1 /*
2 * Copyright (c) 2001, 2023, 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 initialize_performance_counters(perf_data_name, level);
54 }
55
56 void PSOldGen::initialize_virtual_space(ReservedSpace rs,
57 size_t initial_size,
58 size_t alignment) {
59
60 _virtual_space = new PSVirtualSpace(rs, alignment);
61 if (!_virtual_space->expand_by(initial_size)) {
62 vm_exit_during_initialization("Could not reserve enough space for "
63 "object heap");
64 }
65 }
66
67 void PSOldGen::initialize_work(const char* perf_data_name, int level) {
68 MemRegion const reserved_mr = reserved();
69 assert(reserved_mr.byte_size() == max_gen_size(), "invariant");
70
71 // Object start stuff: for all reserved memory
72 start_array()->initialize(reserved_mr);
73
74 // Card table stuff: for all committed memory
75 MemRegion committed_mr((HeapWord*)virtual_space()->low(),
76 (HeapWord*)virtual_space()->high());
77
78 if (ZapUnusedHeapArea) {
79 // Mangle newly committed space immediately rather than
80 // waiting for the initialization of the space even though
81 // mangling is related to spaces. Doing it here eliminates
82 // the need to carry along information that a complete mangling
83 // (bottom to end) needs to be done.
84 SpaceMangler::mangle_region(committed_mr);
85 }
86
87 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
88 PSCardTable* ct = heap->card_table();
89 ct->resize_covered_region(committed_mr);
90
91 // Verify that the start and end of this generation is the start of a card.
92 // If this wasn't true, a single card could span more than one generation,
93 // which would cause problems when we commit/uncommit memory, and when we
94 // clear and dirty cards.
95 guarantee(ct->is_card_aligned(reserved_mr.start()), "generation must be card aligned");
96 // Check the heap layout documented at `class ParallelScavengeHeap`.
97 assert(reserved_mr.end() != heap->reserved_region().end(), "invariant");
98 guarantee(ct->is_card_aligned(reserved_mr.end()), "generation must be card aligned");
99
100 //
101 // ObjectSpace stuff
102 //
103
104 _object_space = new MutableSpace(virtual_space()->alignment());
105 object_space()->initialize(committed_mr,
106 SpaceDecorator::Clear,
107 SpaceDecorator::Mangle,
108 MutableSpace::SetupPages,
109 &ParallelScavengeHeap::heap()->workers());
110
111 // Update the start_array
112 start_array()->set_covered_region(committed_mr);
113 }
114
115 void PSOldGen::initialize_performance_counters(const char* perf_data_name, int level) {
116 // Generation Counters, generation 'level', 1 subspace
117 _gen_counters = new PSGenerationCounters(perf_data_name, level, 1, min_gen_size(),
118 max_gen_size(), virtual_space());
119 _space_counters = new SpaceCounters(perf_data_name, 0,
120 virtual_space()->reserved_size(),
121 _object_space, _gen_counters);
122 }
123
124 // Assume that the generation has been allocated if its
125 // reserved size is not 0.
126 bool PSOldGen::is_allocated() {
127 return virtual_space()->reserved_size() != 0;
128 }
129
130 size_t PSOldGen::num_iterable_blocks() const {
131 return (object_space()->used_in_bytes() + IterateBlockSize - 1) / IterateBlockSize;
132 }
133
134 void PSOldGen::object_iterate_block(ObjectClosure* cl, size_t block_index) {
135 size_t block_word_size = IterateBlockSize / HeapWordSize;
136 assert((block_word_size % (ObjectStartArray::card_size())) == 0,
137 "Block size not a multiple of start_array block");
138
139 MutableSpace *space = object_space();
140
141 HeapWord* begin = space->bottom() + block_index * block_word_size;
142 HeapWord* end = MIN2(space->top(), begin + block_word_size);
143
144 if (!start_array()->object_starts_in_range(begin, end)) {
145 return;
146 }
147
148 // Get object starting at or reaching into this block.
149 HeapWord* start = start_array()->object_start(begin);
150 if (start < begin) {
151 start += cast_to_oop(start)->size();
152 }
153 assert(start >= begin,
154 "Object address" PTR_FORMAT " must be larger or equal to block address at " PTR_FORMAT,
155 p2i(start), p2i(begin));
156 // Iterate all objects until the end.
157 for (HeapWord* p = start; p < end; p += cast_to_oop(p)->size()) {
158 cl->do_object(cast_to_oop(p));
159 }
160 }
161
162 bool PSOldGen::expand_for_allocate(size_t word_size) {
163 assert(word_size > 0, "allocating zero words?");
164 bool result = true;
165 {
166 MutexLocker x(PSOldGenExpand_lock);
167 // Avoid "expand storms" by rechecking available space after obtaining
168 // the lock, because another thread may have already made sufficient
169 // space available. If insufficient space available, that will remain
170 // true until we expand, since we have the lock. Other threads may take
171 // the space we need before we can allocate it, regardless of whether we
172 // expand. That's okay, we'll just try expanding again.
173 if (object_space()->needs_expand(word_size)) {
174 result = expand(word_size*HeapWordSize);
175 }
176 }
177 if (GCExpandToAllocateDelayMillis > 0) {
178 os::naked_sleep(GCExpandToAllocateDelayMillis);
179 }
180 return result;
181 }
182
183 bool PSOldGen::expand(size_t bytes) {
184 assert_lock_strong(PSOldGenExpand_lock);
185 assert_locked_or_safepoint(Heap_lock);
186 assert(bytes > 0, "precondition");
187 const size_t alignment = virtual_space()->alignment();
188 size_t aligned_bytes = align_up(bytes, alignment);
189 size_t aligned_expand_bytes = align_up(MinHeapDeltaBytes, alignment);
190
191 if (UseNUMA) {
192 // With NUMA we use round-robin page allocation for the old gen. Expand by at least
193 // providing a page per lgroup. Alignment is larger or equal to the page size.
194 aligned_expand_bytes = MAX2(aligned_expand_bytes, alignment * os::numa_get_groups_num());
195 }
196 if (aligned_bytes == 0) {
197 // The alignment caused the number of bytes to wrap. A call to expand
198 // implies a best effort to expand by "bytes" but not a guarantee. Align
199 // down to give a best effort. This is likely the most that the generation
200 // can expand since it has some capacity to start with.
201 aligned_bytes = align_down(bytes, alignment);
202 }
203
204 bool success = false;
205 if (aligned_expand_bytes > aligned_bytes) {
206 success = expand_by(aligned_expand_bytes);
207 }
208 if (!success) {
209 success = expand_by(aligned_bytes);
210 }
211 if (!success) {
212 success = expand_to_reserved();
213 }
214
215 if (success && GCLocker::is_active_and_needs_gc()) {
216 log_debug(gc)("Garbage collection disabled, expanded heap instead");
217 }
218 return success;
219 }
220
221 bool PSOldGen::expand_by(size_t bytes) {
222 assert_lock_strong(PSOldGenExpand_lock);
223 assert_locked_or_safepoint(Heap_lock);
224 assert(bytes > 0, "precondition");
225 bool result = virtual_space()->expand_by(bytes);
226 if (result) {
227 if (ZapUnusedHeapArea) {
228 // We need to mangle the newly expanded area. The memregion spans
229 // end -> new_end, we assume that top -> end is already mangled.
230 // Do the mangling before post_resize() is called because
231 // the space is available for allocation after post_resize();
232 HeapWord* const virtual_space_high = (HeapWord*) virtual_space()->high();
233 assert(object_space()->end() < virtual_space_high,
234 "Should be true before post_resize()");
235 MemRegion mangle_region(object_space()->end(), virtual_space_high);
236 // Note that the object space has not yet been updated to
237 // coincide with the new underlying virtual space.
238 SpaceMangler::mangle_region(mangle_region);
239 }
240 post_resize();
241 if (UsePerfData) {
242 _space_counters->update_capacity();
243 _gen_counters->update_all();
244 }
245 }
246
247 if (result) {
248 size_t new_mem_size = virtual_space()->committed_size();
249 size_t old_mem_size = new_mem_size - bytes;
250 log_debug(gc)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
251 name(), old_mem_size/K, bytes/K, new_mem_size/K);
252 }
253
254 return result;
255 }
256
257 bool PSOldGen::expand_to_reserved() {
258 assert_lock_strong(PSOldGenExpand_lock);
259 assert_locked_or_safepoint(Heap_lock);
260
261 bool result = false;
262 const size_t remaining_bytes = virtual_space()->uncommitted_size();
263 if (remaining_bytes > 0) {
264 result = expand_by(remaining_bytes);
265 DEBUG_ONLY(if (!result) log_warning(gc)("grow to reserve failed"));
266 }
267 return result;
268 }
269
270 void PSOldGen::shrink(size_t bytes) {
271 assert_lock_strong(PSOldGenExpand_lock);
272 assert_locked_or_safepoint(Heap_lock);
273
274 size_t size = align_down(bytes, virtual_space()->alignment());
275 if (size > 0) {
276 virtual_space()->shrink_by(bytes);
277 post_resize();
278
279 size_t new_mem_size = virtual_space()->committed_size();
280 size_t old_mem_size = new_mem_size + bytes;
281 log_debug(gc)("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
282 name(), old_mem_size/K, bytes/K, new_mem_size/K);
283 }
284 }
285
286 void PSOldGen::complete_loaded_archive_space(MemRegion archive_space) {
287 HeapWord* cur = archive_space.start();
288 while (cur < archive_space.end()) {
289 _start_array.allocate_block(cur);
290 size_t word_size = cast_to_oop(cur)->size();
291 cur += word_size;
292 }
293 }
294
295 void PSOldGen::resize(size_t desired_free_space) {
296 const size_t alignment = virtual_space()->alignment();
297 const size_t size_before = virtual_space()->committed_size();
298 size_t new_size = used_in_bytes() + desired_free_space;
299 if (new_size < used_in_bytes()) {
300 // Overflowed the addition.
301 new_size = max_gen_size();
302 }
303 // Adjust according to our min and max
304 new_size = clamp(new_size, min_gen_size(), max_gen_size());
305
306 new_size = align_up(new_size, alignment);
307
308 const size_t current_size = capacity_in_bytes();
309
310 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: "
311 "desired free: " SIZE_FORMAT " used: " SIZE_FORMAT
312 " new size: " SIZE_FORMAT " current size " SIZE_FORMAT
313 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
314 desired_free_space, used_in_bytes(), new_size, current_size,
315 max_gen_size(), min_gen_size());
316
317 if (new_size == current_size) {
318 // No change requested
319 return;
320 }
321 if (new_size > current_size) {
322 size_t change_bytes = new_size - current_size;
323 MutexLocker x(PSOldGenExpand_lock);
324 expand(change_bytes);
325 } else {
326 size_t change_bytes = current_size - new_size;
327 MutexLocker x(PSOldGenExpand_lock);
328 shrink(change_bytes);
329 }
330
331 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: collection: %d (" SIZE_FORMAT ") -> (" SIZE_FORMAT ") ",
332 ParallelScavengeHeap::heap()->total_collections(),
333 size_before,
334 virtual_space()->committed_size());
335 }
336
337 // NOTE! We need to be careful about resizing. During a GC, multiple
338 // allocators may be active during heap expansion. If we allow the
339 // heap resizing to become visible before we have correctly resized
340 // all heap related data structures, we may cause program failures.
341 void PSOldGen::post_resize() {
342 // First construct a memregion representing the new size
343 MemRegion new_memregion((HeapWord*)virtual_space()->low(),
344 (HeapWord*)virtual_space()->high());
345 size_t new_word_size = new_memregion.word_size();
346
347 start_array()->set_covered_region(new_memregion);
348 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(new_memregion);
349
350 WorkerThreads* workers = Thread::current()->is_VM_thread() ?
351 &ParallelScavengeHeap::heap()->workers() : nullptr;
352
353 // The update of the space's end is done by this call. As that
354 // makes the new space available for concurrent allocation, this
355 // must be the last step when expanding.
356 object_space()->initialize(new_memregion,
357 SpaceDecorator::DontClear,
358 SpaceDecorator::DontMangle,
359 MutableSpace::SetupPages,
360 workers);
361
362 assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()),
363 "Sanity");
364 }
365
366 void PSOldGen::print() const { print_on(tty);}
367 void PSOldGen::print_on(outputStream* st) const {
368 st->print(" %-15s", name());
369 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
370 capacity_in_bytes()/K, used_in_bytes()/K);
371 st->print_cr(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
372 p2i(virtual_space()->low_boundary()),
373 p2i(virtual_space()->high()),
374 p2i(virtual_space()->high_boundary()));
375
376 st->print(" object"); object_space()->print_on(st);
377 }
378
379 void PSOldGen::update_counters() {
380 if (UsePerfData) {
381 _space_counters->update_all();
382 _gen_counters->update_all();
383 }
384 }
385
386 void PSOldGen::verify() {
387 object_space()->verify();
388 }
389
390 class VerifyObjectStartArrayClosure : public ObjectClosure {
391 ObjectStartArray* _start_array;
392
393 public:
394 VerifyObjectStartArrayClosure(ObjectStartArray* start_array) :
395 _start_array(start_array) { }
396
397 virtual void do_object(oop obj) {
398 HeapWord* test_addr = cast_from_oop<HeapWord*>(obj) + 1;
399 guarantee(_start_array->object_start(test_addr) == cast_from_oop<HeapWord*>(obj), "ObjectStartArray cannot find start of object");
400 guarantee(_start_array->is_block_allocated(cast_from_oop<HeapWord*>(obj)), "ObjectStartArray missing block allocation");
401 }
402 };
403
404 void PSOldGen::verify_object_start_array() {
405 VerifyObjectStartArrayClosure check(&_start_array);
406 object_iterate(&check);
407 }
408
409 #ifndef PRODUCT
410 void PSOldGen::record_spaces_top() {
411 assert(ZapUnusedHeapArea, "Not mangling unused space");
412 object_space()->set_top_for_allocations();
413 }
414 #endif