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 void CollectorPolicy::initialize_flags() {
51 assert(_max_alignment >= _min_alignment,
52 err_msg("max_alignment: " SIZE_FORMAT " less than min_alignment: " SIZE_FORMAT,
53 _max_alignment, _min_alignment));
54 assert(_max_alignment % _min_alignment == 0,
55 err_msg("max_alignment: " SIZE_FORMAT " not aligned by min_alignment: " SIZE_FORMAT,
56 _max_alignment, _min_alignment));
57
58 if (MaxHeapSize < InitialHeapSize) {
59 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
60 }
61
62 MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, _min_alignment);
63 }
64
65 void CollectorPolicy::initialize_size_info() {
66 // User inputs from -mx and ms must be aligned
67 _min_heap_byte_size = align_size_up(Arguments::min_heap_size(), _min_alignment);
68 _initial_heap_byte_size = align_size_up(InitialHeapSize, _min_alignment);
69 _max_heap_byte_size = align_size_up(MaxHeapSize, _max_alignment);
70
71 // Check heap parameter properties
72 if (_initial_heap_byte_size < M) {
73 vm_exit_during_initialization("Too small initial heap");
74 }
75 // Check heap parameter properties
76 if (_min_heap_byte_size < M) {
77 vm_exit_during_initialization("Too small minimum heap");
78 }
79 if (_initial_heap_byte_size <= NewSize) {
80 // make sure there is at least some room in old space
81 vm_exit_during_initialization("Too small initial heap for new size specified");
82 }
83 if (_max_heap_byte_size < _min_heap_byte_size) {
84 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
85 }
86 if (_initial_heap_byte_size < _min_heap_byte_size) {
87 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
88 }
89 if (_max_heap_byte_size < _initial_heap_byte_size) {
90 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
91 }
92
93 if (PrintGCDetails && Verbose) {
94 gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT " Initial heap "
95 SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
96 _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
97 }
98 }
99
100 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
101 bool result = _should_clear_all_soft_refs;
102 set_should_clear_all_soft_refs(false);
103 return result;
104 }
105
106 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
107 int max_covered_regions) {
108 return new CardTableRS(whole_heap, max_covered_regions);
109 }
110
111 void CollectorPolicy::cleared_all_soft_refs() {
112 // If near gc overhear limit, continue to clear SoftRefs. SoftRefs may
113 // have been cleared in the last collection but if the gc overhear
114 // limit continues to be near, SoftRefs should still be cleared.
115 if (size_policy() != NULL) {
116 _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
117 }
118 _all_soft_refs_clear = true;
119 }
120
121 size_t CollectorPolicy::compute_max_alignment() {
122 // The card marking array and the offset arrays for old generations are
123 // committed in os pages as well. Make sure they are entirely full (to
124 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
125 // byte entry and the os page size is 4096, the maximum heap size should
126 // be 512*4096 = 2MB aligned.
127
128 // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable
129 // is supported.
130 // Requirements of any new remembered set implementations must be added here.
131 size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
132
133 // Parallel GC does its own alignment of the generations to avoid requiring a
134 // large page (256M on some platforms) for the permanent generation. The
135 // other collectors should also be updated to do their own alignment and then
136 // this use of lcm() should be removed.
137 if (UseLargePages && !UseParallelGC) {
138 // in presence of large pages we have to make sure that our
139 // alignment is large page aware
140 alignment = lcm(os::large_page_size(), alignment);
141 }
142
143 return alignment;
144 }
145
146 // GenCollectorPolicy methods.
147
148 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
149 return align_size_down_bounded(base_size / (NewRatio + 1), _min_alignment);
150 }
151
152 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
153 size_t maximum_size) {
154 size_t alignment = _min_alignment;
155 size_t max_minus = maximum_size - alignment;
156 return desired_size < max_minus ? desired_size : max_minus;
157 }
158
159
160 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
161 size_t init_promo_size,
162 size_t init_survivor_size) {
163 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
164 _size_policy = new AdaptiveSizePolicy(init_eden_size,
165 init_promo_size,
166 init_survivor_size,
167 max_gc_pause_sec,
168 GCTimeRatio);
169 }
170
171 void GenCollectorPolicy::initialize_flags() {
172 // All sizes must be multiples of the generation granularity.
173 _min_alignment = (uintx) Generation::GenGrain;
174 _max_alignment = compute_max_alignment();
175
176 CollectorPolicy::initialize_flags();
177
178 // All generational heaps have a youngest gen; handle those flags here.
179
180 // Adjust max size parameters
181 if (NewSize > MaxNewSize) {
182 MaxNewSize = NewSize;
183 }
184 NewSize = align_size_down(NewSize, _min_alignment);
185 MaxNewSize = align_size_down(MaxNewSize, _min_alignment);
186
187 // Check validity of heap flags
188 assert(NewSize % _min_alignment == 0, "eden space alignment");
189 assert(MaxNewSize % _min_alignment == 0, "survivor space alignment");
190
191 if (NewSize < 3 * _min_alignment) {
192 // make sure there room for eden and two survivor spaces
193 vm_exit_during_initialization("Too small new size specified");
194 }
195
196 if (SurvivorRatio < 1 || NewRatio < 1) {
197 vm_exit_during_initialization("Invalid young gen ratio specified");
198 }
199 }
200
201 void TwoGenerationCollectorPolicy::initialize_flags() {
202 GenCollectorPolicy::initialize_flags();
203
204 OldSize = align_size_down(OldSize, _min_alignment);
205
206 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(NewSize)) {
207 // NewRatio will be used later to set the young generation size so we use
208 // it to calculate how big the heap should be based on the requested OldSize
209 // and NewRatio.
210 assert(NewRatio > 0, "NewRatio should have been set up earlier");
211 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
212
213 calculated_heapsize = align_size_up(calculated_heapsize, _max_alignment);
214 MaxHeapSize = calculated_heapsize;
215 InitialHeapSize = calculated_heapsize;
216 }
217 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment);
218
219 // adjust max heap size if necessary
220 if (NewSize + OldSize > MaxHeapSize) {
221 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
222 // somebody set a maximum heap size with the intention that we should not
223 // exceed it. Adjust New/OldSize as necessary.
224 uintx calculated_size = NewSize + OldSize;
225 double shrink_factor = (double) MaxHeapSize / calculated_size;
226 // align
227 NewSize = align_size_down((uintx) (NewSize * shrink_factor), _min_alignment);
228 // OldSize is already aligned because above we aligned MaxHeapSize to
229 // _max_alignment, and we just made sure that NewSize is aligned to
230 // _min_alignment. In initialize_flags() we verified that _max_alignment
231 // is a multiple of _min_alignment.
232 OldSize = MaxHeapSize - NewSize;
233 } else {
234 MaxHeapSize = NewSize + OldSize;
235 }
236 }
237 // need to do this again
238 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment);
239
240 // adjust max heap size if necessary
241 if (NewSize + OldSize > MaxHeapSize) {
242 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
243 // somebody set a maximum heap size with the intention that we should not
244 // exceed it. Adjust New/OldSize as necessary.
245 uintx calculated_size = NewSize + OldSize;
246 double shrink_factor = (double) MaxHeapSize / calculated_size;
247 // align
248 NewSize = align_size_down((uintx) (NewSize * shrink_factor), _min_alignment);
249 // OldSize is already aligned because above we aligned MaxHeapSize to
250 // _max_alignment, and we just made sure that NewSize is aligned to
251 // _min_alignment. In initialize_flags() we verified that _max_alignment
252 // is a multiple of _min_alignment.
253 OldSize = MaxHeapSize - NewSize;
254 } else {
255 MaxHeapSize = NewSize + OldSize;
256 }
257 }
258 // need to do this again
259 MaxHeapSize = align_size_up(MaxHeapSize, _max_alignment);
260
261 always_do_update_barrier = UseConcMarkSweepGC;
262
263 // Check validity of heap flags
264 assert(OldSize % _min_alignment == 0, "old space alignment");
265 assert(MaxHeapSize % _max_alignment == 0, "maximum heap alignment");
266 }
267
268 // Values set on the command line win over any ergonomically
269 // set command line parameters.
270 // Ergonomic choice of parameters are done before this
271 // method is called. Values for command line parameters such as NewSize
272 // and MaxNewSize feed those ergonomic choices into this method.
273 // This method makes the final generation sizings consistent with
274 // themselves and with overall heap sizings.
275 // In the absence of explicitly set command line flags, policies
276 // such as the use of NewRatio are used to size the generation.
277 void GenCollectorPolicy::initialize_size_info() {
278 CollectorPolicy::initialize_size_info();
279
280 // _min_alignment is used for alignment within a generation.
281 // There is additional alignment done down stream for some
282 // collectors that sometimes causes unwanted rounding up of
283 // generations sizes.
284
285 // Determine maximum size of gen0
286
287 size_t max_new_size = 0;
288 if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) {
289 if (MaxNewSize < _min_alignment) {
290 max_new_size = _min_alignment;
291 }
292 if (MaxNewSize >= _max_heap_byte_size) {
293 max_new_size = align_size_down(_max_heap_byte_size - _min_alignment,
294 _min_alignment);
295 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or "
296 "greater than the entire heap (" SIZE_FORMAT "k). A "
297 "new generation size of " SIZE_FORMAT "k will be used.",
298 MaxNewSize/K, _max_heap_byte_size/K, max_new_size/K);
299 } else {
300 max_new_size = align_size_down(MaxNewSize, _min_alignment);
301 }
302
303 // The case for FLAG_IS_ERGO(MaxNewSize) could be treated
304 // specially at this point to just use an ergonomically set
305 // MaxNewSize to set max_new_size. For cases with small
306 // heaps such a policy often did not work because the MaxNewSize
307 // was larger than the entire heap. The interpretation given
308 // to ergonomically set flags is that the flags are set
309 // by different collectors for their own special needs but
310 // are not allowed to badly shape the heap. This allows the
311 // different collectors to decide what's best for themselves
312 // without having to factor in the overall heap shape. It
313 // can be the case in the future that the collectors would
314 // only make "wise" ergonomics choices and this policy could
315 // just accept those choices. The choices currently made are
316 // not always "wise".
317 } else {
318 max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
319 // Bound the maximum size by NewSize below (since it historically
320 // would have been NewSize and because the NewRatio calculation could
321 // yield a size that is too small) and bound it by MaxNewSize above.
322 // Ergonomics plays here by previously calculating the desired
323 // NewSize and MaxNewSize.
324 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
325 }
326 assert(max_new_size > 0, "All paths should set max_new_size");
327
328 // Given the maximum gen0 size, determine the initial and
329 // minimum gen0 sizes.
330
331 if (_max_heap_byte_size == _min_heap_byte_size) {
332 // The maximum and minimum heap sizes are the same so
333 // the generations minimum and initial must be the
334 // same as its maximum.
335 _min_gen0_size = max_new_size;
336 _initial_gen0_size = max_new_size;
365 _max_gen0_size = max_new_size;
366
367 // At this point the desirable initial and minimum sizes have been
368 // determined without regard to the maximum sizes.
369
370 // Bound the sizes by the corresponding overall heap sizes.
371 _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size);
372 _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size);
373 _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size);
374
375 // At this point all three sizes have been checked against the
376 // maximum sizes but have not been checked for consistency
377 // among the three.
378
379 // Final check min <= initial <= max
380 _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size);
381 _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size);
382 _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size);
383 }
384
385 if (PrintGCDetails && Verbose) {
386 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
387 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
388 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
389 }
390 }
391
392 // Call this method during the sizing of the gen1 to make
393 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has
394 // the most freedom in sizing because it is done before the
395 // policy for gen1 is applied. Once gen1 policies have been applied,
396 // there may be conflicts in the shape of the heap and this method
397 // is used to make the needed adjustments. The application of the
398 // policies could be more sophisticated (iterative for example) but
399 // keeping it simple also seems a worthwhile goal.
400 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
401 size_t* gen1_size_ptr,
402 const size_t heap_size,
403 const size_t min_gen1_size) {
404 bool result = false;
405
406 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
407 if ((heap_size < (*gen0_size_ptr + min_gen1_size)) &&
408 (heap_size >= min_gen1_size + _min_alignment)) {
409 // Adjust gen0 down to accommodate min_gen1_size
410 *gen0_size_ptr = align_size_down_bounded(heap_size - min_gen1_size, _min_alignment);
411 assert(*gen0_size_ptr > 0, "Min gen0 is too large");
412 result = true;
413 } else {
414 *gen1_size_ptr = align_size_down_bounded(heap_size - *gen0_size_ptr, _min_alignment);
415 }
416 }
417 return result;
418 }
419
420 // Minimum sizes of the generations may be different than
421 // the initial sizes. An inconsistently is permitted here
422 // in the total size that can be specified explicitly by
423 // command line specification of OldSize and NewSize and
424 // also a command line specification of -Xms. Issue a warning
425 // but allow the values to pass.
426
427 void TwoGenerationCollectorPolicy::initialize_size_info() {
428 GenCollectorPolicy::initialize_size_info();
429
430 // At this point the minimum, initial and maximum sizes
431 // of the overall heap and of gen0 have been determined.
432 // The maximum gen1 size can be determined from the maximum gen0
433 // and maximum heap size since no explicit flags exits
434 // for setting the gen1 maximum.
435 _max_gen1_size = _max_heap_byte_size - _max_gen0_size;
436 _max_gen1_size =
437 MAX2((uintx)align_size_down(_max_gen1_size, _min_alignment), _min_alignment);
438 // If no explicit command line flag has been set for the
439 // gen1 size, use what is left for gen1.
440 if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) {
441 // The user has not specified any value or ergonomics
442 // has chosen a value (which may or may not be consistent
443 // with the overall heap size). In either case make
444 // the minimum, maximum and initial sizes consistent
445 // with the gen0 sizes and the overall heap sizes.
446 assert(_min_heap_byte_size > _min_gen0_size,
447 "gen0 has an unexpected minimum size");
448 _min_gen1_size = _min_heap_byte_size - _min_gen0_size;
449 _min_gen1_size =
450 MAX2((uintx)align_size_down(_min_gen1_size, _min_alignment), _min_alignment);
451 _initial_gen1_size = _initial_heap_byte_size - _initial_gen0_size;
452 _initial_gen1_size =
453 MAX2((uintx)align_size_down(_initial_gen1_size, _min_alignment), _min_alignment);
454 } else {
455 // It's been explicitly set on the command line. Use the
456 // OldSize and then determine the consequences.
457 _min_gen1_size = OldSize;
458 _initial_gen1_size = OldSize;
459
460 // If the user has explicitly set an OldSize that is inconsistent
461 // with other command line flags, issue a warning.
462 // The generation minimums and the overall heap mimimum should
463 // be within one heap alignment.
464 if ((_min_gen1_size + _min_gen0_size + _min_alignment) < _min_heap_byte_size) {
465 warning("Inconsistency between minimum heap size and minimum "
466 "generation sizes: using minimum heap = " SIZE_FORMAT,
467 _min_heap_byte_size);
468 }
469 if (OldSize > _max_gen1_size) {
470 warning("Inconsistency between maximum heap size and maximum "
471 "generation sizes: using maximum heap = " SIZE_FORMAT
472 " -XX:OldSize flag is being ignored",
473 _max_heap_byte_size);
474 }
475 // If there is an inconsistency between the OldSize and the minimum and/or
476 // initial size of gen0, since OldSize was explicitly set, OldSize wins.
477 if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
478 _min_heap_byte_size, OldSize)) {
479 if (PrintGCDetails && Verbose) {
480 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
481 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
482 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
483 }
484 }
485 // Initial size
486 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
487 _initial_heap_byte_size, OldSize)) {
488 if (PrintGCDetails && Verbose) {
489 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
490 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
491 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
492 }
493 }
494 }
495 // Enforce the maximum gen1 size.
496 _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size);
497
498 // Check that min gen1 <= initial gen1 <= max gen1
499 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size);
500 _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size);
501
502 if (PrintGCDetails && Verbose) {
503 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 "
504 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT,
505 _min_gen1_size, _initial_gen1_size, _max_gen1_size);
506 }
507 }
508
509 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
510 bool is_tlab,
511 bool* gc_overhead_limit_was_exceeded) {
512 GenCollectedHeap *gch = GenCollectedHeap::heap();
513
514 debug_only(gch->check_for_valid_allocation_state());
515 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
516
517 // In general gc_overhead_limit_was_exceeded should be false so
518 // set it so here and reset it to true only if the gc time
519 // limit is being exceeded as checked below.
520 *gc_overhead_limit_was_exceeded = false;
521
522 HeapWord* result = NULL;
523
524 // Loop until the allocation is satisified,
525 // or unsatisfied after GC.
526 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
809 // Return true if any of the following is true:
810 // . the allocation won't fit into the current young gen heap
811 // . gc locker is occupied (jni critical section)
812 // . heap memory is tight -- the most recent previous collection
813 // was a full collection because a partial collection (would
814 // have) failed and is likely to fail again
815 bool GenCollectorPolicy::should_try_older_generation_allocation(
816 size_t word_size) const {
817 GenCollectedHeap* gch = GenCollectedHeap::heap();
818 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
819 return (word_size > heap_word_size(gen0_capacity))
820 || GC_locker::is_active_and_needs_gc()
821 || gch->incremental_collection_failed();
822 }
823
824
825 //
826 // MarkSweepPolicy methods
827 //
828
829 MarkSweepPolicy::MarkSweepPolicy() {
830 initialize_all();
831 }
832
833 void MarkSweepPolicy::initialize_generations() {
834 _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL);
835 if (_generations == NULL) {
836 vm_exit_during_initialization("Unable to allocate gen spec");
837 }
838
839 if (UseParNewGC) {
840 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
841 } else {
842 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
843 }
844 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
845
846 if (_generations[0] == NULL || _generations[1] == NULL) {
847 vm_exit_during_initialization("Unable to allocate gen spec");
848 }
849 }
850
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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 // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable
182 // is supported.
183 // Requirements of any new remembered set implementations must be added here.
184 size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
185
186 // Parallel GC does its own alignment of the generations to avoid requiring a
187 // large page (256M on some platforms) for the permanent generation. The
188 // other collectors should also be updated to do their own alignment and then
189 // this use of lcm() should be removed.
190 if (UseLargePages && !UseParallelGC) {
191 // in presence of large pages we have to make sure that our
192 // alignment is large page aware
193 alignment = lcm(os::large_page_size(), alignment);
194 }
195
196 return alignment;
197 }
198
199 // GenCollectorPolicy methods.
200
201 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
202 return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
203 }
204
205 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
206 size_t maximum_size) {
207 size_t max_minus = maximum_size - _gen_alignment;
208 return desired_size < max_minus ? desired_size : max_minus;
209 }
210
211
212 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
213 size_t init_promo_size,
214 size_t init_survivor_size) {
215 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
216 _size_policy = new AdaptiveSizePolicy(init_eden_size,
217 init_promo_size,
218 init_survivor_size,
219 max_gc_pause_sec,
220 GCTimeRatio);
221 }
222
223 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
224 // The young generation must be aligned and have room for eden + two survivors
225 return align_size_up(3 * _space_alignment, _gen_alignment);
226 }
227
228 #ifdef ASSERT
229 void GenCollectorPolicy::assert_flags() {
230 CollectorPolicy::assert_flags();
231 assert(NewSize >= _min_gen0_size, "Ergonomics decided on a too small young gen size");
232 assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
233 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
234 assert(NewSize % _gen_alignment == 0, "NewSize alignment");
235 assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
236 }
237
238 void TwoGenerationCollectorPolicy::assert_flags() {
239 GenCollectorPolicy::assert_flags();
240 assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
241 assert(OldSize % _gen_alignment == 0, "OldSize alignment");
242 }
243
244 void GenCollectorPolicy::assert_size_info() {
245 CollectorPolicy::assert_size_info();
246 // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
247 assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
248 assert(NewSize == _initial_gen0_size, "Discrepancy between NewSize flag and local storage");
249 assert(MaxNewSize == _max_gen0_size, "Discrepancy between MaxNewSize flag and local storage");
250 assert(_min_gen0_size <= _initial_gen0_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
251 assert(_initial_gen0_size <= _max_gen0_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
252 assert(_min_gen0_size % _gen_alignment == 0, "_min_gen0_size alignment");
253 assert(_initial_gen0_size % _gen_alignment == 0, "_initial_gen0_size alignment");
254 assert(_max_gen0_size % _gen_alignment == 0, "_max_gen0_size alignment");
255 }
256
257 void TwoGenerationCollectorPolicy::assert_size_info() {
258 GenCollectorPolicy::assert_size_info();
259 assert(OldSize == _initial_gen1_size, "Discrepancy between OldSize flag and local storage");
260 assert(_min_gen1_size <= _initial_gen1_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
261 assert(_initial_gen1_size <= _max_gen1_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
262 assert(_max_gen1_size % _gen_alignment == 0, "_max_gen1_size alignment");
263 assert(_initial_gen1_size % _gen_alignment == 0, "_initial_gen1_size alignment");
264 assert(_max_heap_byte_size <= (_max_gen0_size + _max_gen1_size), "Total maximum heap sizes must be sum of generation maximum sizes");
265 }
266 #endif // ASSERT
267
268 void GenCollectorPolicy::initialize_flags() {
269 CollectorPolicy::initialize_flags();
270
271 assert(_gen_alignment != 0, "Generation alignment not set up properly");
272 assert(_heap_alignment >= _gen_alignment,
273 err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
274 _heap_alignment, _gen_alignment));
275 assert(_gen_alignment % _space_alignment == 0,
276 err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
277 _gen_alignment, _space_alignment));
278 assert(_heap_alignment % _gen_alignment == 0,
279 err_msg("heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
280 _heap_alignment, _gen_alignment));
281
282 // All generational heaps have a youngest gen; handle those flags here
283
284 // Make sure the heap is large enough for two generations
285 uintx smallest_new_size = young_gen_size_lower_bound();
286 uintx smallest_heap_size = align_size_up(smallest_new_size + align_size_up(_space_alignment, _gen_alignment),
287 _heap_alignment);
288 if (MaxHeapSize < smallest_heap_size) {
289 FLAG_SET_ERGO(uintx, MaxHeapSize, smallest_heap_size);
290 _max_heap_byte_size = MaxHeapSize;
291 }
292 // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
293 if (_min_heap_byte_size < smallest_heap_size) {
294 _min_heap_byte_size = smallest_heap_size;
295 if (InitialHeapSize < _min_heap_byte_size) {
296 FLAG_SET_ERGO(uintx, InitialHeapSize, smallest_heap_size);
297 _initial_heap_byte_size = smallest_heap_size;
298 }
299 }
300
301 // Now take the actual NewSize into account. We will silently increase NewSize
302 // if the user specified a smaller value.
303 smallest_new_size = MAX2(smallest_new_size, (uintx)align_size_down(NewSize, _gen_alignment));
304 if (smallest_new_size != NewSize) {
305 FLAG_SET_ERGO(uintx, NewSize, smallest_new_size);
306 }
307 _initial_gen0_size = NewSize;
308
309 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
310 uintx min_new_size = MAX2(_gen_alignment, _min_gen0_size);
311
312 if (MaxNewSize >= MaxHeapSize) {
313 // Make sure there is room for an old generation
314 uintx smaller_max_new_size = MaxHeapSize - _gen_alignment;
315 if (FLAG_IS_CMDLINE(MaxNewSize)) {
316 warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
317 "heap (" SIZE_FORMAT "k). A new max generation size of " SIZE_FORMAT "k will be used.",
318 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
319 }
320 FLAG_SET_ERGO(uintx, MaxNewSize, smaller_max_new_size);
321 if (NewSize > MaxNewSize) {
322 FLAG_SET_ERGO(uintx, NewSize, MaxNewSize);
323 _initial_gen0_size = NewSize;
324 }
325 } else if (MaxNewSize < min_new_size) {
326 FLAG_SET_ERGO(uintx, MaxNewSize, min_new_size);
327 } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) {
328 FLAG_SET_ERGO(uintx, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment));
329 }
330 _max_gen0_size = MaxNewSize;
331 }
332
333 if (NewSize > MaxNewSize) {
334 // At this point this should only happen if the user specifies a large NewSize and/or
335 // a small (but not too small) MaxNewSize.
336 if (FLAG_IS_CMDLINE(MaxNewSize)) {
337 warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
338 "A new max generation size of " SIZE_FORMAT "k will be used.",
339 NewSize/K, MaxNewSize/K, NewSize/K);
340 }
341 FLAG_SET_ERGO(uintx, MaxNewSize, NewSize);
342 _max_gen0_size = MaxNewSize;
343 }
344
345 if (SurvivorRatio < 1 || NewRatio < 1) {
346 vm_exit_during_initialization("Invalid young gen ratio specified");
347 }
348
349 DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
350 }
351
352 void TwoGenerationCollectorPolicy::initialize_flags() {
353 GenCollectorPolicy::initialize_flags();
354
355 if (!is_size_aligned(OldSize, _gen_alignment)) {
356 FLAG_SET_ERGO(uintx, OldSize, align_size_down(OldSize, _gen_alignment));
357 }
358
359 if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
360 // NewRatio will be used later to set the young generation size so we use
361 // it to calculate how big the heap should be based on the requested OldSize
362 // and NewRatio.
363 assert(NewRatio > 0, "NewRatio should have been set up earlier");
364 size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
365
366 calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment);
367 FLAG_SET_ERGO(uintx, MaxHeapSize, calculated_heapsize);
368 _max_heap_byte_size = MaxHeapSize;
369 FLAG_SET_ERGO(uintx, InitialHeapSize, calculated_heapsize);
370 _initial_heap_byte_size = InitialHeapSize;
371 }
372
373 // adjust max heap size if necessary
374 if (NewSize + OldSize > MaxHeapSize) {
375 if (_max_heap_size_cmdline) {
376 // somebody set a maximum heap size with the intention that we should not
377 // exceed it. Adjust New/OldSize as necessary.
378 uintx calculated_size = NewSize + OldSize;
379 double shrink_factor = (double) MaxHeapSize / calculated_size;
380 uintx smaller_new_size = align_size_down((uintx)(NewSize * shrink_factor), _gen_alignment);
381 FLAG_SET_ERGO(uintx, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
382 _initial_gen0_size = NewSize;
383
384 // OldSize is already aligned because above we aligned MaxHeapSize to
385 // _heap_alignment, and we just made sure that NewSize is aligned to
386 // _gen_alignment. In initialize_flags() we verified that _heap_alignment
387 // is a multiple of _gen_alignment.
388 FLAG_SET_ERGO(uintx, OldSize, MaxHeapSize - NewSize);
389 } else {
390 FLAG_SET_ERGO(uintx, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment));
391 _max_heap_byte_size = MaxHeapSize;
392 }
393 }
394
395 always_do_update_barrier = UseConcMarkSweepGC;
396
397 DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_flags();)
398 }
399
400 // Values set on the command line win over any ergonomically
401 // set command line parameters.
402 // Ergonomic choice of parameters are done before this
403 // method is called. Values for command line parameters such as NewSize
404 // and MaxNewSize feed those ergonomic choices into this method.
405 // This method makes the final generation sizings consistent with
406 // themselves and with overall heap sizings.
407 // In the absence of explicitly set command line flags, policies
408 // such as the use of NewRatio are used to size the generation.
409 void GenCollectorPolicy::initialize_size_info() {
410 CollectorPolicy::initialize_size_info();
411
412 // _space_alignment is used for alignment within a generation.
413 // There is additional alignment done down stream for some
414 // collectors that sometimes causes unwanted rounding up of
415 // generations sizes.
416
417 // Determine maximum size of gen0
418
419 size_t max_new_size = 0;
420 if (!FLAG_IS_DEFAULT(MaxNewSize)) {
421 max_new_size = MaxNewSize;
422 } else {
423 max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
424 // Bound the maximum size by NewSize below (since it historically
425 // would have been NewSize and because the NewRatio calculation could
426 // yield a size that is too small) and bound it by MaxNewSize above.
427 // Ergonomics plays here by previously calculating the desired
428 // NewSize and MaxNewSize.
429 max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
430 }
431 assert(max_new_size > 0, "All paths should set max_new_size");
432
433 // Given the maximum gen0 size, determine the initial and
434 // minimum gen0 sizes.
435
436 if (_max_heap_byte_size == _min_heap_byte_size) {
437 // The maximum and minimum heap sizes are the same so
438 // the generations minimum and initial must be the
439 // same as its maximum.
440 _min_gen0_size = max_new_size;
441 _initial_gen0_size = max_new_size;
470 _max_gen0_size = max_new_size;
471
472 // At this point the desirable initial and minimum sizes have been
473 // determined without regard to the maximum sizes.
474
475 // Bound the sizes by the corresponding overall heap sizes.
476 _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size);
477 _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size);
478 _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size);
479
480 // At this point all three sizes have been checked against the
481 // maximum sizes but have not been checked for consistency
482 // among the three.
483
484 // Final check min <= initial <= max
485 _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size);
486 _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size);
487 _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size);
488 }
489
490 // Write back to flags if necessary
491 if (NewSize != _initial_gen0_size) {
492 FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);
493 }
494
495 if (MaxNewSize != _max_gen0_size) {
496 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
497 }
498
499 if (PrintGCDetails && Verbose) {
500 gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
501 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
502 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
503 }
504
505 DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
506 }
507
508 // Call this method during the sizing of the gen1 to make
509 // adjustments to gen0 because of gen1 sizing policy. gen0 initially has
510 // the most freedom in sizing because it is done before the
511 // policy for gen1 is applied. Once gen1 policies have been applied,
512 // there may be conflicts in the shape of the heap and this method
513 // is used to make the needed adjustments. The application of the
514 // policies could be more sophisticated (iterative for example) but
515 // keeping it simple also seems a worthwhile goal.
516 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
517 size_t* gen1_size_ptr,
518 const size_t heap_size,
519 const size_t min_gen1_size) {
520 bool result = false;
521
522 if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
523 uintx smallest_new_size = young_gen_size_lower_bound();
524 if ((heap_size < (*gen0_size_ptr + min_gen1_size)) &&
525 (heap_size >= min_gen1_size + smallest_new_size)) {
526 // Adjust gen0 down to accommodate min_gen1_size
527 *gen0_size_ptr = align_size_down_bounded(heap_size - min_gen1_size, _gen_alignment);
528 assert(*gen0_size_ptr > 0, "Min gen0 is too large");
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 inconsistently 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 exits
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 // It's 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 mimimum 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,
590 _min_heap_byte_size, _min_gen1_size)) {
591 if (PrintGCDetails && Verbose) {
592 gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
593 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
594 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
595 }
596 }
597 // Initial size
598 if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
599 _initial_heap_byte_size, _initial_gen1_size)) {
600 if (PrintGCDetails && Verbose) {
601 gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT " Initial gen0 "
602 SIZE_FORMAT " Maximum gen0 " SIZE_FORMAT,
603 _min_gen0_size, _initial_gen0_size, _max_gen0_size);
604 }
605 }
606 }
607 // Enforce the maximum gen1 size.
608 _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size);
609
610 // Check that min gen1 <= initial gen1 <= max gen1
611 _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size);
612 _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size);
613
614 // Write back to flags if necessary
615 if (NewSize != _initial_gen0_size) {
616 FLAG_SET_ERGO(uintx, NewSize, _max_gen0_size);
617 }
618
619 if (MaxNewSize != _max_gen0_size) {
620 FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);
621 }
622
623 if (OldSize != _initial_gen1_size) {
624 FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);
625 }
626
627 if (PrintGCDetails && Verbose) {
628 gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT " Initial gen1 "
629 SIZE_FORMAT " Maximum gen1 " SIZE_FORMAT,
630 _min_gen1_size, _initial_gen1_size, _max_gen1_size);
631 }
632
633 DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_size_info();)
634 }
635
636 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
637 bool is_tlab,
638 bool* gc_overhead_limit_was_exceeded) {
639 GenCollectedHeap *gch = GenCollectedHeap::heap();
640
641 debug_only(gch->check_for_valid_allocation_state());
642 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
643
644 // In general gc_overhead_limit_was_exceeded should be false so
645 // set it so here and reset it to true only if the gc time
646 // limit is being exceeded as checked below.
647 *gc_overhead_limit_was_exceeded = false;
648
649 HeapWord* result = NULL;
650
651 // Loop until the allocation is satisified,
652 // or unsatisfied after GC.
653 for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
936 // Return true if any of the following is true:
937 // . the allocation won't fit into the current young gen heap
938 // . gc locker is occupied (jni critical section)
939 // . heap memory is tight -- the most recent previous collection
940 // was a full collection because a partial collection (would
941 // have) failed and is likely to fail again
942 bool GenCollectorPolicy::should_try_older_generation_allocation(
943 size_t word_size) const {
944 GenCollectedHeap* gch = GenCollectedHeap::heap();
945 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
946 return (word_size > heap_word_size(gen0_capacity))
947 || GC_locker::is_active_and_needs_gc()
948 || gch->incremental_collection_failed();
949 }
950
951
952 //
953 // MarkSweepPolicy methods
954 //
955
956 void MarkSweepPolicy::initialize_alignments() {
957 _space_alignment = _gen_alignment = (uintx)Generation::GenGrain;
958 _heap_alignment = compute_heap_alignment();
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
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