1 /*
2 * Copyright (c) 2001, 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 "gc_implementation/shared/adaptiveSizePolicy.hpp"
27 #include "gc_implementation/shared/gcPolicyCounters.hpp"
28 #include "gc_implementation/shared/vmGCOperations.hpp"
29 #include "memory/cardTableRS.hpp"
30 #include "memory/collectorPolicy.hpp"
31 #include "memory/gcLocker.inline.hpp"
32 #include "memory/genCollectedHeap.hpp"
33 #include "memory/generationSpec.hpp"
34 #include "memory/space.hpp"
35 #include "memory/universe.hpp"
36 #include "runtime/arguments.hpp"
37 #include "runtime/globals_extension.hpp"
38 #include "runtime/handles.inline.hpp"
39 #include "runtime/java.hpp"
40 #include "runtime/thread.inline.hpp"
41 #include "runtime/vmThread.hpp"
42 #include "utilities/macros.hpp"
43 #if INCLUDE_ALL_GCS
44 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"
45 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"
46 #endif // INCLUDE_ALL_GCS
47
48 // CollectorPolicy methods
49
50 CollectorPolicy::CollectorPolicy() :
51 _space_alignment(0),
52 _heap_alignment(0),
53 _initial_heap_byte_size(InitialHeapSize),
54 _max_heap_byte_size(MaxHeapSize),
55 _min_heap_byte_size(Arguments::min_heap_size()),
56 _max_heap_size_cmdline(false),
57 _size_policy(NULL),
58 _should_clear_all_soft_refs(false),
59 _all_soft_refs_clear(false)
60 {}
61
62 #ifdef ASSERT
63 void CollectorPolicy::assert_flags() {
64 assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
65 assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
66 assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
67 }
68
69 void CollectorPolicy::assert_size_info() {
70 assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
71 assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
72 assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
73 assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
74 assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
75 assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
76 assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
77 assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
78 }
79 #endif // ASSERT
80
81 void CollectorPolicy::initialize_flags() {
82 assert(_space_alignment != 0, "Space alignment not set up properly");
83 assert(_heap_alignment != 0, "Heap alignment not set up properly");
84 assert(_heap_alignment >= _space_alignment,
85 err_msg("heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
86 _heap_alignment, _space_alignment));
87 assert(_heap_alignment % _space_alignment == 0,
88 err_msg("heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
89 _heap_alignment, _space_alignment));
90
91 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
92 if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
93 vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
94 }
95 if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
96 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
97 }
98 _max_heap_size_cmdline = true;
99 }
100
101 // Check heap parameter properties
102 if (InitialHeapSize < M) {
103 vm_exit_during_initialization("Too small initial heap");
104 }
105 if (_min_heap_byte_size < M) {
106 vm_exit_during_initialization("Too small minimum heap");
107 }
108
109 // User inputs from -Xmx and -Xms must be aligned
110 _min_heap_byte_size = align_size_up(_min_heap_byte_size, _heap_alignment);
111 uintx aligned_initial_heap_size = align_size_up(InitialHeapSize, _heap_alignment);
112 uintx aligned_max_heap_size = align_size_up(MaxHeapSize, _heap_alignment);
113
114 // Write back to flags if the values changed
115 if (aligned_initial_heap_size != InitialHeapSize) {
116 FLAG_SET_ERGO(uintx, InitialHeapSize, aligned_initial_heap_size);
117 }
118 if (aligned_max_heap_size != MaxHeapSize) {
119 FLAG_SET_ERGO(uintx, MaxHeapSize, aligned_max_heap_size);
120 }
121
122 if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
123 InitialHeapSize < _min_heap_byte_size) {
124 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
125 }
126 if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
127 FLAG_SET_ERGO(uintx, MaxHeapSize, InitialHeapSize);
128 } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
129 FLAG_SET_ERGO(uintx, InitialHeapSize, MaxHeapSize);
130 if (InitialHeapSize < _min_heap_byte_size) {
131 _min_heap_byte_size = InitialHeapSize;
132 }
133 }
134
135 _initial_heap_byte_size = InitialHeapSize;
136 _max_heap_byte_size = MaxHeapSize;
137
138 FLAG_SET_ERGO(uintx, MinHeapDeltaBytes, align_size_up(MinHeapDeltaBytes, _space_alignment));
139
140 DEBUG_ONLY(CollectorPolicy::assert_flags();)
141 }
142
143 void CollectorPolicy::initialize_size_info() {
144 if (PrintGCDetails && Verbose) {
145 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap "
146 SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
147 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
148 }
149
150 DEBUG_ONLY(CollectorPolicy::assert_size_info();)
151 }
152
153 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
154 bool result = _should_clear_all_soft_refs;
155 set_should_clear_all_soft_refs(false);
156 return result;
157 }
158
159 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
160 int max_covered_regions) {
161 return new CardTableRS(whole_heap, max_covered_regions);
162 }
163
164 void CollectorPolicy::cleared_all_soft_refs() {
165 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
166 // have been cleared in the last collection but if the gc overhear
167 // limit continues to be near, SoftRefs should still be cleared.
168 if (size_policy() != NULL) {
169 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
170 }
171 _all_soft_refs_clear = true;
172 }
173
174 size_t CollectorPolicy::compute_heap_alignment() {
175 // The card marking array and the offset arrays for old generations are
176 // committed in os pages as well. Make sure they are entirely full (to
177 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
178 // byte entry and the os page size is 4096, the maximum heap size should
179 // be 512*4096 = 2MB aligned.
180
181 size_t alignment = GenRemSet::max_alignment_constraint();
182
183 // Parallel GC does its own alignment of the generations to avoid requiring a
184 // large page (256M on some platforms) for the permanent generation. The
185 // other collectors should also be updated to do their own alignment and then
186 // this use of lcm() should be removed.
187 if (UseLargePages && !UseParallelGC) {
188 // In presence of large pages we have to make sure that our
189 // alignment is large page aware
190 alignment = lcm(os::large_page_size(), alignment);
191 }
192
193 return alignment;
194 }
195
196 // GenCollectorPolicy methods
197
198 GenCollectorPolicy::GenCollectorPolicy() :
199 _min_gen0_size(0),
200 _initial_gen0_size(0),
201 _max_gen0_size(0),
202 _gen_alignment(0),
203 _generations(NULL)
204 {}
205
206 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
207 return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
208 }
209
210 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
211 size_t maximum_size) {
212 size_t max_minus = maximum_size - _gen_alignment;
213 return desired_size < max_minus ? desired_size : max_minus;
214 }
215
216
217 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
218 size_t init_promo_size,
219 size_t init_survivor_size) {
220 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
221 _size_policy = new AdaptiveSizePolicy(init_eden_size,
222 init_promo_size,
223 init_survivor_size,
224 max_gc_pause_sec,
225 GCTimeRatio);
226 }
227
228 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
229 // The young generation must be aligned and have room for eden + two survivors
230 return align_size_up(3 * _space_alignment, _gen_alignment);
231 }
232
233 #ifdef ASSERT
234 void GenCollectorPolicy::assert_flags() {
235 CollectorPolicy::assert_flags();
236 assert(NewSize >= _min_gen0_size, "Ergonomics decided on a too small young gen size");
237 assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
238 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
239 assert(NewSize % _gen_alignment == 0, "NewSize alignment");
240 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
241 }
242
243 void TwoGenerationCollectorPolicy::assert_flags() {
244 GenCollectorPolicy::assert_flags();
245 assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
246 assert(OldSize % _gen_alignment == 0, "OldSize alignment");
247 }
248
249 void GenCollectorPolicy::assert_size_info() {
250 CollectorPolicy::assert_size_info();
251 // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
252 assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
253 assert(NewSize == _initial_gen0_size, "Discrepancy between NewSize flag and local storage");
254 assert(MaxNewSize == _max_gen0_size, "Discrepancy between MaxNewSize flag and local storage");
255 assert(_min_gen0_size <= _initial_gen0_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
256 assert(_initial_gen0_size <= _max_gen0_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
257 assert(_min_gen0_size % _gen_alignment == 0, "_min_gen0_size alignment");
258 assert(_initial_gen0_size % _gen_alignment == 0, "_initial_gen0_size alignment");
259 assert(_max_gen0_size % _gen_alignment == 0, "_max_gen0_size alignment");
260 }
261
262 void TwoGenerationCollectorPolicy::assert_size_info() {
263 GenCollectorPolicy::assert_size_info();
264 assert(OldSize == _initial_gen1_size, "Discrepancy between OldSize flag and local storage");
265 assert(_min_gen1_size <= _initial_gen1_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
266 assert(_initial_gen1_size <= _max_gen1_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
267 assert(_max_gen1_size % _gen_alignment == 0, "_max_gen1_size alignment");
268 assert(_initial_gen1_size % _gen_alignment == 0, "_initial_gen1_size alignment");
269 assert(_max_heap_byte_size <= (_max_gen0_size + _max_gen1_size), "Total maximum heap sizes must be sum of generation maximum sizes");
270 }
271 #endif // ASSERT
272
273 void GenCollectorPolicy::initialize_flags() {
274 CollectorPolicy::initialize_flags();
275
276 assert(_gen_alignment != 0, "Generation alignment not set up properly");
277 assert(_heap_alignment >= _gen_alignment,
278 err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
279 _heap_alignment, _gen_alignment));
280 assert(_gen_alignment % _space_alignment == 0,
281 err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
282 _gen_alignment, _space_alignment));
283 assert(_heap_alignment % _gen_alignment == 0,
284 err_msg("heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
285 _heap_alignment, _gen_alignment));
286
287 // All generational heaps have a youngest gen; handle those flags here
288
289 // Make sure the heap is large enough for two generations
290 uintx smallest_new_size = young_gen_size_lower_bound();
291 uintx smallest_heap_size = align_size_up(smallest_new_size + align_size_up(_space_alignment, _gen_alignment),
292 _heap_alignment);
293 if (MaxHeapSize < smallest_heap_size) {
294 FLAG_SET_ERGO(uintx, MaxHeapSize, smallest_heap_size);
295 _max_heap_byte_size = MaxHeapSize;
296 }
297 // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
298 if (_min_heap_byte_size < smallest_heap_size) {
299 _min_heap_byte_size = smallest_heap_size;
300 if (InitialHeapSize < _min_heap_byte_size) {
301 FLAG_SET_ERGO(uintx, InitialHeapSize, smallest_heap_size);
302 _initial_heap_byte_size = smallest_heap_size;
303 }
304 }
305
306 // Now take the actual NewSize into account. We will silently increase NewSize
307 // if the user specified a smaller value.
308 smallest_new_size = MAX2(smallest_new_size, (uintx)align_size_down(NewSize, _gen_alignment));
309 if (smallest_new_size != NewSize) {
310 FLAG_SET_ERGO(uintx, NewSize, smallest_new_size);
311 }
312 _initial_gen0_size = NewSize;
313
314 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
315 uintx min_new_size = MAX2(_gen_alignment, _min_gen0_size);
316
317 if (MaxNewSize >= MaxHeapSize) {
318 // Make sure there is room for an old generation
319 uintx smaller_max_new_size = MaxHeapSize - _gen_alignment;
320 if (FLAG_IS_CMDLINE(MaxNewSize)) {
321 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
322 "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.",
323 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
324 }
325 FLAG_SET_ERGO(uintx, MaxNewSize, smaller_max_new_size);
326 if (NewSize > MaxNewSize) {
327 FLAG_SET_ERGO(uintx, NewSize, MaxNewSize);
328 _initial_gen0_size = NewSize;
329 }
330 } else if (MaxNewSize < min_new_size) {
331 FLAG_SET_ERGO(uintx, MaxNewSize, min_new_size);
332 } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) {
333 FLAG_SET_ERGO(uintx, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment));
334 }
335 _max_gen0_size = MaxNewSize;
336 }
337
338 if (NewSize > MaxNewSize) {
339 // At this point this should only happen if the user specifies a large NewSize and/or
340 // a small (but not too small) MaxNewSize.
341 if (FLAG_IS_CMDLINE(MaxNewSize)) {
342 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
343 "A new max generation size of " SIZE_FORMAT "k will be used.",
344 NewSize/K, MaxNewSize/K, NewSize/K);
345 }
346 FLAG_SET_ERGO(uintx, MaxNewSize, NewSize);
347 _max_gen0_size = MaxNewSize;
348 }
349
350 if (SurvivorRatio < 1 || NewRatio < 1) {
351 vm_exit_during_initialization("Invalid young gen ratio specified");
352 }
353
354 DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
355 }
356
357 void TwoGenerationCollectorPolicy::initialize_flags() {
358 GenCollectorPolicy::initialize_flags();
359
360 if (!is_size_aligned(OldSize, _gen_alignment)) {
361 FLAG_SET_ERGO(uintx, OldSize, align_size_down(OldSize, _gen_alignment));
362 }
363
364 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
365 // NewRatio will be used later to set the young generation size so we use
366 // it to calculate how big the heap should be based on the requested OldSize
367 // and NewRatio.
368 assert(NewRatio > 0, "NewRatio should have been set up earlier");
369 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
370
371 calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment);
372 FLAG_SET_ERGO(uintx, MaxHeapSize, calculated_heapsize);
373 _max_heap_byte_size = MaxHeapSize;
374 FLAG_SET_ERGO(uintx, InitialHeapSize, calculated_heapsize);
375 _initial_heap_byte_size = InitialHeapSize;
376 }
377
378 // Adjust NewSize and OldSize or MaxHeapSize to match each other
379 if (NewSize + OldSize > MaxHeapSize) {
380 if (_max_heap_size_cmdline) {
381 // Somebody has set a maximum heap size with the intention that we should not
382 // exceed it. Adjust New/OldSize as necessary.
383 uintx calculated_size = NewSize + OldSize;
384 double shrink_factor = (double) MaxHeapSize / calculated_size;
385 uintx smaller_new_size = align_size_down((uintx)(NewSize * shrink_factor), _gen_alignment);
386 FLAG_SET_ERGO(uintx, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
387 _initial_gen0_size = NewSize;
388
389 // OldSize is already aligned because above we aligned MaxHeapSize to
390 // _heap_alignment, and we just made sure that NewSize is aligned to
391 // _gen_alignment. In initialize_flags() we verified that _heap_alignment
392 // is a multiple of _gen_alignment.
393 FLAG_SET_ERGO(uintx, OldSize, MaxHeapSize - NewSize);
394 } else {
395 FLAG_SET_ERGO(uintx, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment));
396 _max_heap_byte_size = MaxHeapSize;
397 }
398 }
399
400 always_do_update_barrier = UseConcMarkSweepGC;
401
402 DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_flags();)
403 }
404
405 // Values set on the command line win over any ergonomically
406 // set command line parameters.
407 // Ergonomic choice of parameters are done before this
408 // method is called. Values for command line parameters such as NewSize
409 // and MaxNewSize feed those ergonomic choices into this method.
410 // This method makes the final generation sizings consistent with
411 // themselves and with overall heap sizings.
412 // In the absence of explicitly set command line flags, policies
413 // such as the use of NewRatio are used to size the generation.
414 void GenCollectorPolicy::initialize_size_info() {
415 CollectorPolicy::initialize_size_info();
416
417 // _space_alignment is used for alignment within a generation.
418 // There is additional alignment done down stream for some
419 // collectors that sometimes causes unwanted rounding up of
420 // generations sizes.
421
422 // Determine maximum size of gen0
423
424 size_t max_new_size = 0;
425 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
426 max_new_size = MaxNewSize;
427 } else {
428 max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
429 // Bound the maximum size by NewSize below (since it historically
430 // would have been NewSize and because the NewRatio calculation could
431 // yield a size that is too small) and bound it by MaxNewSize above.
432 // Ergonomics plays here by previously calculating the desired
433 // NewSize and MaxNewSize.
434 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
435 }
436 assert(max_new_size > 0, "All paths should set max_new_size");
437
438 // Given the maximum gen0 size, determine the initial and
439 // minimum gen0 sizes.
440
441 if (_max_heap_byte_size == _min_heap_byte_size) {
442 // The maximum and minimum heap sizes are the same so the generations
443 // minimum and initial must be the same as its maximum.
444 _min_gen0_size = max_new_size;
445 _initial_gen0_size = max_new_size;
446 _max_gen0_size = max_new_size;
447 } else {
448 size_t desired_new_size = 0;
449 if (!FLAG_IS_DEFAULT(NewSize)) {
450 // If NewSize is set ergonomically (for example by cms), it
451 // would make sense to use it. If it is used, also use it
452 // to set the initial size. Although there is no reason
453 // the minimum size and the initial size have to be the same,
454 // the current implementation gets into trouble during the calculation
455 // of the tenured generation sizes if they are different.
456 // Note that this makes the initial size and the minimum size
457 // generally small compared to the NewRatio calculation.
458 _min_gen0_size = NewSize;
459 desired_new_size = NewSize;
460 max_new_size = MAX2(max_new_size, NewSize);
461 } else {
462 // For the case where NewSize is the default, use NewRatio
463 // to size the minimum and initial generation sizes.
464 // Use the default NewSize as the floor for these values. If
465 // NewRatio is overly large, the resulting sizes can be too small.
466 _min_gen0_size = MAX2(scale_by_NewRatio_aligned(_min_heap_byte_size), NewSize);
467 desired_new_size =
468 MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize);
469 }
470
471 assert(_min_gen0_size > 0, "Sanity check");
472 _initial_gen0_size = desired_new_size;
473 _max_gen0_size = max_new_size;
474
475 // At this point the desirable initial and minimum sizes have been
476 // determined without regard to the maximum sizes.
477
478 // Bound the sizes by the corresponding overall heap sizes.
479 _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size);
480 _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size);
481 _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size);
482
483 // At this point all three sizes have been checked against the
484 // maximum sizes but have not been checked for consistency among the three.
485
486 // Final check min <= initial <= max
487 _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size);
488 _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size);
489 _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size);
490 }
491
492 // Write back to flags if necessary.
493 if (NewSize != _initial_gen0_size) {
494 FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);
495 }
496
497 if (MaxNewSize != _max_gen0_size) {
498 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
499 }
500
501 if (PrintGCDetails && Verbose) {
502 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
503 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
504 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
505 }
506
507 DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
508 }
509
510 // Call this method during the sizing of the gen1 to make
511 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has
512 // the most freedom in sizing because it is done before the
513 // policy for gen1 is applied. Once gen1 policies have been applied,
514 // there may be conflicts in the shape of the heap and this method
515 // is used to make the needed adjustments. The application of the
516 // policies could be more sophisticated (iterative for example) but
517 // keeping it simple also seems a worthwhile goal.
518 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
519 size_t* gen1_size_ptr,
520 const size_t heap_size) {
521 bool result = false;
522
523 if ((*gen0_size_ptr + *gen1_size_ptr) > heap_size) {
524 uintx smallest_new_size = young_gen_size_lower_bound();
525 if ((heap_size < (*gen0_size_ptr + _min_gen1_size)) &&
526 (heap_size >= _min_gen1_size + smallest_new_size)) {
527 // Adjust gen0 down to accommodate _min_gen1_size
528 *gen0_size_ptr = align_size_down_bounded(heap_size - _min_gen1_size, _gen_alignment);
529 result = true;
530 } else {
531 *gen1_size_ptr = align_size_down_bounded(heap_size - *gen0_size_ptr, _gen_alignment);
532 }
533 }
534 return result;
535 }
536
537 // Minimum sizes of the generations may be different than
538 // the initial sizes. An inconsistency is permitted here
539 // in the total size that can be specified explicitly by
540 // command line specification of OldSize and NewSize and
541 // also a command line specification of -Xms. Issue a warning
542 // but allow the values to pass.
543
544 void TwoGenerationCollectorPolicy::initialize_size_info() {
545 GenCollectorPolicy::initialize_size_info();
546
547 // At this point the minimum, initial and maximum sizes
548 // of the overall heap and of gen0 have been determined.
549 // The maximum gen1 size can be determined from the maximum gen0
550 // and maximum heap size since no explicit flags exist
551 // for setting the gen1 maximum.
552 _max_gen1_size = MAX2(_max_heap_byte_size - _max_gen0_size, _gen_alignment);
553
554 // If no explicit command line flag has been set for the
555 // gen1 size, use what is left for gen1
556 if (!FLAG_IS_CMDLINE(OldSize)) {
557 // The user has not specified any value but the ergonomics
558 // may have chosen a value (which may or may not be consistent
559 // with the overall heap size). In either case make
560 // the minimum, maximum and initial sizes consistent
561 // with the gen0 sizes and the overall heap sizes.
562 _min_gen1_size = MAX2(_min_heap_byte_size - _min_gen0_size, _gen_alignment);
563 _initial_gen1_size = MAX2(_initial_heap_byte_size - _initial_gen0_size, _gen_alignment);
564 // _max_gen1_size has already been made consistent above
565 FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);
566 } else {
567 // OldSize has been explicitly set on the command line. Use the
568 // OldSize and then determine the consequences.
569 _min_gen1_size = MIN2(OldSize, _min_heap_byte_size - _min_gen0_size);
570 _initial_gen1_size = OldSize;
571
572 // If the user has explicitly set an OldSize that is inconsistent
573 // with other command line flags, issue a warning.
574 // The generation minimums and the overall heap minimum should
575 // be within one generation alignment.
576 if ((_min_gen1_size + _min_gen0_size + _gen_alignment) < _min_heap_byte_size) {
577 warning("Inconsistency between minimum heap size and minimum "
578 "generation sizes: using minimum heap = " SIZE_FORMAT,
579 _min_heap_byte_size);
580 }
581 if (OldSize > _max_gen1_size) {
582 warning("Inconsistency between maximum heap size and maximum "
583 "generation sizes: using maximum heap = " SIZE_FORMAT
584 " -XX:OldSize flag is being ignored",
585 _max_heap_byte_size);
586 }
587 // If there is an inconsistency between the OldSize and the minimum and/or
588 // initial size of gen0, since OldSize was explicitly set, OldSize wins.
589 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size, _min_heap_byte_size)) {
590 if (PrintGCDetails && Verbose) {
591 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
592 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
593 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
594 }
595 }
596 // The same as above for the old gen initial size.
597 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
598 _initial_heap_byte_size)) {
599 if (PrintGCDetails && Verbose) {
600 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
601 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
602 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
603 }
604 }
605 }
606
607 _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size);
608
609 // Make sure that min gen1 <= initial gen1 <= max gen1.
610 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size);
611 _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size);
612
613 // Write back to flags if necessary
614 if (NewSize != _initial_gen0_size) {
615 FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);
616 }
617
618 if (MaxNewSize != _max_gen0_size) {
619 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
620 }
621
622 if (OldSize != _initial_gen1_size) {
623 FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);
624 }
625
626 if (PrintGCDetails && Verbose) {
627 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 "
628 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT,
629 _min_gen1_size, _initial_gen1_size, _max_gen1_size);
630 }
631
632 DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_size_info();)
633 }
634
635 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
636 bool is_tlab,
637 bool* gc_overhead_limit_was_exceeded) {
638 GenCollectedHeap *gch = GenCollectedHeap::heap();
639
640 debug_only(gch->check_for_valid_allocation_state());
641 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
642
643 // In general gc_overhead_limit_was_exceeded should be false so
644 // set it so here and reset it to true only if the gc time
645 // limit is being exceeded as checked below.
646 *gc_overhead_limit_was_exceeded = false;
647
648 HeapWord* result = NULL;
649
650 // Loop until the allocation is satisfied, or unsatisfied after GC.
651 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
652 HandleMark hm; // Discard any handles allocated in each iteration.
653
654 // First allocation attempt is lock-free.
655 Generation *gen0 = gch->get_gen(0);
656 assert(gen0->supports_inline_contig_alloc(),
657 "Otherwise, must do alloc within heap lock");
658 if (gen0->should_allocate(size, is_tlab)) {
659 result = gen0->par_allocate(size, is_tlab);
660 if (result != NULL) {
661 assert(gch->is_in_reserved(result), "result not in heap");
662 return result;
663 }
664 }
665 unsigned int gc_count_before; // Read inside the Heap_lock locked region.
666 {
667 MutexLocker ml(Heap_lock);
668 if (PrintGC && Verbose) {
669 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
670 " attempting locked slow path allocation");
671 }
672 // Note that only large objects get a shot at being
673 // allocated in later generations.
674 bool first_only = ! should_try_older_generation_allocation(size);
675
676 result = gch->attempt_allocation(size, is_tlab, first_only);
677 if (result != NULL) {
678 assert(gch->is_in_reserved(result), "result not in heap");
679 return result;
680 }
681
682 if (GC_locker::is_active_and_needs_gc()) {
683 if (is_tlab) {
684 return NULL; // Caller will retry allocating individual object.
685 }
686 if (!gch->is_maximal_no_gc()) {
687 // Try and expand heap to satisfy request.
688 result = expand_heap_and_allocate(size, is_tlab);
689 // Result could be null if we are out of space.
690 if (result != NULL) {
691 return result;
692 }
693 }
694
695 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
696 return NULL; // We didn't get to do a GC and we didn't get any memory.
697 }
698
699 // If this thread is not in a jni critical section, we stall
700 // the requestor until the critical section has cleared and
701 // GC allowed. When the critical section clears, a GC is
702 // initiated by the last thread exiting the critical section; so
703 // we retry the allocation sequence from the beginning of the loop,
704 // rather than causing more, now probably unnecessary, GC attempts.
705 JavaThread* jthr = JavaThread::current();
706 if (!jthr->in_critical()) {
707 MutexUnlocker mul(Heap_lock);
708 // Wait for JNI critical section to be exited
709 GC_locker::stall_until_clear();
710 gclocker_stalled_count += 1;
711 continue;
712 } else {
713 if (CheckJNICalls) {
714 fatal("Possible deadlock due to allocating while"
715 " in jni critical section");
716 }
717 return NULL;
718 }
719 }
720
721 // Read the gc count while the heap lock is held.
722 gc_count_before = Universe::heap()->total_collections();
723 }
724
725 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
726 VMThread::execute(&op);
727 if (op.prologue_succeeded()) {
728 result = op.result();
729 if (op.gc_locked()) {
730 assert(result == NULL, "must be NULL if gc_locked() is true");
731 continue; // Retry and/or stall as necessary.
732 }
733
734 // Allocation has failed and a collection
735 // has been done. If the gc time limit was exceeded the
736 // this time, return NULL so that an out-of-memory
737 // will be thrown. Clear gc_overhead_limit_exceeded
738 // so that the overhead exceeded does not persist.
739
740 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
741 const bool softrefs_clear = all_soft_refs_clear();
742
743 if (limit_exceeded && softrefs_clear) {
744 *gc_overhead_limit_was_exceeded = true;
745 size_policy()->set_gc_overhead_limit_exceeded(false);
746 if (op.result() != NULL) {
747 CollectedHeap::fill_with_object(op.result(), size);
748 }
749 return NULL;
750 }
751 assert(result == NULL || gch->is_in_reserved(result),
752 "result not in heap");
753 return result;
754 }
755
756 // Give a warning if we seem to be looping forever.
757 if ((QueuedAllocationWarningCount > 0) &&
758 (try_count % QueuedAllocationWarningCount == 0)) {
759 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
760 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
761 }
762 }
763 }
764
765 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
766 bool is_tlab) {
767 GenCollectedHeap *gch = GenCollectedHeap::heap();
768 HeapWord* result = NULL;
769 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
770 Generation *gen = gch->get_gen(i);
771 if (gen->should_allocate(size, is_tlab)) {
772 result = gen->expand_and_allocate(size, is_tlab);
773 }
774 }
775 assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
776 return result;
777 }
778
779 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
780 bool is_tlab) {
781 GenCollectedHeap *gch = GenCollectedHeap::heap();
782 GCCauseSetter x(gch, GCCause::_allocation_failure);
783 HeapWord* result = NULL;
784
785 assert(size != 0, "Precondition violated");
786 if (GC_locker::is_active_and_needs_gc()) {
787 // GC locker is active; instead of a collection we will attempt
788 // to expand the heap, if there's room for expansion.
789 if (!gch->is_maximal_no_gc()) {
790 result = expand_heap_and_allocate(size, is_tlab);
791 }
792 return result; // Could be null if we are out of space.
793 } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
794 // Do an incremental collection.
795 gch->do_collection(false /* full */,
796 false /* clear_all_soft_refs */,
797 size /* size */,
798 is_tlab /* is_tlab */,
799 number_of_generations() - 1 /* max_level */);
800 } else {
801 if (Verbose && PrintGCDetails) {
802 gclog_or_tty->print(" :: Trying full because partial may fail :: ");
803 }
804 // Try a full collection; see delta for bug id 6266275
805 // for the original code and why this has been simplified
806 // with from-space allocation criteria modified and
807 // such allocation moved out of the safepoint path.
808 gch->do_collection(true /* full */,
809 false /* clear_all_soft_refs */,
810 size /* size */,
811 is_tlab /* is_tlab */,
812 number_of_generations() - 1 /* max_level */);
813 }
814
815 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
816
817 if (result != NULL) {
818 assert(gch->is_in_reserved(result), "result not in heap");
819 return result;
820 }
821
822 // OK, collection failed, try expansion.
823 result = expand_heap_and_allocate(size, is_tlab);
824 if (result != NULL) {
825 return result;
826 }
827
828 // If we reach this point, we're really out of memory. Try every trick
829 // we can to reclaim memory. Force collection of soft references. Force
830 // a complete compaction of the heap. Any additional methods for finding
831 // free memory should be here, especially if they are expensive. If this
832 // attempt fails, an OOM exception will be thrown.
833 {
834 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
835
836 gch->do_collection(true /* full */,
837 true /* clear_all_soft_refs */,
838 size /* size */,
839 is_tlab /* is_tlab */,
840 number_of_generations() - 1 /* max_level */);
841 }
842
843 result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
844 if (result != NULL) {
845 assert(gch->is_in_reserved(result), "result not in heap");
846 return result;
847 }
848
849 assert(!should_clear_all_soft_refs(),
850 "Flag should have been handled and cleared prior to this point");
851
852 // What else? We might try synchronous finalization later. If the total
853 // space available is large enough for the allocation, then a more
854 // complete compaction phase than we've tried so far might be
855 // appropriate.
856 return NULL;
857 }
858
859 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
860 ClassLoaderData* loader_data,
861 size_t word_size,
862 Metaspace::MetadataType mdtype) {
863 uint loop_count = 0;
864 uint gc_count = 0;
865 uint full_gc_count = 0;
866
867 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
868
869 do {
870 MetaWord* result = NULL;
871 if (GC_locker::is_active_and_needs_gc()) {
872 // If the GC_locker is active, just expand and allocate.
873 // If that does not succeed, wait if this thread is not
874 // in a critical section itself.
875 result =
876 loader_data->metaspace_non_null()->expand_and_allocate(word_size,
877 mdtype);
878 if (result != NULL) {
879 return result;
880 }
881 JavaThread* jthr = JavaThread::current();
882 if (!jthr->in_critical()) {
883 // Wait for JNI critical section to be exited
884 GC_locker::stall_until_clear();
885 // The GC invoked by the last thread leaving the critical
886 // section will be a young collection and a full collection
887 // is (currently) needed for unloading classes so continue
888 // to the next iteration to get a full GC.
889 continue;
890 } else {
891 if (CheckJNICalls) {
892 fatal("Possible deadlock due to allocating while"
893 " in jni critical section");
894 }
895 return NULL;
896 }
897 }
898
899 { // Need lock to get self consistent gc_count's
900 MutexLocker ml(Heap_lock);
901 gc_count = Universe::heap()->total_collections();
902 full_gc_count = Universe::heap()->total_full_collections();
903 }
904
905 // Generate a VM operation
906 VM_CollectForMetadataAllocation op(loader_data,
907 word_size,
908 mdtype,
909 gc_count,
910 full_gc_count,
911 GCCause::_metadata_GC_threshold);
912 VMThread::execute(&op);
913
914 // If GC was locked out, try again. Check before checking success because the
915 // prologue could have succeeded and the GC still have been locked out.
916 if (op.gc_locked()) {
917 continue;
918 }
919
920 if (op.prologue_succeeded()) {
921 return op.result();
922 }
923 loop_count++;
924 if ((QueuedAllocationWarningCount > 0) &&
925 (loop_count % QueuedAllocationWarningCount == 0)) {
926 warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
927 " size=%d", loop_count, word_size);
928 }
929 } while (true); // Until a GC is done
930 }
931
932 // Return true if any of the following is true:
933 // . the allocation won't fit into the current young gen heap
934 // . gc locker is occupied (jni critical section)
935 // . heap memory is tight -- the most recent previous collection
936 // was a full collection because a partial collection (would
937 // have) failed and is likely to fail again
938 bool GenCollectorPolicy::should_try_older_generation_allocation(
939 size_t word_size) const {
940 GenCollectedHeap* gch = GenCollectedHeap::heap();
941 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
942 return (word_size > heap_word_size(gen0_capacity))
943 || GC_locker::is_active_and_needs_gc()
944 || gch->incremental_collection_failed();
945 }
946
947
948 //
949 // MarkSweepPolicy methods
950 //
951
952 void MarkSweepPolicy::initialize_alignments() {
953 _space_alignment = _gen_alignment = (uintx)Generation::GenGrain;
954 _heap_alignment = compute_heap_alignment();
955 }
956
957 void MarkSweepPolicy::initialize_generations() {
958 _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL);
959 if (_generations == NULL) {
960 vm_exit_during_initialization("Unable to allocate gen spec");
961 }
962
963 if (UseParNewGC) {
964 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
965 } else {
966 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
967 }
968 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
969
970 if (_generations[0] == NULL || _generations[1] == NULL) {
971 vm_exit_during_initialization("Unable to allocate gen spec");
972 }
973 }
974
975 void MarkSweepPolicy::initialize_gc_policy_counters() {
976 // Initialize the policy counters - 2 collectors, 3 generations.
977 if (UseParNewGC) {
978 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
979 } else {
980 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
981 }
982 }