1 /*
2 * Copyright (c) 2001, 2016, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/adaptiveSizePolicy.hpp"
27 #include "gc/shared/cardTableRS.hpp"
28 #include "gc/shared/collectorPolicy.hpp"
29 #include "gc/shared/gcLocker.inline.hpp"
30 #include "gc/shared/gcPolicyCounters.hpp"
31 #include "gc/shared/genCollectedHeap.hpp"
32 #include "gc/shared/generationSpec.hpp"
33 #include "gc/shared/space.hpp"
34 #include "gc/shared/vmGCOperations.hpp"
35 #include "logging/log.hpp"
36 #include "memory/universe.hpp"
37 #include "runtime/arguments.hpp"
38 #include "runtime/globals_extension.hpp"
39 #include "runtime/handles.inline.hpp"
40 #include "runtime/java.hpp"
41 #include "runtime/thread.inline.hpp"
42 #include "runtime/vmThread.hpp"
43 #include "utilities/align.hpp"
44 #include "utilities/macros.hpp"
45
46 // CollectorPolicy methods
47
48 CollectorPolicy::CollectorPolicy() :
49 _space_alignment(0),
50 _heap_alignment(0),
51 _initial_heap_byte_size(InitialHeapSize),
52 _max_heap_byte_size(MaxHeapSize),
53 _min_heap_byte_size(Arguments::min_heap_size()),
54 _should_clear_all_soft_refs(false),
55 _all_soft_refs_clear(false)
56 {}
57
58 #ifdef ASSERT
59 void CollectorPolicy::assert_flags() {
60 assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
61 assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
62 assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
63 }
64
65 void CollectorPolicy::assert_size_info() {
66 assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
67 assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
68 assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
69 assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
70 assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
71 assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
72 assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
73 assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
74 }
75 #endif // ASSERT
76
77 void CollectorPolicy::initialize_flags() {
78 assert(_space_alignment != 0, "Space alignment not set up properly");
79 assert(_heap_alignment != 0, "Heap alignment not set up properly");
80 assert(_heap_alignment >= _space_alignment,
81 "heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
82 _heap_alignment, _space_alignment);
83 assert(_heap_alignment % _space_alignment == 0,
84 "heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
85 _heap_alignment, _space_alignment);
86
87 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
88 if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
89 vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
90 }
91 if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
92 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
93 }
94 }
95
96 // Check heap parameter properties
97 if (MaxHeapSize < 2 * M) {
98 vm_exit_during_initialization("Too small maximum heap");
99 }
100 if (InitialHeapSize < M) {
101 vm_exit_during_initialization("Too small initial heap");
102 }
103 if (_min_heap_byte_size < M) {
104 vm_exit_during_initialization("Too small minimum heap");
105 }
106
107 // User inputs from -Xmx and -Xms must be aligned
108 _min_heap_byte_size = align_up(_min_heap_byte_size, _heap_alignment);
109 size_t aligned_initial_heap_size = align_up(InitialHeapSize, _heap_alignment);
110 size_t aligned_max_heap_size = align_up(MaxHeapSize, _heap_alignment);
111
112 // Write back to flags if the values changed
113 if (aligned_initial_heap_size != InitialHeapSize) {
114 FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size);
115 }
116 if (aligned_max_heap_size != MaxHeapSize) {
117 FLAG_SET_ERGO(size_t, MaxHeapSize, aligned_max_heap_size);
118 }
119
120 if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
121 InitialHeapSize < _min_heap_byte_size) {
122 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
123 }
124 if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
125 FLAG_SET_ERGO(size_t, MaxHeapSize, InitialHeapSize);
126 } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
127 FLAG_SET_ERGO(size_t, InitialHeapSize, MaxHeapSize);
128 if (InitialHeapSize < _min_heap_byte_size) {
129 _min_heap_byte_size = InitialHeapSize;
130 }
131 }
132
133 _initial_heap_byte_size = InitialHeapSize;
134 _max_heap_byte_size = MaxHeapSize;
135
136 FLAG_SET_ERGO(size_t, MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, _space_alignment));
137
138 DEBUG_ONLY(CollectorPolicy::assert_flags();)
139 }
140
141 void CollectorPolicy::initialize_size_info() {
142 log_debug(gc, heap)("Minimum heap " SIZE_FORMAT " Initial heap " SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
143 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
144
145 DEBUG_ONLY(CollectorPolicy::assert_size_info();)
146 }
147
148 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
149 bool result = _should_clear_all_soft_refs;
150 set_should_clear_all_soft_refs(false);
151 return result;
152 }
153
154 void CollectorPolicy::cleared_all_soft_refs() {
155 _all_soft_refs_clear = true;
156 }
157
158 size_t CollectorPolicy::compute_heap_alignment() {
159 // The card marking array and the offset arrays for old generations are
160 // committed in os pages as well. Make sure they are entirely full (to
161 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
162 // byte entry and the os page size is 4096, the maximum heap size should
163 // be 512*4096 = 2MB aligned.
164
165 size_t alignment = CardTableRS::ct_max_alignment_constraint();
166
167 if (UseLargePages) {
168 // In presence of large pages we have to make sure that our
169 // alignment is large page aware.
170 alignment = lcm(os::large_page_size(), alignment);
171 }
172
173 return alignment;
174 }
175
176 // GenCollectorPolicy methods
177
178 GenCollectorPolicy::GenCollectorPolicy() :
179 _min_young_size(0),
180 _initial_young_size(0),
181 _max_young_size(0),
182 _min_old_size(0),
183 _initial_old_size(0),
184 _max_old_size(0),
185 _gen_alignment(0),
186 _young_gen_spec(NULL),
187 _old_gen_spec(NULL),
188 _size_policy(NULL)
189 {}
190
191 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
192 return align_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
193 }
194
195 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
196 size_t maximum_size) {
197 size_t max_minus = maximum_size - _gen_alignment;
198 return desired_size < max_minus ? desired_size : max_minus;
199 }
200
201
202 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
203 size_t init_promo_size,
204 size_t init_survivor_size) {
205 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
206 _size_policy = new AdaptiveSizePolicy(init_eden_size,
207 init_promo_size,
208 init_survivor_size,
209 max_gc_pause_sec,
210 GCTimeRatio);
211 }
212
213 void GenCollectorPolicy::cleared_all_soft_refs() {
214 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
215 // have been cleared in the last collection but if the gc overhear
216 // limit continues to be near, SoftRefs should still be cleared.
217 if (size_policy() != NULL) {
218 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
219 }
220
221 CollectorPolicy::cleared_all_soft_refs();
222 }
223
224 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
225 // The young generation must be aligned and have room for eden + two survivors
226 return align_up(3 * _space_alignment, _gen_alignment);
227 }
228
229 size_t GenCollectorPolicy::old_gen_size_lower_bound() {
230 return align_up(_space_alignment, _gen_alignment);
231 }
232
233 #ifdef ASSERT
234 void GenCollectorPolicy::assert_flags() {
235 CollectorPolicy::assert_flags();
236 assert(NewSize >= _min_young_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 assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
242 assert(OldSize % _gen_alignment == 0, "OldSize alignment");
243 }
244
245 void GenCollectorPolicy::assert_size_info() {
246 CollectorPolicy::assert_size_info();
247 // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
248 assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
249 assert(NewSize == _initial_young_size, "Discrepancy between NewSize flag and local storage");
250 assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage");
251 assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage");
252 assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
253 assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
254 assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment");
255 assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment");
256 assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment");
257 assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size),
258 "Ergonomics made minimum young generation larger than minimum heap");
259 assert(_initial_young_size <= bound_minus_alignment(_initial_young_size, _initial_heap_byte_size),
260 "Ergonomics made initial young generation larger than initial heap");
261 assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size),
262 "Ergonomics made maximum young generation lager than maximum heap");
263 assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
264 assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
265 assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment");
266 assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment");
267 assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes");
268 assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size");
269 assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size");
270 assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size");
271 }
272 #endif // ASSERT
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 "heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
280 _heap_alignment, _gen_alignment);
281 assert(_gen_alignment % _space_alignment == 0,
282 "gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
283 _gen_alignment, _space_alignment);
284 assert(_heap_alignment % _gen_alignment == 0,
285 "heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
286 _heap_alignment, _gen_alignment);
287
288 // All generational heaps have a young gen; handle those flags here
289
290 // Make sure the heap is large enough for two generations
291 size_t smallest_new_size = young_gen_size_lower_bound();
292 size_t smallest_heap_size = align_up(smallest_new_size + old_gen_size_lower_bound(),
293 _heap_alignment);
294 if (MaxHeapSize < smallest_heap_size) {
295 FLAG_SET_ERGO(size_t, MaxHeapSize, smallest_heap_size);
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 < smallest_heap_size) {
300 _min_heap_byte_size = smallest_heap_size;
301 if (InitialHeapSize < _min_heap_byte_size) {
302 FLAG_SET_ERGO(size_t, InitialHeapSize, smallest_heap_size);
303 _initial_heap_byte_size = smallest_heap_size;
304 }
305 }
306
307 // Make sure NewSize allows an old generation to fit even if set on the command line
308 if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) {
309 log_warning(gc, ergo)("NewSize was set larger than initial heap size, will use initial heap size.");
310 FLAG_SET_ERGO(size_t, NewSize, bound_minus_alignment(NewSize, _initial_heap_byte_size));
311 }
312
313 // Now take the actual NewSize into account. We will silently increase NewSize
314 // if the user specified a smaller or unaligned value.
315 size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize);
316 bounded_new_size = MAX2(smallest_new_size, align_down(bounded_new_size, _gen_alignment));
317 if (bounded_new_size != NewSize) {
318 FLAG_SET_ERGO(size_t, NewSize, bounded_new_size);
319 }
320 _min_young_size = smallest_new_size;
321 _initial_young_size = NewSize;
322
323 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
324 if (MaxNewSize >= MaxHeapSize) {
325 // Make sure there is room for an old generation
326 size_t smaller_max_new_size = MaxHeapSize - _gen_alignment;
327 if (FLAG_IS_CMDLINE(MaxNewSize)) {
328 log_warning(gc, ergo)("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
329 "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.",
330 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
331 }
332 FLAG_SET_ERGO(size_t, MaxNewSize, smaller_max_new_size);
333 if (NewSize > MaxNewSize) {
334 FLAG_SET_ERGO(size_t, NewSize, MaxNewSize);
335 _initial_young_size = NewSize;
336 }
337 } else if (MaxNewSize < _initial_young_size) {
338 FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size);
339 } else if (!is_aligned(MaxNewSize, _gen_alignment)) {
340 FLAG_SET_ERGO(size_t, MaxNewSize, align_down(MaxNewSize, _gen_alignment));
341 }
342 _max_young_size = MaxNewSize;
343 }
344
345 if (NewSize > MaxNewSize) {
346 // At this point this should only happen if the user specifies a large NewSize and/or
347 // a small (but not too small) MaxNewSize.
348 if (FLAG_IS_CMDLINE(MaxNewSize)) {
349 log_warning(gc, ergo)("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
350 "A new max generation size of " SIZE_FORMAT "k will be used.",
351 NewSize/K, MaxNewSize/K, NewSize/K);
352 }
353 FLAG_SET_ERGO(size_t, MaxNewSize, NewSize);
354 _max_young_size = MaxNewSize;
355 }
356
357 if (SurvivorRatio < 1 || NewRatio < 1) {
358 vm_exit_during_initialization("Invalid young gen ratio specified");
359 }
360
361 if (OldSize < old_gen_size_lower_bound()) {
362 FLAG_SET_ERGO(size_t, OldSize, old_gen_size_lower_bound());
363 }
364 if (!is_aligned(OldSize, _gen_alignment)) {
365 FLAG_SET_ERGO(size_t, OldSize, align_down(OldSize, _gen_alignment));
366 }
367
368 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
369 // NewRatio will be used later to set the young generation size so we use
370 // it to calculate how big the heap should be based on the requested OldSize
371 // and NewRatio.
372 assert(NewRatio > 0, "NewRatio should have been set up earlier");
373 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
374
375 calculated_heapsize = align_up(calculated_heapsize, _heap_alignment);
376 FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize);
377 _max_heap_byte_size = MaxHeapSize;
378 FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize);
379 _initial_heap_byte_size = InitialHeapSize;
380 }
381
382 // Adjust NewSize and OldSize or MaxHeapSize to match each other
383 if (NewSize + OldSize > MaxHeapSize) {
384 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
385 // Somebody has set a maximum heap size with the intention that we should not
386 // exceed it. Adjust New/OldSize as necessary.
387 size_t calculated_size = NewSize + OldSize;
388 double shrink_factor = (double) MaxHeapSize / calculated_size;
389 size_t smaller_new_size = align_down((size_t)(NewSize * shrink_factor), _gen_alignment);
390 FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
391 _initial_young_size = NewSize;
392
393 // OldSize is already aligned because above we aligned MaxHeapSize to
394 // _heap_alignment, and we just made sure that NewSize is aligned to
395 // _gen_alignment. In initialize_flags() we verified that _heap_alignment
396 // is a multiple of _gen_alignment.
397 FLAG_SET_ERGO(size_t, OldSize, MaxHeapSize - NewSize);
398 } else {
399 FLAG_SET_ERGO(size_t, MaxHeapSize, align_up(NewSize + OldSize, _heap_alignment));
400 _max_heap_byte_size = MaxHeapSize;
401 }
402 }
403
404 // Update NewSize, if possible, to avoid sizing the young gen too small when only
405 // OldSize is set on the command line.
406 if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) {
407 if (OldSize < _initial_heap_byte_size) {
408 size_t new_size = _initial_heap_byte_size - OldSize;
409 // Need to compare against the flag value for max since _max_young_size
410 // might not have been set yet.
411 if (new_size >= _min_young_size && new_size <= MaxNewSize) {
412 FLAG_SET_ERGO(size_t, NewSize, new_size);
413 _initial_young_size = NewSize;
414 }
415 }
416 }
417
418 always_do_update_barrier = UseConcMarkSweepGC;
419
420 DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
421 }
422
423 // Values set on the command line win over any ergonomically
424 // set command line parameters.
425 // Ergonomic choice of parameters are done before this
426 // method is called. Values for command line parameters such as NewSize
427 // and MaxNewSize feed those ergonomic choices into this method.
428 // This method makes the final generation sizings consistent with
429 // themselves and with overall heap sizings.
430 // In the absence of explicitly set command line flags, policies
431 // such as the use of NewRatio are used to size the generation.
432
433 // Minimum sizes of the generations may be different than
434 // the initial sizes. An inconsistency is permitted here
435 // in the total size that can be specified explicitly by
436 // command line specification of OldSize and NewSize and
437 // also a command line specification of -Xms. Issue a warning
438 // but allow the values to pass.
439 void GenCollectorPolicy::initialize_size_info() {
440 CollectorPolicy::initialize_size_info();
441
442 _initial_young_size = NewSize;
443 _max_young_size = MaxNewSize;
444 _initial_old_size = OldSize;
445
446 // Determine maximum size of the young generation.
447
448 if (FLAG_IS_DEFAULT(MaxNewSize)) {
449 _max_young_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
450 // Bound the maximum size by NewSize below (since it historically
451 // would have been NewSize and because the NewRatio calculation could
452 // yield a size that is too small) and bound it by MaxNewSize above.
453 // Ergonomics plays here by previously calculating the desired
454 // NewSize and MaxNewSize.
455 _max_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize);
456 }
457
458 // Given the maximum young size, determine the initial and
459 // minimum young sizes.
460
461 if (_max_heap_byte_size == _initial_heap_byte_size) {
462 // The maximum and initial heap sizes are the same so the generation's
463 // initial size must be the same as it maximum size. Use NewSize as the
464 // size if set on command line.
465 _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size;
466 _initial_young_size = _max_young_size;
467
468 // Also update the minimum size if min == initial == max.
469 if (_max_heap_byte_size == _min_heap_byte_size) {
470 _min_young_size = _max_young_size;
471 }
472 } else {
473 if (FLAG_IS_CMDLINE(NewSize)) {
474 // If NewSize is set on the command line, we should use it as
475 // the initial size, but make sure it is within the heap bounds.
476 _initial_young_size =
477 MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size));
478 _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size);
479 } else {
480 // For the case where NewSize is not set on the command line, use
481 // NewRatio to size the initial generation size. Use the current
482 // NewSize as the floor, because if NewRatio is overly large, the resulting
483 // size can be too small.
484 _initial_young_size =
485 MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize));
486 }
487 }
488
489 log_trace(gc, heap)("1: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT,
490 _min_young_size, _initial_young_size, _max_young_size);
491
492 // At this point the minimum, initial and maximum sizes
493 // of the overall heap and of the young generation have been determined.
494 // The maximum old size can be determined from the maximum young
495 // and maximum heap size since no explicit flags exist
496 // for setting the old generation maximum.
497 _max_old_size = MAX2(_max_heap_byte_size - _max_young_size, _gen_alignment);
498
499 // If no explicit command line flag has been set for the
500 // old generation size, use what is left.
501 if (!FLAG_IS_CMDLINE(OldSize)) {
502 // The user has not specified any value but the ergonomics
503 // may have chosen a value (which may or may not be consistent
504 // with the overall heap size). In either case make
505 // the minimum, maximum and initial sizes consistent
506 // with the young sizes and the overall heap sizes.
507 _min_old_size = _gen_alignment;
508 _initial_old_size = MIN2(_max_old_size, MAX2(_initial_heap_byte_size - _initial_young_size, _min_old_size));
509 // _max_old_size has already been made consistent above.
510 } else {
511 // OldSize has been explicitly set on the command line. Use it
512 // for the initial size but make sure the minimum allow a young
513 // generation to fit as well.
514 // If the user has explicitly set an OldSize that is inconsistent
515 // with other command line flags, issue a warning.
516 // The generation minimums and the overall heap minimum should
517 // be within one generation alignment.
518 if (_initial_old_size > _max_old_size) {
519 log_warning(gc, ergo)("Inconsistency between maximum heap size and maximum "
520 "generation sizes: using maximum heap = " SIZE_FORMAT
521 ", -XX:OldSize flag is being ignored",
522 _max_heap_byte_size);
523 _initial_old_size = _max_old_size;
524 }
525
526 _min_old_size = MIN2(_initial_old_size, _min_heap_byte_size - _min_young_size);
527 }
528
529 // The initial generation sizes should match the initial heap size,
530 // if not issue a warning and resize the generations. This behavior
531 // differs from JDK8 where the generation sizes have higher priority
532 // than the initial heap size.
533 if ((_initial_old_size + _initial_young_size) != _initial_heap_byte_size) {
534 log_warning(gc, ergo)("Inconsistency between generation sizes and heap size, resizing "
535 "the generations to fit the heap.");
536
537 size_t desired_young_size = _initial_heap_byte_size - _initial_old_size;
538 if (_initial_heap_byte_size < _initial_old_size) {
539 // Old want all memory, use minimum for young and rest for old
540 _initial_young_size = _min_young_size;
541 _initial_old_size = _initial_heap_byte_size - _min_young_size;
542 } else if (desired_young_size > _max_young_size) {
543 // Need to increase both young and old generation
544 _initial_young_size = _max_young_size;
545 _initial_old_size = _initial_heap_byte_size - _max_young_size;
546 } else if (desired_young_size < _min_young_size) {
547 // Need to decrease both young and old generation
548 _initial_young_size = _min_young_size;
549 _initial_old_size = _initial_heap_byte_size - _min_young_size;
550 } else {
551 // The young generation boundaries allow us to only update the
552 // young generation.
553 _initial_young_size = desired_young_size;
554 }
555
556 log_trace(gc, heap)("2: Minimum young " SIZE_FORMAT " Initial young " SIZE_FORMAT " Maximum young " SIZE_FORMAT,
557 _min_young_size, _initial_young_size, _max_young_size);
558 }
559
560 // Write back to flags if necessary.
561 if (NewSize != _initial_young_size) {
562 FLAG_SET_ERGO(size_t, NewSize, _initial_young_size);
563 }
564
565 if (MaxNewSize != _max_young_size) {
566 FLAG_SET_ERGO(size_t, MaxNewSize, _max_young_size);
567 }
568
569 if (OldSize != _initial_old_size) {
570 FLAG_SET_ERGO(size_t, OldSize, _initial_old_size);
571 }
572
573 log_trace(gc, heap)("Minimum old " SIZE_FORMAT " Initial old " SIZE_FORMAT " Maximum old " SIZE_FORMAT,
574 _min_old_size, _initial_old_size, _max_old_size);
575
576 DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
577 }
578
579 //
580 // MarkSweepPolicy methods
581 //
582
583 void MarkSweepPolicy::initialize_alignments() {
584 _space_alignment = _gen_alignment = (size_t)Generation::GenGrain;
585 _heap_alignment = compute_heap_alignment();
586 }
587
588 void MarkSweepPolicy::initialize_generations() {
589 _young_gen_spec = new GenerationSpec(Generation::DefNew, _initial_young_size, _max_young_size, _gen_alignment);
590 _old_gen_spec = new GenerationSpec(Generation::MarkSweepCompact, _initial_old_size, _max_old_size, _gen_alignment);
591 }
592
593 void MarkSweepPolicy::initialize_gc_policy_counters() {
594 // Initialize the policy counters - 2 collectors, 2 generations.
595 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 2);
596 }