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 void CollectorPolicy::assert_flags() {
63 assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
64 assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
65 assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
66 }
67
68 void CollectorPolicy::assert_size_info() {
69 assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
70 assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
71 assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
72 assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
73 assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
74 assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
75 assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
76 assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
77 }
78
79 void CollectorPolicy::initialize_alignments() {
80 _space_alignment = (uintx) Generation::GenGrain;
81 _heap_alignment = compute_heap_alignment();
82 }
83
84 void CollectorPolicy::initialize_flags() {
85 assert(_space_alignment != 0, "Space alignment not set up properly");
86 assert(_heap_alignment != 0, "Heap alignment not set up properly");
87 assert(_heap_alignment >= _space_alignment,
88 err_msg("heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
89 _heap_alignment, _space_alignment));
90 assert(_heap_alignment % _space_alignment == 0,
91 err_msg("heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
92 _heap_alignment, _space_alignment));
93
94 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
95 if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
96 vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
97 }
98 if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
99 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
100 }
101 _max_heap_size_cmdline = true;
102 }
103
104 // Check heap parameter properties
105 if (InitialHeapSize < M) {
106 vm_exit_during_initialization("Too small initial heap");
107 }
108 if (_min_heap_byte_size < M) {
109 vm_exit_during_initialization("Too small minimum heap");
110 }
111
112 // User inputs from -Xmx and -Xms must be aligned
113 _min_heap_byte_size = align_size_up(_min_heap_byte_size, _heap_alignment);
114 uintx alignedInitialHeapSize = align_size_up(InitialHeapSize, _heap_alignment);
115 uintx alignedMaxHeapSize = align_size_up(MaxHeapSize, _heap_alignment);
116
117 // Write back to flags if the values changed
118 if (alignedInitialHeapSize != InitialHeapSize) {
119 FLAG_SET_ERGO(uintx, InitialHeapSize, alignedInitialHeapSize);
120 }
121 if (alignedMaxHeapSize != MaxHeapSize) {
122 FLAG_SET_ERGO(uintx, MaxHeapSize, alignedMaxHeapSize);
123 }
124
125 if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
126 InitialHeapSize < _min_heap_byte_size) {
127 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
128 }
129 if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
130 FLAG_SET_ERGO(uintx, MaxHeapSize, InitialHeapSize);
131 } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
132 FLAG_SET_ERGO(uintx, InitialHeapSize, MaxHeapSize);
133 if (InitialHeapSize < _min_heap_byte_size) {
134 _min_heap_byte_size = InitialHeapSize;
135 }
136 }
137
138 _initial_heap_byte_size = InitialHeapSize;
139 _max_heap_byte_size = MaxHeapSize;
140
141 FLAG_SET_ERGO(uintx, MinHeapDeltaBytes, align_size_up(MinHeapDeltaBytes, _space_alignment));
142
143 CollectorPolicy::assert_flags();
144 }
145
146 void CollectorPolicy::initialize_size_info() {
147 if (PrintGCDetails && Verbose) {
148 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap "
149 SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
150 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
151 }
152
153 CollectorPolicy::assert_size_info();
154 }
155
156 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
157 bool result = _should_clear_all_soft_refs;
158 set_should_clear_all_soft_refs(false);
159 return result;
160 }
161
162 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
163 int max_covered_regions) {
164 return new CardTableRS(whole_heap, max_covered_regions);
165 }
166
167 void CollectorPolicy::cleared_all_soft_refs() {
168 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
169 // have been cleared in the last collection but if the gc overhear
170 // limit continues to be near, SoftRefs should still be cleared.
171 if (size_policy() != NULL) {
172 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
173 }
174 _all_soft_refs_clear = true;
175 }
176
177 size_t CollectorPolicy::compute_heap_alignment() {
178 // The card marking array and the offset arrays for old generations are
179 // committed in os pages as well. Make sure they are entirely full (to
180 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
181 // byte entry and the os page size is 4096, the maximum heap size should
182 // be 512*4096 = 2MB aligned.
183
184 // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable
185 // is supported.
186 // Requirements of any new remembered set implementations must be added here.
187 size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
188
189 // Parallel GC does its own alignment of the generations to avoid requiring a
190 // large page (256M on some platforms) for the permanent generation. The
191 // other collectors should also be updated to do their own alignment and then
192 // this use of lcm() should be removed.
193 if (UseLargePages && !UseParallelGC) {
194 // in presence of large pages we have to make sure that our
195 // alignment is large page aware
196 alignment = lcm(os::large_page_size(), alignment);
197 }
198
199 return alignment;
200 }
201
202 // GenCollectorPolicy methods.
203
204 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
205 return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
206 }
207
208 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
209 size_t maximum_size) {
210 size_t max_minus = maximum_size - _gen_alignment;
211 return desired_size < max_minus ? desired_size : max_minus;
212 }
213
214
215 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
216 size_t init_promo_size,
217 size_t init_survivor_size) {
218 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
219 _size_policy = new AdaptiveSizePolicy(init_eden_size,
220 init_promo_size,
221 init_survivor_size,
222 max_gc_pause_sec,
223 GCTimeRatio);
224 }
225
226 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
227 // The young generation must be aligned and have room for eden + two survivors
228 return align_size_up(3 * _space_alignment, _gen_alignment);
229 }
230
231 void GenCollectorPolicy::assert_flags() {
232 CollectorPolicy::assert_flags();
233 assert(NewSize >= _min_gen0_size, "Ergonomics decided on a too small young gen size");
234 assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
235 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
236 assert(NewSize % _gen_alignment == 0, "NewSize alignment");
237 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
238 }
239
240 void TwoGenerationCollectorPolicy::assert_flags() {
241 GenCollectorPolicy::assert_flags();
242 assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
243 assert(OldSize % _gen_alignment == 0, "OldSize alignment");
244 }
245
246 void GenCollectorPolicy::assert_size_info() {
247 CollectorPolicy::assert_size_info();
248 // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
249 assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
250 assert(NewSize == _initial_gen0_size, "Discrepancy between NewSize flag and local storage");
251 assert(MaxNewSize == _max_gen0_size, "Discrepancy between MaxNewSize flag and local storage");
252 assert(_min_gen0_size <= _initial_gen0_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
253 assert(_initial_gen0_size <= _max_gen0_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
254 assert(_min_gen0_size % _gen_alignment == 0, "_min_gen0_size alignment");
255 assert(_initial_gen0_size % _gen_alignment == 0, "_initial_gen0_size alignment");
256 assert(_max_gen0_size % _gen_alignment == 0, "_max_gen0_size alignment");
257 }
258
259 void TwoGenerationCollectorPolicy::assert_size_info() {
260 GenCollectorPolicy::assert_size_info();
261 assert(OldSize == _initial_gen1_size, "Discrepancy between OldSize flag and local storage");
262 assert(_min_gen1_size <= _initial_gen1_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
263 assert(_initial_gen1_size <= _max_gen1_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
264 assert(_max_gen1_size % _gen_alignment == 0, "_max_gen1_size alignment");
265 assert(_initial_gen1_size % _gen_alignment == 0, "_initial_gen1_size alignment");
266 assert(_max_heap_byte_size <= (_max_gen0_size + _max_gen1_size), "Total maximum heap sizes must be sum of generation maximum sizes");
267 }
268
269 void GenCollectorPolicy::initialize_alignments() {
270 CollectorPolicy::initialize_alignments();
271 _gen_alignment = default_gen_alignment();
272 }
273
274 void GenCollectorPolicy::initialize_flags() {
275 CollectorPolicy::initialize_flags();
276
277 assert(_gen_alignment != 0, "Generation alignment not set up properly");
278 assert(_heap_alignment >= _gen_alignment,
279 err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
280 _heap_alignment, _gen_alignment));
281 assert(_gen_alignment % _space_alignment == 0,
282 err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
283 _gen_alignment, _space_alignment));
284
285 // All generational heaps have a youngest gen; handle those flags here
286 if (FLAG_IS_CMDLINE(NewSize) && FLAG_IS_CMDLINE(MaxNewSize) && NewSize > MaxNewSize) {
287 vm_exit_during_initialization("Initial young gen size set larger than the maximum young gen size");
288 }
289
290 // Make sure the heap is large enough for two generations
291 uintx smallestNewSize = young_gen_size_lower_bound();
292 uintx smallestHeapSize = align_size_up(smallestNewSize + align_size_up(_space_alignment, _gen_alignment),
293 _heap_alignment);
294 if (MaxHeapSize < smallestHeapSize) {
295 FLAG_SET_ERGO(uintx, MaxHeapSize, smallestHeapSize);
296 _max_heap_byte_size = MaxHeapSize;
297 }
298 // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
299 if (_min_heap_byte_size < smallestHeapSize) {
300 _min_heap_byte_size = smallestHeapSize;
301 if (InitialHeapSize < _min_heap_byte_size) {
302 FLAG_SET_ERGO(uintx, InitialHeapSize, smallestHeapSize);
303 _initial_heap_byte_size = smallestHeapSize;
304 }
305 }
306
307 // Now take the actual NewSize into account. We will silently increase NewSize
308 // if the user specified a smaller value.
309 smallestNewSize = MAX2(smallestNewSize, (uintx)align_size_down(NewSize, _gen_alignment));
310 if (smallestNewSize != NewSize) {
311 FLAG_SET_ERGO(uintx, NewSize, smallestNewSize);
312 }
313 _initial_gen0_size = NewSize;
314
315 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
316 uintx minNewSize = MAX2(_gen_alignment, _min_gen0_size);
317
318 if (MaxNewSize >= MaxHeapSize) {
319 // Make sure there is room for an old generation
320 uintx smallerMaxNewSize = MaxHeapSize - _gen_alignment;
321 if (FLAG_IS_CMDLINE(MaxNewSize)) {
322 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
323 "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.",
324 MaxNewSize/K, MaxHeapSize/K, smallerMaxNewSize/K);
325 }
326 FLAG_SET_ERGO(uintx, MaxNewSize, smallerMaxNewSize);
327 if (NewSize > MaxNewSize) {
328 FLAG_SET_ERGO(uintx, NewSize, MaxNewSize);
329 _initial_gen0_size = NewSize;
330 }
331 } else if (MaxNewSize < minNewSize) {
332 FLAG_SET_ERGO(uintx, MaxNewSize, minNewSize);
333 } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) {
334 FLAG_SET_ERGO(uintx, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment));
335 }
336 _max_gen0_size = MaxNewSize;
337 }
338
339 if (NewSize > MaxNewSize) {
340 // At this point this should only happen if the user specifies a large NewSize or
341 // a small (but not too small) MaxNewSize.
342 if (FLAG_IS_CMDLINE(NewSize)) {
343 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
344 "A new generation size of " SIZE_FORMAT "k will be used.",
345 NewSize/K, MaxNewSize/K, MaxNewSize/K);
346 }
347 FLAG_SET_ERGO(uintx, NewSize, MaxNewSize);
348 _initial_gen0_size = NewSize;
349 }
350
351 if (SurvivorRatio < 1 || NewRatio < 1) {
352 vm_exit_during_initialization("Invalid young gen ratio specified");
353 }
354
355 GenCollectorPolicy::assert_flags();
356 }
357
358 void TwoGenerationCollectorPolicy::initialize_flags() {
359 GenCollectorPolicy::initialize_flags();
360
361 if (!is_size_aligned(OldSize, _gen_alignment)) {
362 FLAG_SET_ERGO(uintx, OldSize, align_size_down(OldSize, _gen_alignment));
363 }
364
365 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
366 // NewRatio will be used later to set the young generation size so we use
367 // it to calculate how big the heap should be based on the requested OldSize
368 // and NewRatio.
369 assert(NewRatio > 0, "NewRatio should have been set up earlier");
370 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
371
372 calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment);
373 FLAG_SET_ERGO(uintx, MaxHeapSize, calculated_heapsize);
374 _max_heap_byte_size = MaxHeapSize;
375 FLAG_SET_ERGO(uintx, InitialHeapSize, calculated_heapsize);
376 _initial_heap_byte_size = InitialHeapSize;
377 }
378
379 // adjust max heap size if necessary
380 if (NewSize + OldSize > MaxHeapSize) {
381 if (_max_heap_size_cmdline) {
382 // somebody set a maximum heap size with the intention that we should not
383 // exceed it. Adjust New/OldSize as necessary.
384 uintx calculated_size = NewSize + OldSize;
385 double shrink_factor = (double) MaxHeapSize / calculated_size;
386 uintx smallerNewSize = align_size_down((uintx)(NewSize * shrink_factor), _gen_alignment);
387 FLAG_SET_ERGO(uintx, NewSize, MAX2(young_gen_size_lower_bound(), smallerNewSize));
388 _initial_gen0_size = NewSize;
389
390 // OldSize is already aligned because above we aligned MaxHeapSize to
391 // _heap_alignment, and we just made sure that NewSize is aligned to
392 // _gen_alignment. In initialize_flags() we verified that _heap_alignment
393 // is a multiple of _gen_alignment.
394 FLAG_SET_ERGO(uintx, OldSize, MaxHeapSize - NewSize);
395 } else {
396 FLAG_SET_ERGO(uintx, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment));
397 _max_heap_byte_size = MaxHeapSize;
398 }
399 }
400
401 always_do_update_barrier = UseConcMarkSweepGC;
402 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
443 // the generations minimum and initial must be the
444 // same as its maximum.
445 _min_gen0_size = max_new_size;
446 _initial_gen0_size = max_new_size;
447 _max_gen0_size = max_new_size;
448 } else {
449 size_t desired_new_size = 0;
450 if (!FLAG_IS_DEFAULT(NewSize)) {
451 // If NewSize is set ergonomically (for example by cms), it
452 // would make sense to use it. If it is used, also use it
453 // to set the initial size. Although there is no reason
454 // the minimum size and the initial size have to be the same,
455 // the current implementation gets into trouble during the calculation
456 // of the tenured generation sizes if they are different.
457 // Note that this makes the initial size and the minimum size
458 // generally small compared to the NewRatio calculation.
459 _min_gen0_size = NewSize;
460 desired_new_size = NewSize;
461 max_new_size = MAX2(max_new_size, NewSize);
462 } else {
463 // For the case where NewSize is the default, use NewRatio
464 // to size the minimum and initial generation sizes.
465 // Use the default NewSize as the floor for these values. If
466 // NewRatio is overly large, the resulting sizes can be too
467 // small.
468 _min_gen0_size = MAX2(scale_by_NewRatio_aligned(_min_heap_byte_size), NewSize);
469 desired_new_size =
470 MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize);
471 }
472
473 assert(_min_gen0_size > 0, "Sanity check");
474 _initial_gen0_size = desired_new_size;
475 _max_gen0_size = max_new_size;
476
477 // At this point the desirable initial and minimum sizes have been
478 // determined without regard to the maximum sizes.
479
480 // Bound the sizes by the corresponding overall heap sizes.
481 _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size);
482 _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size);
483 _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size);
484
485 // At this point all three sizes have been checked against the
486 // maximum sizes but have not been checked for consistency
487 // among the three.
488
489 // Final check min <= initial <= max
490 _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size);
491 _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size);
492 _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size);
493 }
494
495 // Write back to flags if necessary
496 if (NewSize != _initial_gen0_size) {
497 FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);
498 }
499
500 if (MaxNewSize != _max_gen0_size) {
501 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
502 }
503
504 if (PrintGCDetails && Verbose) {
505 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
506 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
507 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
508 }
509
510 GenCollectorPolicy::assert_size_info();
511 }
512
513 // Call this method during the sizing of the gen1 to make
514 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has
515 // the most freedom in sizing because it is done before the
516 // policy for gen1 is applied. Once gen1 policies have been applied,
517 // there may be conflicts in the shape of the heap and this method
518 // is used to make the needed adjustments. The application of the
519 // policies could be more sophisticated (iterative for example) but
520 // keeping it simple also seems a worthwhile goal.
521 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
522 size_t* gen1_size_ptr,
523 const size_t heap_size,
524 const size_t min_gen1_size) {
525 bool result = false;
526
527 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
528 uintx smallestNewSize = young_gen_size_lower_bound();
529 if ((heap_size < (*gen0_size_ptr + min_gen1_size)) &&
530 (heap_size >= min_gen1_size + smallestNewSize)) {
531 // Adjust gen0 down to accommodate min_gen1_size
532 *gen0_size_ptr = align_size_down_bounded(heap_size - min_gen1_size, _gen_alignment);
533 assert(*gen0_size_ptr > 0, "Min gen0 is too large");
534 result = true;
535 } else {
536 *gen1_size_ptr = align_size_down_bounded(heap_size - *gen0_size_ptr, _gen_alignment);
537 }
538 }
539 return result;
540 }
541
542 // Minimum sizes of the generations may be different than
543 // the initial sizes. An inconsistently is permitted here
544 // in the total size that can be specified explicitly by
545 // command line specification of OldSize and NewSize and
546 // also a command line specification of -Xms. Issue a warning
547 // but allow the values to pass.
548
549 void TwoGenerationCollectorPolicy::initialize_size_info() {
550 GenCollectorPolicy::initialize_size_info();
551
552 // At this point the minimum, initial and maximum sizes
553 // of the overall heap and of gen0 have been determined.
554 // The maximum gen1 size can be determined from the maximum gen0
555 // and maximum heap size since no explicit flags exits
556 // for setting the gen1 maximum.
557 _max_gen1_size = MAX2(_max_heap_byte_size - _max_gen0_size, _gen_alignment);
558
559 // If no explicit command line flag has been set for the
560 // gen1 size, use what is left for gen1.
561 if (!FLAG_IS_CMDLINE(OldSize)) {
562 // The user has not specified any value but the ergonomics
563 // may have chosen a value (which may or may not be consistent
564 // with the overall heap size). In either case make
565 // the minimum, maximum and initial sizes consistent
566 // with the gen0 sizes and the overall heap sizes.
567 _min_gen1_size = MAX2(_min_heap_byte_size - _min_gen0_size, _gen_alignment);
568 _initial_gen1_size = MAX2(_initial_heap_byte_size - _initial_gen0_size, _gen_alignment);
569 // _max_gen1_size has already been made consistent above
570 FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);
571 } else {
572 // It's been explicitly set on the command line. Use the
573 // OldSize and then determine the consequences.
574 _min_gen1_size = MIN2(OldSize, _min_heap_byte_size - _min_gen0_size);
575 _initial_gen1_size = OldSize;
576
577 // If the user has explicitly set an OldSize that is inconsistent
578 // with other command line flags, issue a warning.
579 // The generation minimums and the overall heap mimimum should
580 // be within one generation alignment.
581 if ((_min_gen1_size + _min_gen0_size + _gen_alignment) < _min_heap_byte_size) {
582 warning("Inconsistency between minimum heap size and minimum "
583 "generation sizes: using minimum heap = " SIZE_FORMAT,
584 _min_heap_byte_size);
585 }
586 if (OldSize > _max_gen1_size) {
587 warning("Inconsistency between maximum heap size and maximum "
588 "generation sizes: using maximum heap = " SIZE_FORMAT
589 " -XX:OldSize flag is being ignored",
590 _max_heap_byte_size);
591 }
592 // If there is an inconsistency between the OldSize and the minimum and/or
593 // initial size of gen0, since OldSize was explicitly set, OldSize wins.
594 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
595 _min_heap_byte_size, _min_gen1_size)) {
596 if (PrintGCDetails && Verbose) {
597 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
598 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
599 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
600 }
601 }
602 // Initial size
603 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
604 _initial_heap_byte_size, _initial_gen1_size)) {
605 if (PrintGCDetails && Verbose) {
606 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
607 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
608 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
609 }
610 }
611 }
612 // Enforce the maximum gen1 size.
613 _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size);
614
615 // Check that min gen1 <= initial gen1 <= max gen1
616 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size);
617 _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size);
618
619 // Write back to flags if necessary
620 if (NewSize != _initial_gen0_size) {
621 FLAG_SET_ERGO(uintx, NewSize, _max_gen0_size);
622 }
623
624 if (MaxNewSize != _max_gen0_size) {
625 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
626 }
627
628 if (OldSize != _initial_gen1_size) {
629 FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);
630 }
631
632 if (PrintGCDetails && Verbose) {
633 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 "
634 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT,
635 _min_gen1_size, _initial_gen1_size, _max_gen1_size);
636 }
637
638 TwoGenerationCollectorPolicy::assert_size_info();
639 }
640
641 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
642 bool is_tlab,
643 bool* gc_overhead_limit_was_exceeded) {
644 GenCollectedHeap *gch = GenCollectedHeap::heap();
645
646 debug_only(gch->check_for_valid_allocation_state());
647 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
648
649 // In general gc_overhead_limit_was_exceeded should be false so
650 // set it so here and reset it to true only if the gc time
651 // limit is being exceeded as checked below.
652 *gc_overhead_limit_was_exceeded = false;
653
654 HeapWord* result = NULL;
655
656 // Loop until the allocation is satisified,
657 // or unsatisfied after GC.
658 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
659 HandleMark hm; // discard any handles allocated in each iteration
660
661 // First allocation attempt is lock-free.
662 Generation *gen0 = gch->get_gen(0);
663 assert(gen0->supports_inline_contig_alloc(),
664 "Otherwise, must do alloc within heap lock");
665 if (gen0->should_allocate(size, is_tlab)) {
666 result = gen0->par_allocate(size, is_tlab);
667 if (result != NULL) {
668 assert(gch->is_in_reserved(result), "result not in heap");
669 return result;
670 }
671 }
672 unsigned int gc_count_before; // read inside the Heap_lock locked region
673 {
674 MutexLocker ml(Heap_lock);
675 if (PrintGC && Verbose) {
676 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
677 " attempting locked slow path allocation");
678 }
679 // Note that only large objects get a shot at being
680 // allocated in later generations.
681 bool first_only = ! should_try_older_generation_allocation(size);
682
683 result = gch->attempt_allocation(size, is_tlab, first_only);
684 if (result != NULL) {
685 assert(gch->is_in_reserved(result), "result not in heap");
686 return result;
687 }
688
689 if (GC_locker::is_active_and_needs_gc()) {
690 if (is_tlab) {
691 return NULL; // Caller will retry allocating individual object
692 }
693 if (!gch->is_maximal_no_gc()) {
694 // Try and expand heap to satisfy request
695 result = expand_heap_and_allocate(size, is_tlab);
696 // result could be null if we are out of space
697 if (result != NULL) {
698 return result;
699 }
700 }
701
702 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
703 return NULL; // we didn't get to do a GC and we didn't get any memory
704 }
705
706 // If this thread is not in a jni critical section, we stall
707 // the requestor until the critical section has cleared and
708 // GC allowed. When the critical section clears, a GC is
709 // initiated by the last thread exiting the critical section; so
710 // we retry the allocation sequence from the beginning of the loop,
711 // rather than causing more, now probably unnecessary, GC attempts.
712 JavaThread* jthr = JavaThread::current();
713 if (!jthr->in_critical()) {
714 MutexUnlocker mul(Heap_lock);
715 // Wait for JNI critical section to be exited
716 GC_locker::stall_until_clear();
717 gclocker_stalled_count += 1;
718 continue;
719 } else {
720 if (CheckJNICalls) {
721 fatal("Possible deadlock due to allocating while"
722 " in jni critical section");
723 }
724 return NULL;
725 }
726 }
727
728 // Read the gc count while the heap lock is held.
729 gc_count_before = Universe::heap()->total_collections();
730 }
731
732 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
733 VMThread::execute(&op);
734 if (op.prologue_succeeded()) {
735 result = op.result();
736 if (op.gc_locked()) {
737 assert(result == NULL, "must be NULL if gc_locked() is true");
738 continue; // retry and/or stall as necessary
739 }
740
741 // Allocation has failed and a collection
742 // has been done. If the gc time limit was exceeded the
743 // this time, return NULL so that an out-of-memory
744 // will be thrown. Clear gc_overhead_limit_exceeded
745 // so that the overhead exceeded does not persist.
746
747 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
748 const bool softrefs_clear = all_soft_refs_clear();
749
750 if (limit_exceeded && softrefs_clear) {
751 *gc_overhead_limit_was_exceeded = true;
752 size_policy()->set_gc_overhead_limit_exceeded(false);
753 if (op.result() != NULL) {
754 CollectedHeap::fill_with_object(op.result(), size);
755 }
756 return NULL;
757 }
758 assert(result == NULL || gch->is_in_reserved(result),
759 "result not in heap");
760 return result;
761 }
762
763 // Give a warning if we seem to be looping forever.
764 if ((QueuedAllocationWarningCount > 0) &&
765 (try_count % QueuedAllocationWarningCount == 0)) {
766 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
767 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
768 }
769 }
770 }
771
772 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
773 bool is_tlab) {
774 GenCollectedHeap *gch = GenCollectedHeap::heap();
775 HeapWord* result = NULL;
776 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
777 Generation *gen = gch->get_gen(i);
778 if (gen->should_allocate(size, is_tlab)) {
779 result = gen->expand_and_allocate(size, is_tlab);
780 }
781 }
782 assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
783 return result;
784 }
785
786 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
787 bool is_tlab) {
788 GenCollectedHeap *gch = GenCollectedHeap::heap();
789 GCCauseSetter x(gch, GCCause::_allocation_failure);
790 HeapWord* result = NULL;
791
792 assert(size != 0, "Precondition violated");
793 if (GC_locker::is_active_and_needs_gc()) {
794 // GC locker is active; instead of a collection we will attempt
795 // to expand the heap, if there's room for expansion.
796 if (!gch->is_maximal_no_gc()) {
797 result = expand_heap_and_allocate(size, is_tlab);
798 }
799 return result; // could be null if we are out of space
800 } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
801 // Do an incremental collection.
802 gch->do_collection(false /* full */,
803 false /* clear_all_soft_refs */,
804 size /* size */,
805 is_tlab /* is_tlab */,
806 number_of_generations() - 1 /* max_level */);
807 } else {
808 if (Verbose && PrintGCDetails) {
809 gclog_or_tty->print(" :: Trying full because partial may fail :: ");
810 }
811 // Try a full collection; see delta for bug id 6266275
812 // for the original code and why this has been simplified
813 // with from-space allocation criteria modified and
814 // such allocation moved out of the safepoint path.
815 gch->do_collection(true /* full */,
816 false /* clear_all_soft_refs */,
817 size /* size */,
818 is_tlab /* is_tlab */,
819 number_of_generations() - 1 /* max_level */);
820 }
821
822 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
823
824 if (result != NULL) {
825 assert(gch->is_in_reserved(result), "result not in heap");
826 return result;
827 }
828
829 // OK, collection failed, try expansion.
830 result = expand_heap_and_allocate(size, is_tlab);
831 if (result != NULL) {
832 return result;
833 }
834
835 // If we reach this point, we're really out of memory. Try every trick
836 // we can to reclaim memory. Force collection of soft references. Force
837 // a complete compaction of the heap. Any additional methods for finding
838 // free memory should be here, especially if they are expensive. If this
839 // attempt fails, an OOM exception will be thrown.
840 {
841 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
842
843 gch->do_collection(true /* full */,
844 true /* clear_all_soft_refs */,
845 size /* size */,
846 is_tlab /* is_tlab */,
847 number_of_generations() - 1 /* max_level */);
848 }
849
850 result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
851 if (result != NULL) {
852 assert(gch->is_in_reserved(result), "result not in heap");
853 return result;
854 }
855
856 assert(!should_clear_all_soft_refs(),
857 "Flag should have been handled and cleared prior to this point");
858
859 // What else? We might try synchronous finalization later. If the total
860 // space available is large enough for the allocation, then a more
861 // complete compaction phase than we've tried so far might be
862 // appropriate.
863 return NULL;
864 }
865
866 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
867 ClassLoaderData* loader_data,
868 size_t word_size,
869 Metaspace::MetadataType mdtype) {
870 uint loop_count = 0;
871 uint gc_count = 0;
872 uint full_gc_count = 0;
873
874 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
875
876 do {
877 MetaWord* result = NULL;
878 if (GC_locker::is_active_and_needs_gc()) {
879 // If the GC_locker is active, just expand and allocate.
880 // If that does not succeed, wait if this thread is not
881 // in a critical section itself.
882 result =
883 loader_data->metaspace_non_null()->expand_and_allocate(word_size,
884 mdtype);
885 if (result != NULL) {
886 return result;
887 }
888 JavaThread* jthr = JavaThread::current();
889 if (!jthr->in_critical()) {
890 // Wait for JNI critical section to be exited
891 GC_locker::stall_until_clear();
892 // The GC invoked by the last thread leaving the critical
893 // section will be a young collection and a full collection
894 // is (currently) needed for unloading classes so continue
895 // to the next iteration to get a full GC.
896 continue;
897 } else {
898 if (CheckJNICalls) {
899 fatal("Possible deadlock due to allocating while"
900 " in jni critical section");
901 }
902 return NULL;
903 }
904 }
905
906 { // Need lock to get self consistent gc_count's
907 MutexLocker ml(Heap_lock);
908 gc_count = Universe::heap()->total_collections();
909 full_gc_count = Universe::heap()->total_full_collections();
910 }
911
912 // Generate a VM operation
913 VM_CollectForMetadataAllocation op(loader_data,
914 word_size,
915 mdtype,
916 gc_count,
917 full_gc_count,
918 GCCause::_metadata_GC_threshold);
919 VMThread::execute(&op);
920
921 // If GC was locked out, try again. Check
922 // before checking success because the prologue
923 // could have succeeded and the GC still have
924 // been locked out.
925 if (op.gc_locked()) {
926 continue;
927 }
928
929 if (op.prologue_succeeded()) {
930 return op.result();
931 }
932 loop_count++;
933 if ((QueuedAllocationWarningCount > 0) &&
934 (loop_count % QueuedAllocationWarningCount == 0)) {
935 warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
936 " size=%d", loop_count, word_size);
937 }
938 } while (true); // Until a GC is done
939 }
940
941 // Return true if any of the following is true:
942 // . the allocation won't fit into the current young gen heap
943 // . gc locker is occupied (jni critical section)
944 // . heap memory is tight -- the most recent previous collection
945 // was a full collection because a partial collection (would
946 // have) failed and is likely to fail again
947 bool GenCollectorPolicy::should_try_older_generation_allocation(
948 size_t word_size) const {
949 GenCollectedHeap* gch = GenCollectedHeap::heap();
950 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
951 return (word_size > heap_word_size(gen0_capacity))
952 || GC_locker::is_active_and_needs_gc()
953 || gch->incremental_collection_failed();
954 }
955
956
957 //
958 // MarkSweepPolicy methods
959 //
960
961 void MarkSweepPolicy::initialize_generations() {
962 _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL);
963 if (_generations == NULL) {
964 vm_exit_during_initialization("Unable to allocate gen spec");
965 }
966
967 if (UseParNewGC) {
968 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
969 } else {
970 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
971 }
972 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
973
974 if (_generations[0] == NULL || _generations[1] == NULL) {
975 vm_exit_during_initialization("Unable to allocate gen spec");
976 }
977 }
978
979 void MarkSweepPolicy::initialize_gc_policy_counters() {
980 // initialize the policy counters - 2 collectors, 3 generations
981 if (UseParNewGC) {
982 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
983 } else {
984 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
985 }
986 }