1 /*
2 * Copyright (c) 2001, 2021, 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/parallel/objectStartArray.inline.hpp"
27 #include "gc/parallel/parallelArguments.hpp"
28 #include "gc/parallel/parallelScavengeHeap.hpp"
29 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
30 #include "gc/parallel/psCardTable.hpp"
31 #include "gc/parallel/psOldGen.hpp"
32 #include "gc/shared/cardTableBarrierSet.hpp"
33 #include "gc/shared/gcLocker.hpp"
34 #include "gc/shared/spaceDecorator.inline.hpp"
35 #include "logging/log.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/java.hpp"
38 #include "utilities/align.hpp"
39
40 PSOldGen::PSOldGen(ReservedSpace rs, size_t initial_size, size_t min_size,
41 size_t max_size, const char* perf_data_name, int level):
42 _min_gen_size(min_size),
43 _max_gen_size(max_size)
44 {
45 initialize(rs, initial_size, GenAlignment, perf_data_name, level);
46 }
47
48 void PSOldGen::initialize(ReservedSpace rs, size_t initial_size, size_t alignment,
49 const char* perf_data_name, int level) {
50 initialize_virtual_space(rs, initial_size, alignment);
51 initialize_work(perf_data_name, level);
52
53 // The old gen can grow to max_gen_size(). _reserve reflects only
54 // the current maximum that can be committed.
55 assert(_reserved.byte_size() <= max_gen_size(), "Consistency check");
56
57 initialize_performance_counters(perf_data_name, level);
58 }
59
60 void PSOldGen::initialize_virtual_space(ReservedSpace rs,
61 size_t initial_size,
62 size_t alignment) {
63
64 _virtual_space = new PSVirtualSpace(rs, alignment);
65 if (!_virtual_space->expand_by(initial_size)) {
66 vm_exit_during_initialization("Could not reserve enough space for "
67 "object heap");
68 }
69 }
70
71 void PSOldGen::initialize_work(const char* perf_data_name, int level) {
72 //
73 // Basic memory initialization
74 //
75
76 MemRegion limit_reserved((HeapWord*)virtual_space()->low_boundary(),
77 heap_word_size(max_gen_size()));
78 assert(limit_reserved.byte_size() == max_gen_size(),
79 "word vs bytes confusion");
80 //
81 // Object start stuff
82 //
83
84 start_array()->initialize(limit_reserved);
85
86 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
87 (HeapWord*)virtual_space()->high_boundary());
88
89 //
90 // Card table stuff
91 //
92
93 MemRegion cmr((HeapWord*)virtual_space()->low(),
94 (HeapWord*)virtual_space()->high());
95 if (ZapUnusedHeapArea) {
96 // Mangle newly committed space immediately rather than
97 // waiting for the initialization of the space even though
98 // mangling is related to spaces. Doing it here eliminates
99 // the need to carry along information that a complete mangling
100 // (bottom to end) needs to be done.
101 SpaceMangler::mangle_region(cmr);
102 }
103
104 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
105 PSCardTable* ct = heap->card_table();
106 ct->resize_covered_region(cmr);
107
108 // Verify that the start and end of this generation is the start of a card.
109 // If this wasn't true, a single card could span more than one generation,
110 // which would cause problems when we commit/uncommit memory, and when we
111 // clear and dirty cards.
112 guarantee(ct->is_card_aligned(_reserved.start()), "generation must be card aligned");
113 if (_reserved.end() != heap->reserved_region().end()) {
114 // Don't check at the very end of the heap as we'll assert that we're probing off
115 // the end if we try.
116 guarantee(ct->is_card_aligned(_reserved.end()), "generation must be card aligned");
117 }
118
119 //
120 // ObjectSpace stuff
121 //
122
123 _object_space = new MutableSpace(virtual_space()->alignment());
124 object_space()->initialize(cmr,
125 SpaceDecorator::Clear,
126 SpaceDecorator::Mangle,
127 MutableSpace::SetupPages,
128 &ParallelScavengeHeap::heap()->workers());
129
130 // Update the start_array
131 start_array()->set_covered_region(cmr);
132 }
133
134 void PSOldGen::initialize_performance_counters(const char* perf_data_name, int level) {
135 // Generation Counters, generation 'level', 1 subspace
136 _gen_counters = new PSGenerationCounters(perf_data_name, level, 1, min_gen_size(),
137 max_gen_size(), virtual_space());
138 _space_counters = new SpaceCounters(perf_data_name, 0,
139 virtual_space()->reserved_size(),
140 _object_space, _gen_counters);
141 }
142
143 // Assume that the generation has been allocated if its
144 // reserved size is not 0.
145 bool PSOldGen::is_allocated() {
146 return virtual_space()->reserved_size() != 0;
147 }
148
149 size_t PSOldGen::num_iterable_blocks() const {
150 return (object_space()->used_in_bytes() + IterateBlockSize - 1) / IterateBlockSize;
151 }
152
153 void PSOldGen::object_iterate_block(ObjectClosure* cl, size_t block_index) {
154 size_t block_word_size = IterateBlockSize / HeapWordSize;
155 assert((block_word_size % (ObjectStartArray::block_size)) == 0,
156 "Block size not a multiple of start_array block");
157
158 MutableSpace *space = object_space();
159
160 HeapWord* begin = space->bottom() + block_index * block_word_size;
161 HeapWord* end = MIN2(space->top(), begin + block_word_size);
162
163 if (!start_array()->object_starts_in_range(begin, end)) {
164 return;
165 }
166
167 // Get object starting at or reaching into this block.
168 HeapWord* start = start_array()->object_start(begin);
169 if (start < begin) {
170 start += cast_to_oop(start)->size();
171 }
172 assert(start >= begin,
173 "Object address" PTR_FORMAT " must be larger or equal to block address at " PTR_FORMAT,
174 p2i(start), p2i(begin));
175 // Iterate all objects until the end.
176 for (HeapWord* p = start; p < end; p += cast_to_oop(p)->size()) {
177 cl->do_object(cast_to_oop(p));
178 }
179 }
180
181 bool PSOldGen::expand_for_allocate(size_t word_size) {
182 assert(word_size > 0, "allocating zero words?");
183 bool result = true;
184 {
185 MutexLocker x(ExpandHeap_lock);
186 // Avoid "expand storms" by rechecking available space after obtaining
187 // the lock, because another thread may have already made sufficient
188 // space available. If insufficient space available, that will remain
189 // true until we expand, since we have the lock. Other threads may take
190 // the space we need before we can allocate it, regardless of whether we
191 // expand. That's okay, we'll just try expanding again.
192 if (object_space()->needs_expand(word_size)) {
193 result = expand(word_size*HeapWordSize);
194 }
195 }
196 if (GCExpandToAllocateDelayMillis > 0) {
197 os::naked_sleep(GCExpandToAllocateDelayMillis);
198 }
199 return result;
200 }
201
202 bool PSOldGen::expand(size_t bytes) {
203 assert_lock_strong(ExpandHeap_lock);
204 assert_locked_or_safepoint(Heap_lock);
205 assert(bytes > 0, "precondition");
206 const size_t alignment = virtual_space()->alignment();
207 size_t aligned_bytes = align_up(bytes, alignment);
208 size_t aligned_expand_bytes = align_up(MinHeapDeltaBytes, alignment);
209
210 if (UseNUMA) {
211 // With NUMA we use round-robin page allocation for the old gen. Expand by at least
212 // providing a page per lgroup. Alignment is larger or equal to the page size.
213 aligned_expand_bytes = MAX2(aligned_expand_bytes, alignment * os::numa_get_groups_num());
214 }
215 if (aligned_bytes == 0) {
216 // The alignment caused the number of bytes to wrap. A call to expand
217 // implies a best effort to expand by "bytes" but not a guarantee. Align
218 // down to give a best effort. This is likely the most that the generation
219 // can expand since it has some capacity to start with.
220 aligned_bytes = align_down(bytes, alignment);
221 }
222
223 bool success = false;
224 if (aligned_expand_bytes > aligned_bytes) {
225 success = expand_by(aligned_expand_bytes);
226 }
227 if (!success) {
228 success = expand_by(aligned_bytes);
229 }
230 if (!success) {
231 success = expand_to_reserved();
232 }
233
234 if (success && GCLocker::is_active_and_needs_gc()) {
235 log_debug(gc)("Garbage collection disabled, expanded heap instead");
236 }
237 return success;
238 }
239
240 bool PSOldGen::expand_by(size_t bytes) {
241 assert_lock_strong(ExpandHeap_lock);
242 assert_locked_or_safepoint(Heap_lock);
243 assert(bytes > 0, "precondition");
244 bool result = virtual_space()->expand_by(bytes);
245 if (result) {
246 if (ZapUnusedHeapArea) {
247 // We need to mangle the newly expanded area. The memregion spans
248 // end -> new_end, we assume that top -> end is already mangled.
249 // Do the mangling before post_resize() is called because
250 // the space is available for allocation after post_resize();
251 HeapWord* const virtual_space_high = (HeapWord*) virtual_space()->high();
252 assert(object_space()->end() < virtual_space_high,
253 "Should be true before post_resize()");
254 MemRegion mangle_region(object_space()->end(), virtual_space_high);
255 // Note that the object space has not yet been updated to
256 // coincide with the new underlying virtual space.
257 SpaceMangler::mangle_region(mangle_region);
258 }
259 post_resize();
260 if (UsePerfData) {
261 _space_counters->update_capacity();
262 _gen_counters->update_all();
263 }
264 }
265
266 if (result) {
267 size_t new_mem_size = virtual_space()->committed_size();
268 size_t old_mem_size = new_mem_size - bytes;
269 log_debug(gc)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
270 name(), old_mem_size/K, bytes/K, new_mem_size/K);
271 }
272
273 return result;
274 }
275
276 bool PSOldGen::expand_to_reserved() {
277 assert_lock_strong(ExpandHeap_lock);
278 assert_locked_or_safepoint(Heap_lock);
279
280 bool result = false;
281 const size_t remaining_bytes = virtual_space()->uncommitted_size();
282 if (remaining_bytes > 0) {
283 result = expand_by(remaining_bytes);
284 DEBUG_ONLY(if (!result) log_warning(gc)("grow to reserve failed"));
285 }
286 return result;
287 }
288
289 void PSOldGen::shrink(size_t bytes) {
290 assert_lock_strong(ExpandHeap_lock);
291 assert_locked_or_safepoint(Heap_lock);
292
293 size_t size = align_down(bytes, virtual_space()->alignment());
294 if (size > 0) {
295 assert_lock_strong(ExpandHeap_lock);
296 virtual_space()->shrink_by(bytes);
297 post_resize();
298
299 size_t new_mem_size = virtual_space()->committed_size();
300 size_t old_mem_size = new_mem_size + bytes;
301 log_debug(gc)("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
302 name(), old_mem_size/K, bytes/K, new_mem_size/K);
303 }
304 }
305
306 void PSOldGen::resize(size_t desired_free_space) {
307 const size_t alignment = virtual_space()->alignment();
308 const size_t size_before = virtual_space()->committed_size();
309 size_t new_size = used_in_bytes() + desired_free_space;
310 if (new_size < used_in_bytes()) {
311 // Overflowed the addition.
312 new_size = max_gen_size();
313 }
314 // Adjust according to our min and max
315 new_size = clamp(new_size, min_gen_size(), max_gen_size());
316
317 assert(max_gen_size() >= reserved().byte_size(), "max new size problem?");
318 new_size = align_up(new_size, alignment);
319
320 const size_t current_size = capacity_in_bytes();
321
322 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: "
323 "desired free: " SIZE_FORMAT " used: " SIZE_FORMAT
324 " new size: " SIZE_FORMAT " current size " SIZE_FORMAT
325 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
326 desired_free_space, used_in_bytes(), new_size, current_size,
327 max_gen_size(), min_gen_size());
328
329 if (new_size == current_size) {
330 // No change requested
331 return;
332 }
333 if (new_size > current_size) {
334 size_t change_bytes = new_size - current_size;
335 MutexLocker x(ExpandHeap_lock);
336 expand(change_bytes);
337 } else {
338 size_t change_bytes = current_size - new_size;
339 MutexLocker x(ExpandHeap_lock);
340 shrink(change_bytes);
341 }
342
343 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: collection: %d (" SIZE_FORMAT ") -> (" SIZE_FORMAT ") ",
344 ParallelScavengeHeap::heap()->total_collections(),
345 size_before,
346 virtual_space()->committed_size());
347 }
348
349 // NOTE! We need to be careful about resizing. During a GC, multiple
350 // allocators may be active during heap expansion. If we allow the
351 // heap resizing to become visible before we have correctly resized
352 // all heap related data structures, we may cause program failures.
353 void PSOldGen::post_resize() {
354 // First construct a memregion representing the new size
355 MemRegion new_memregion((HeapWord*)virtual_space()->low(),
356 (HeapWord*)virtual_space()->high());
357 size_t new_word_size = new_memregion.word_size();
358
359 start_array()->set_covered_region(new_memregion);
360 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(new_memregion);
361
362 WorkGang* workers = Thread::current()->is_VM_thread() ?
363 &ParallelScavengeHeap::heap()->workers() : NULL;
364
365 // The update of the space's end is done by this call. As that
366 // makes the new space available for concurrent allocation, this
367 // must be the last step when expanding.
368 object_space()->initialize(new_memregion,
369 SpaceDecorator::DontClear,
370 SpaceDecorator::DontMangle,
371 MutableSpace::SetupPages,
372 workers);
373
374 assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()),
375 "Sanity");
376 }
377
378 void PSOldGen::print() const { print_on(tty);}
379 void PSOldGen::print_on(outputStream* st) const {
380 st->print(" %-15s", name());
381 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
382 capacity_in_bytes()/K, used_in_bytes()/K);
383 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
384 p2i(virtual_space()->low_boundary()),
385 p2i(virtual_space()->high()),
386 p2i(virtual_space()->high_boundary()));
387
388 st->print(" object"); object_space()->print_on(st);
389 }
390
391 void PSOldGen::update_counters() {
392 if (UsePerfData) {
393 _space_counters->update_all();
394 _gen_counters->update_all();
395 }
396 }
397
398 void PSOldGen::verify() {
399 object_space()->verify();
400 }
401
402 class VerifyObjectStartArrayClosure : public ObjectClosure {
403 PSOldGen* _old_gen;
404 ObjectStartArray* _start_array;
405
406 public:
407 VerifyObjectStartArrayClosure(PSOldGen* old_gen, ObjectStartArray* start_array) :
408 _old_gen(old_gen), _start_array(start_array) { }
409
410 virtual void do_object(oop obj) {
411 HeapWord* test_addr = cast_from_oop<HeapWord*>(obj) + 1;
412 guarantee(_start_array->object_start(test_addr) == cast_from_oop<HeapWord*>(obj), "ObjectStartArray cannot find start of object");
413 guarantee(_start_array->is_block_allocated(cast_from_oop<HeapWord*>(obj)), "ObjectStartArray missing block allocation");
414 }
415 };
416
417 void PSOldGen::verify_object_start_array() {
418 VerifyObjectStartArrayClosure check( this, &_start_array );
419 object_iterate(&check);
420 }
421
422 #ifndef PRODUCT
423 void PSOldGen::record_spaces_top() {
424 assert(ZapUnusedHeapArea, "Not mangling unused space");
425 object_space()->set_top_for_allocations();
426 }
427 #endif