1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)heap.cpp 1.55 07/10/04 10:49:31 JVM"
3 #endif
4 /*
5 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 # include "incls/_precompiled.incl"
29 # include "incls/_heap.cpp.incl"
30
31
32 size_t CodeHeap::header_size() {
33 return sizeof(HeapBlock);
34 }
35
36
37 // Implementation of Heap
38
39 CodeHeap::CodeHeap() {
40 _number_of_committed_segments = 0;
41 _number_of_reserved_segments = 0;
42 _segment_size = 0;
43 _log2_segment_size = 0;
44 _next_segment = 0;
45 _freelist = NULL;
46 _free_segments = 0;
47 }
48
49
50 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
51 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
52 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
53 // setup _segmap pointers for faster indexing
54 address p = (address)_segmap.low() + beg;
55 address q = (address)_segmap.low() + end;
56 // initialize interval
57 while (p < q) *p++ = 0xFF;
58 }
59
60
61 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
62 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
63 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
64 // setup _segmap pointers for faster indexing
65 address p = (address)_segmap.low() + beg;
66 address q = (address)_segmap.low() + end;
67 // initialize interval
68 int i = 0;
69 while (p < q) {
70 *p++ = i++;
71 if (i == 0xFF) i = 1;
72 }
73 }
74
75
76 static size_t align_to_page_size(size_t size) {
77 const size_t alignment = (size_t)os::vm_page_size();
78 assert(is_power_of_2(alignment), "no kidding ???");
79 return (size + alignment - 1) & ~(alignment - 1);
80 }
81
82
83 static size_t align_to_allocation_size(size_t size) {
84 const size_t alignment = (size_t)os::vm_allocation_granularity();
85 assert(is_power_of_2(alignment), "no kidding ???");
86 return (size + alignment - 1) & ~(alignment - 1);
87 }
88
89
90 void CodeHeap::on_code_mapping(char* base, size_t size) {
91 #ifdef LINUX
92 extern void linux_wrap_code(char* base, size_t size);
93 linux_wrap_code(base, size);
94 #endif
95 }
96
97
98 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
99 size_t segment_size) {
100 assert(reserved_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 const size_t page_size = os::can_execute_large_page_memory() ?
109 os::page_size_for_region(committed_size, reserved_size, 8) :
110 os::vm_page_size();
111 const size_t granularity = os::vm_allocation_granularity();
112 const size_t r_align = MAX2(page_size, granularity);
113 const size_t r_size = align_size_up(reserved_size, r_align);
114 const size_t c_size = align_size_up(committed_size, page_size);
115
116 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
117 MAX2(page_size, granularity);
118 ReservedSpace rs(r_size, rs_align, rs_align > 0);
119 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
120 rs.base(), rs.size());
121 if (!_memory.initialize(rs, c_size)) {
122 return false;
123 }
124
125 on_code_mapping(_memory.low(), _memory.committed_size());
126 _number_of_committed_segments = number_of_segments(_memory.committed_size());
127 _number_of_reserved_segments = number_of_segments(_memory.reserved_size());
128 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
129
130 // reserve space for _segmap
131 if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {
132 return false;
133 }
134 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
135 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
136 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
137
138 // initialize remaining instance variables
139 clear();
140 return true;
141 }
142
143
144 void CodeHeap::release() {
145 Unimplemented();
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 char* base = _memory.low() + _memory.committed_size();
154 if (!_memory.expand_by(dm)) return false;
155 on_code_mapping(base, dm);
156 size_t i = _number_of_committed_segments;
157 _number_of_committed_segments = number_of_segments(_memory.committed_size());
158 assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");
159 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
160 // expand _segmap space
161 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
162 if (ds > 0) {
163 if (!_segmap.expand_by(ds)) return false;
164 }
165 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
166 // initialize additional segmap entries
167 mark_segmap_as_free(i, _number_of_committed_segments);
168 }
169 return true;
170 }
171
172
173 void CodeHeap::shrink_by(size_t size) {
174 Unimplemented();
175 }
176
177
178 void CodeHeap::clear() {
179 _next_segment = 0;
180 mark_segmap_as_free(0, _number_of_committed_segments);
181 }
182
183
184 void* CodeHeap::allocate(size_t size) {
185 size_t length = number_of_segments(size + sizeof(HeapBlock));
186 assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");
187
188 // First check if we can satify request from freelist
189 debug_only(verify());
190 HeapBlock* block = search_freelist(length);
191 debug_only(if (VerifyCodeCacheOften) verify());
192 if (block != NULL) {
193 assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");
194 assert(!block->free(), "must be marked free");
195 #ifdef ASSERT
196 memset((void *)block->allocated_space(), badCodeHeapNewVal, size);
197 #endif
198 return block->allocated_space();
199 }
200
201 if (length < CodeCacheMinBlockLength) {
202 length = CodeCacheMinBlockLength;
203 }
204 if (_next_segment + length <= _number_of_committed_segments) {
205 mark_segmap_as_used(_next_segment, _next_segment + length);
206 HeapBlock* b = block_at(_next_segment);
207 b->initialize(length);
208 _next_segment += length;
209 #ifdef ASSERT
210 memset((void *)b->allocated_space(), badCodeHeapNewVal, size);
211 #endif
212 return b->allocated_space();
213 } else {
214 return NULL;
215 }
216 }
217
218
219 void CodeHeap::deallocate(void* p) {
220 assert(p == find_start(p), "illegal deallocation");
221 // Find start of HeapBlock
222 HeapBlock* b = (((HeapBlock *)p) - 1);
223 assert(b->allocated_space() == p, "sanity check");
224 #ifdef ASSERT
225 memset((void *)b->allocated_space(),
226 badCodeHeapFreeVal,
227 size(b->length()) - sizeof(HeapBlock));
228 #endif
229 add_to_freelist(b);
230
231 debug_only(if (VerifyCodeCacheOften) verify());
232 }
233
234
235 void* CodeHeap::find_start(void* p) const {
236 if (!contains(p)) {
237 return NULL;
238 }
239 size_t i = segment_for(p);
240 address b = (address)_segmap.low();
241 if (b[i] == 0xFF) {
242 return NULL;
243 }
244 while (b[i] > 0) i -= (int)b[i];
245 HeapBlock* h = block_at(i);
246 if (h->free()) {
247 return NULL;
248 }
249 return h->allocated_space();
250 }
251
252
253 size_t CodeHeap::alignment_unit() const {
254 // this will be a power of two
255 return _segment_size;
256 }
257
258
259 size_t CodeHeap::alignment_offset() const {
260 // The lowest address in any allocated block will be
261 // equal to alignment_offset (mod alignment_unit).
262 return sizeof(HeapBlock) & (_segment_size - 1);
263 }
264
265 // Finds the next free heapblock. If the current one is free, that it returned
266 void* CodeHeap::next_free(HeapBlock *b) const {
267 // Since free blocks are merged, there is max. on free block
268 // between two used ones
269 if (b != NULL && b->free()) b = next_block(b);
270 assert(b == NULL || !b->free(), "must be in use or at end of heap");
271 return (b == NULL) ? NULL : b->allocated_space();
272 }
273
274 // Returns the first used HeapBlock
275 HeapBlock* CodeHeap::first_block() const {
276 if (_next_segment > 0)
277 return block_at(0);
278 return NULL;
279 }
280
281 HeapBlock *CodeHeap::block_start(void *q) const {
282 HeapBlock* b = (HeapBlock*)find_start(q);
283 if (b == NULL) return NULL;
284 return b - 1;
285 }
286
287 // Returns the next Heap block an offset into one
288 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
289 if (b == NULL) return NULL;
290 size_t i = segment_for(b) + b->length();
291 if (i < _next_segment)
292 return block_at(i);
293 return NULL;
294 }
295
296
297 // Returns current capacity
298 size_t CodeHeap::capacity() const {
299 return _memory.committed_size();
300 }
301
302 size_t CodeHeap::max_capacity() const {
303 return _memory.reserved_size();
304 }
305
306 size_t CodeHeap::allocated_capacity() const {
307 // Start with the committed size in _memory;
308 size_t l = _memory.committed_size();
309
310 // Subtract the committed, but unused, segments
311 l -= size(_number_of_committed_segments - _next_segment);
312
313 // Subtract the size of the freelist
314 l -= size(_free_segments);
315
316 return l;
317 }
318
319 // Free list management
320
321 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
322 return (FreeBlock*)(((address)b) + _segment_size * b->length());
323 }
324
325 // Inserts block b after a
326 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
327 assert(a != NULL && b != NULL, "must be real pointers");
328
329 // Link b into the list after a
330 b->set_link(a->link());
331 a->set_link(b);
332
333 // See if we can merge blocks
334 merge_right(b); // Try to make b bigger
335 merge_right(a); // Try to make a include b
336 }
337
338 // Try to merge this block with the following block
339 void CodeHeap::merge_right(FreeBlock *a) {
340 assert(a->free(), "must be a free block");
341 if (following_block(a) == a->link()) {
342 assert(a->link() != NULL && a->link()->free(), "must be free too");
343 // Update block a to include the following block
344 a->set_length(a->length() + a->link()->length());
345 a->set_link(a->link()->link());
346 // Update find_start map
347 size_t beg = segment_for(a);
348 mark_segmap_as_used(beg, beg + a->length());
349 }
350 }
351
352 void CodeHeap::add_to_freelist(HeapBlock *a) {
353 FreeBlock* b = (FreeBlock*)a;
354 assert(b != _freelist, "cannot be removed twice");
355
356 // Mark as free and update free space count
357 _free_segments += b->length();
358 b->set_free();
359
360 // First element in list?
361 if (_freelist == NULL) {
362 _freelist = b;
363 b->set_link(NULL);
364 return;
365 }
366
367 // Scan for right place to put into list. List
368 // is sorted by increasing addresseses
369 FreeBlock* prev = NULL;
370 FreeBlock* cur = _freelist;
371 while(cur != NULL && cur < b) {
372 assert(prev == NULL || prev < cur, "must be ordered");
373 prev = cur;
374 cur = cur->link();
375 }
376
377 assert( (prev == NULL && b < _freelist) ||
378 (prev < b && (cur == NULL || b < cur)), "list must be ordered");
379
380 if (prev == NULL) {
381 // Insert first in list
382 b->set_link(_freelist);
383 _freelist = b;
384 merge_right(_freelist);
385 } else {
386 insert_after(prev, b);
387 }
388 }
389
390 // Search freelist for an entry on the list with the best fit
391 // Return NULL if no one was found
392 FreeBlock* CodeHeap::search_freelist(size_t length) {
393 FreeBlock *best_block = NULL;
394 FreeBlock *best_prev = NULL;
395 size_t best_length = 0;
396
397 // Search for smallest block which is bigger than length
398 FreeBlock *prev = NULL;
399 FreeBlock *cur = _freelist;
400 while(cur != NULL) {
401 size_t l = cur->length();
402 if (l >= length && (best_block == NULL || best_length > l)) {
403 // Remember best block, its previous element, and its length
404 best_block = cur;
405 best_prev = prev;
406 best_length = best_block->length();
407 }
408
409 // Next element in list
410 prev = cur;
411 cur = cur->link();
412 }
413
414 if (best_block == NULL) {
415 // None found
416 return NULL;
417 }
418
419 assert((best_prev == NULL && _freelist == best_block ) ||
420 (best_prev != NULL && best_prev->link() == best_block), "sanity check");
421
422 // Exact (or at least good enough) fit. Remove from list.
423 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
424 if (best_length < length + CodeCacheMinBlockLength) {
425 length = best_length;
426 if (best_prev == NULL) {
427 assert(_freelist == best_block, "sanity check");
428 _freelist = _freelist->link();
429 } else {
430 // Unmap element
431 best_prev->set_link(best_block->link());
432 }
433 } else {
434 // Truncate block and return a pointer to the following block
435 best_block->set_length(best_length - length);
436 best_block = following_block(best_block);
437 // Set used bit and length on new block
438 size_t beg = segment_for(best_block);
439 mark_segmap_as_used(beg, beg + length);
440 best_block->set_length(length);
441 }
442
443 best_block->set_used();
444 _free_segments -= length;
445 return best_block;
446 }
447
448 //----------------------------------------------------------------------------
449 // Non-product code
450
451 #ifndef PRODUCT
452
453 void CodeHeap::print() {
454 tty->print_cr("The Heap");
455 }
456
457 #endif
458
459 void CodeHeap::verify() {
460 // Count the number of blocks on the freelist, and the amount of space
461 // represented.
462 int count = 0;
463 size_t len = 0;
464 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
465 len += b->length();
466 count++;
467 }
468
469 // Verify that freelist contains the right amount of free space
470 guarantee(len == _free_segments, "wrong freelist");
471
472 // Verify that the number of free blocks is not out of hand.
473 static int free_block_threshold = 10000;
474 if (count > free_block_threshold) {
475 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
476 // Double the warning limit
477 free_block_threshold *= 2;
478 }
479
480 // Verify that the freelist contains the same number of free blocks that is
481 // found on the full list.
482 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
483 if (h->free()) count--;
484 }
485 guarantee(count == 0, "missing free blocks");
486 }
487