1 /*
2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2017, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
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24 */
25
26 #include "precompiled.hpp"
27 #include "gc/epsilon/epsilonHeap.hpp"
28 #include "gc/epsilon/epsilonInitLogger.hpp"
29 #include "gc/epsilon/epsilonMemoryPool.hpp"
30 #include "gc/epsilon/epsilonThreadLocalData.hpp"
31 #include "gc/shared/gcArguments.hpp"
32 #include "gc/shared/locationPrinter.inline.hpp"
33 #include "logging/log.hpp"
34 #include "memory/allocation.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/metaspaceUtils.hpp"
37 #include "memory/resourceArea.hpp"
38 #include "memory/universe.hpp"
39 #include "runtime/atomic.hpp"
40 #include "runtime/globals.hpp"
41
42 jint EpsilonHeap::initialize() {
43 size_t align = HeapAlignment;
44 size_t init_byte_size = align_up(InitialHeapSize, align);
45 size_t max_byte_size = align_up(MaxHeapSize, align);
46
47 // Initialize backing storage
48 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, align);
49 _virtual_space.initialize(heap_rs, init_byte_size);
50
51 MemRegion committed_region((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
52
53 initialize_reserved_region(heap_rs);
54
55 _space = new ContiguousSpace();
56 _space->initialize(committed_region, /* clear_space = */ true, /* mangle_space = */ true);
57
58 // Precompute hot fields
59 _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), align_object_size(EpsilonMaxTLABSize / HeapWordSize));
60 _step_counter_update = MIN2<size_t>(max_byte_size / 16, EpsilonUpdateCountersStep);
61 _step_heap_print = (EpsilonPrintHeapSteps == 0) ? SIZE_MAX : (max_byte_size / EpsilonPrintHeapSteps);
62 _decay_time_ns = (int64_t) EpsilonTLABDecayTime * NANOSECS_PER_MILLISEC;
63
64 // Enable monitoring
65 _monitoring_support = new EpsilonMonitoringSupport(this);
66 _last_counter_update = 0;
67 _last_heap_print = 0;
68
69 // Install barrier set
70 BarrierSet::set_barrier_set(new EpsilonBarrierSet());
71
72 // All done, print out the configuration
73 EpsilonInitLogger::print();
74
75 return JNI_OK;
76 }
77
78 void EpsilonHeap::initialize_serviceability() {
79 _pool = new EpsilonMemoryPool(this);
80 _memory_manager.add_pool(_pool);
81 }
82
83 GrowableArray<GCMemoryManager*> EpsilonHeap::memory_managers() {
84 GrowableArray<GCMemoryManager*> memory_managers(1);
85 memory_managers.append(&_memory_manager);
86 return memory_managers;
87 }
88
89 GrowableArray<MemoryPool*> EpsilonHeap::memory_pools() {
90 GrowableArray<MemoryPool*> memory_pools(1);
91 memory_pools.append(_pool);
92 return memory_pools;
93 }
94
95 size_t EpsilonHeap::unsafe_max_tlab_alloc(Thread* thr) const {
96 // Return max allocatable TLAB size, and let allocation path figure out
97 // the actual allocation size. Note: result should be in bytes.
98 return _max_tlab_size * HeapWordSize;
99 }
100
101 EpsilonHeap* EpsilonHeap::heap() {
102 return named_heap<EpsilonHeap>(CollectedHeap::Epsilon);
103 }
104
105 HeapWord* EpsilonHeap::allocate_work(size_t size, bool verbose) {
106 assert(is_object_aligned(size), "Allocation size should be aligned: " SIZE_FORMAT, size);
107
108 HeapWord* res = nullptr;
109 while (true) {
110 // Try to allocate, assume space is available
111 res = _space->par_allocate(size);
112 if (res != nullptr) {
113 break;
114 }
115
116 // Allocation failed, attempt expansion, and retry:
117 {
118 MutexLocker ml(Heap_lock);
119
120 // Try to allocate under the lock, assume another thread was able to expand
121 res = _space->par_allocate(size);
122 if (res != nullptr) {
123 break;
124 }
125
126 // Expand and loop back if space is available
127 size_t space_left = max_capacity() - capacity();
128 size_t want_space = MAX2(size, EpsilonMinHeapExpand);
129
130 if (want_space < space_left) {
131 // Enough space to expand in bulk:
132 bool expand = _virtual_space.expand_by(want_space);
133 assert(expand, "Should be able to expand");
134 } else if (size < space_left) {
135 // No space to expand in bulk, and this allocation is still possible,
136 // take all the remaining space:
137 bool expand = _virtual_space.expand_by(space_left);
138 assert(expand, "Should be able to expand");
139 } else {
140 // No space left:
141 return nullptr;
142 }
143
144 _space->set_end((HeapWord *) _virtual_space.high());
145 }
146 }
147
148 size_t used = _space->used();
149
150 // Allocation successful, update counters
151 if (verbose) {
152 size_t last = _last_counter_update;
153 if ((used - last >= _step_counter_update) && Atomic::cmpxchg(&_last_counter_update, last, used) == last) {
154 _monitoring_support->update_counters();
155 }
156 }
157
158 // ...and print the occupancy line, if needed
159 if (verbose) {
160 size_t last = _last_heap_print;
161 if ((used - last >= _step_heap_print) && Atomic::cmpxchg(&_last_heap_print, last, used) == last) {
162 print_heap_info(used);
163 print_metaspace_info();
164 }
165 }
166
167 assert(is_object_aligned(res), "Object should be aligned: " PTR_FORMAT, p2i(res));
168 return res;
169 }
170
171 HeapWord* EpsilonHeap::allocate_new_tlab(size_t min_size,
172 size_t requested_size,
173 size_t* actual_size) {
174 Thread* thread = Thread::current();
175
176 // Defaults in case elastic paths are not taken
177 bool fits = true;
178 size_t size = requested_size;
179 size_t ergo_tlab = requested_size;
180 int64_t time = 0;
181
182 if (EpsilonElasticTLAB) {
183 ergo_tlab = EpsilonThreadLocalData::ergo_tlab_size(thread);
184
185 if (EpsilonElasticTLABDecay) {
186 int64_t last_time = EpsilonThreadLocalData::last_tlab_time(thread);
187 time = (int64_t) os::javaTimeNanos();
188
189 assert(last_time <= time, "time should be monotonic");
190
191 // If the thread had not allocated recently, retract the ergonomic size.
192 // This conserves memory when the thread had initial burst of allocations,
193 // and then started allocating only sporadically.
194 if (last_time != 0 && (time - last_time > _decay_time_ns)) {
195 ergo_tlab = 0;
196 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
197 }
198 }
199
200 // If we can fit the allocation under current TLAB size, do so.
201 // Otherwise, we want to elastically increase the TLAB size.
202 fits = (requested_size <= ergo_tlab);
203 if (!fits) {
204 size = (size_t) (ergo_tlab * EpsilonTLABElasticity);
205 }
206 }
207
208 // Always honor boundaries
209 size = clamp(size, min_size, _max_tlab_size);
210
211 // Always honor alignment
212 size = align_up(size, MinObjAlignment);
213
214 // Check that adjustments did not break local and global invariants
215 assert(is_object_aligned(size),
216 "Size honors object alignment: " SIZE_FORMAT, size);
217 assert(min_size <= size,
218 "Size honors min size: " SIZE_FORMAT " <= " SIZE_FORMAT, min_size, size);
219 assert(size <= _max_tlab_size,
220 "Size honors max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, _max_tlab_size);
221 assert(size <= CollectedHeap::max_tlab_size(),
222 "Size honors global max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, CollectedHeap::max_tlab_size());
223
224 if (log_is_enabled(Trace, gc)) {
225 ResourceMark rm;
226 log_trace(gc)("TLAB size for \"%s\" (Requested: " SIZE_FORMAT "K, Min: " SIZE_FORMAT
227 "K, Max: " SIZE_FORMAT "K, Ergo: " SIZE_FORMAT "K) -> " SIZE_FORMAT "K",
228 thread->name(),
229 requested_size * HeapWordSize / K,
230 min_size * HeapWordSize / K,
231 _max_tlab_size * HeapWordSize / K,
232 ergo_tlab * HeapWordSize / K,
233 size * HeapWordSize / K);
234 }
235
236 // All prepared, let's do it!
237 HeapWord* res = allocate_work(size);
238
239 if (res != nullptr) {
240 // Allocation successful
241 *actual_size = size;
242 if (EpsilonElasticTLABDecay) {
243 EpsilonThreadLocalData::set_last_tlab_time(thread, time);
244 }
245 if (EpsilonElasticTLAB && !fits) {
246 // If we requested expansion, this is our new ergonomic TLAB size
247 EpsilonThreadLocalData::set_ergo_tlab_size(thread, size);
248 }
249 } else {
250 // Allocation failed, reset ergonomics to try and fit smaller TLABs
251 if (EpsilonElasticTLAB) {
252 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
253 }
254 }
255
256 return res;
257 }
258
259 HeapWord* EpsilonHeap::mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded) {
260 *gc_overhead_limit_was_exceeded = false;
261 return allocate_work(size);
262 }
263
264 HeapWord* EpsilonHeap::allocate_loaded_archive_space(size_t size) {
265 // Cannot use verbose=true because Metaspace is not initialized
266 return allocate_work(size, /* verbose = */false);
267 }
268
269 void EpsilonHeap::collect(GCCause::Cause cause) {
270 switch (cause) {
271 case GCCause::_metadata_GC_threshold:
272 case GCCause::_metadata_GC_clear_soft_refs:
273 // Receiving these causes means the VM itself entered the safepoint for metadata collection.
274 // While Epsilon does not do GC, it has to perform sizing adjustments, otherwise we would
275 // re-enter the safepoint again very soon.
276
277 assert(SafepointSynchronize::is_at_safepoint(), "Expected at safepoint");
278 log_info(gc)("GC request for \"%s\" is handled", GCCause::to_string(cause));
279 MetaspaceGC::compute_new_size();
280 print_metaspace_info();
281 break;
282 default:
283 log_info(gc)("GC request for \"%s\" is ignored", GCCause::to_string(cause));
284 }
285 _monitoring_support->update_counters();
286 }
287
288 void EpsilonHeap::do_full_collection(bool clear_all_soft_refs) {
289 collect(gc_cause());
290 }
291
292 void EpsilonHeap::object_iterate(ObjectClosure *cl) {
293 _space->object_iterate(cl);
294 }
295
296 void EpsilonHeap::print_on(outputStream *st) const {
297 st->print_cr("Epsilon Heap");
298
299 _virtual_space.print_on(st);
300
301 if (_space != nullptr) {
302 st->print_cr("Allocation space:");
303 _space->print_on(st);
304 }
305
306 MetaspaceUtils::print_on(st);
307 }
308
309 bool EpsilonHeap::print_location(outputStream* st, void* addr) const {
310 return BlockLocationPrinter<EpsilonHeap>::print_location(st, addr);
311 }
312
313 void EpsilonHeap::print_tracing_info() const {
314 print_heap_info(used());
315 print_metaspace_info();
316 }
317
318 void EpsilonHeap::print_heap_info(size_t used) const {
319 size_t reserved = max_capacity();
320 size_t committed = capacity();
321
322 if (reserved != 0) {
323 log_info(gc)("Heap: " SIZE_FORMAT "%s reserved, " SIZE_FORMAT "%s (%.2f%%) committed, "
324 SIZE_FORMAT "%s (%.2f%%) used",
325 byte_size_in_proper_unit(reserved), proper_unit_for_byte_size(reserved),
326 byte_size_in_proper_unit(committed), proper_unit_for_byte_size(committed),
327 committed * 100.0 / reserved,
328 byte_size_in_proper_unit(used), proper_unit_for_byte_size(used),
329 used * 100.0 / reserved);
330 } else {
331 log_info(gc)("Heap: no reliable data");
332 }
333 }
334
335 void EpsilonHeap::print_metaspace_info() const {
336 MetaspaceCombinedStats stats = MetaspaceUtils::get_combined_statistics();
337 size_t reserved = stats.reserved();
338 size_t committed = stats.committed();
339 size_t used = stats.used();
340
341 if (reserved != 0) {
342 log_info(gc, metaspace)("Metaspace: " SIZE_FORMAT "%s reserved, " SIZE_FORMAT "%s (%.2f%%) committed, "
343 SIZE_FORMAT "%s (%.2f%%) used",
344 byte_size_in_proper_unit(reserved), proper_unit_for_byte_size(reserved),
345 byte_size_in_proper_unit(committed), proper_unit_for_byte_size(committed),
346 committed * 100.0 / reserved,
347 byte_size_in_proper_unit(used), proper_unit_for_byte_size(used),
348 used * 100.0 / reserved);
349 } else {
350 log_info(gc, metaspace)("Metaspace: no reliable data");
351 }
352 }