
493 // guarantee(count == 0, "missing free blocks");
494 }