1 /*
2 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "gc/epsilon/epsilonHeap.hpp"
26 #include "gc/epsilon/epsilonMemoryPool.hpp"
27 #include "gc/epsilon/epsilonThreadLocalData.hpp"
28 #include "gc/shared/gcArguments.hpp"
29 #include "gc/shared/locationPrinter.inline.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "memory/universe.hpp"
34 #include "runtime/globals.hpp"
35
36 jint EpsilonHeap::initialize() {
37 size_t align = HeapAlignment;
38 size_t init_byte_size = align_up(InitialHeapSize, align);
39 size_t max_byte_size = align_up(MaxHeapSize, align);
40
41 // Initialize backing storage
42 ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, align);
43 _virtual_space.initialize(heap_rs, init_byte_size);
44
45 MemRegion committed_region((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
46 MemRegion reserved_region((HeapWord*)_virtual_space.low_boundary(), (HeapWord*)_virtual_space.high_boundary());
47
48 initialize_reserved_region(heap_rs);
49
50 _space = new ContiguousSpace();
51 _space->initialize(committed_region, /* clear_space = */ true, /* mangle_space = */ true);
52
53 // Precompute hot fields
54 _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), align_object_size(EpsilonMaxTLABSize / HeapWordSize));
55 _step_counter_update = MIN2<size_t>(max_byte_size / 16, EpsilonUpdateCountersStep);
56 _step_heap_print = (EpsilonPrintHeapSteps == 0) ? SIZE_MAX : (max_byte_size / EpsilonPrintHeapSteps);
57 _decay_time_ns = (int64_t) EpsilonTLABDecayTime * NANOSECS_PER_MILLISEC;
58
59 // Enable monitoring
60 _monitoring_support = new EpsilonMonitoringSupport(this);
61 _last_counter_update = 0;
62 _last_heap_print = 0;
63
64 // Install barrier set
65 BarrierSet::set_barrier_set(new EpsilonBarrierSet());
66
67 // All done, print out the configuration
68 if (init_byte_size != max_byte_size) {
69 log_info(gc)("Resizeable heap; starting at " SIZE_FORMAT "M, max: " SIZE_FORMAT "M, step: " SIZE_FORMAT "M",
70 init_byte_size / M, max_byte_size / M, EpsilonMinHeapExpand / M);
71 } else {
72 log_info(gc)("Non-resizeable heap; start/max: " SIZE_FORMAT "M", init_byte_size / M);
73 }
74
75 if (UseTLAB) {
76 log_info(gc)("Using TLAB allocation; max: " SIZE_FORMAT "K", _max_tlab_size * HeapWordSize / K);
77 if (EpsilonElasticTLAB) {
78 log_info(gc)("Elastic TLABs enabled; elasticity: %.2fx", EpsilonTLABElasticity);
79 }
80 if (EpsilonElasticTLABDecay) {
81 log_info(gc)("Elastic TLABs decay enabled; decay time: " SIZE_FORMAT "ms", EpsilonTLABDecayTime);
82 }
83 } else {
84 log_info(gc)("Not using TLAB allocation");
85 }
86
87 return JNI_OK;
88 }
89
90 void EpsilonHeap::post_initialize() {
91 CollectedHeap::post_initialize();
92 }
93
94 void EpsilonHeap::initialize_serviceability() {
95 _pool = new EpsilonMemoryPool(this);
96 _memory_manager.add_pool(_pool);
97 }
98
99 GrowableArray<GCMemoryManager*> EpsilonHeap::memory_managers() {
100 GrowableArray<GCMemoryManager*> memory_managers(1);
101 memory_managers.append(&_memory_manager);
102 return memory_managers;
103 }
104
105 GrowableArray<MemoryPool*> EpsilonHeap::memory_pools() {
106 GrowableArray<MemoryPool*> memory_pools(1);
107 memory_pools.append(_pool);
108 return memory_pools;
109 }
110
111 size_t EpsilonHeap::unsafe_max_tlab_alloc(Thread* thr) const {
112 // Return max allocatable TLAB size, and let allocation path figure out
113 // the actual allocation size. Note: result should be in bytes.
114 return _max_tlab_size * HeapWordSize;
115 }
116
117 EpsilonHeap* EpsilonHeap::heap() {
118 CollectedHeap* heap = Universe::heap();
119 assert(heap != NULL, "Uninitialized access to EpsilonHeap::heap()");
120 assert(heap->kind() == CollectedHeap::Epsilon, "Not an Epsilon heap");
121 return (EpsilonHeap*)heap;
122 }
123
124 HeapWord* EpsilonHeap::allocate_work(size_t size) {
125 assert(is_object_aligned(size), "Allocation size should be aligned: " SIZE_FORMAT, size);
126
127 HeapWord* res = _space->par_allocate(size);
128
129 while (res == NULL) {
130 // Allocation failed, attempt expansion, and retry:
131 MutexLocker ml(Heap_lock);
132
133 size_t space_left = max_capacity() - capacity();
134 size_t want_space = MAX2(size, EpsilonMinHeapExpand);
135
136 if (want_space < space_left) {
137 // Enough space to expand in bulk:
138 bool expand = _virtual_space.expand_by(want_space);
139 assert(expand, "Should be able to expand");
140 } else if (size < space_left) {
141 // No space to expand in bulk, and this allocation is still possible,
142 // take all the remaining space:
143 bool expand = _virtual_space.expand_by(space_left);
144 assert(expand, "Should be able to expand");
145 } else {
146 // No space left:
147 return NULL;
148 }
149
150 _space->set_end((HeapWord *) _virtual_space.high());
151 res = _space->par_allocate(size);
152 }
153
154 size_t used = _space->used();
155
156 // Allocation successful, update counters
157 {
158 size_t last = _last_counter_update;
159 if ((used - last >= _step_counter_update) && Atomic::cmpxchg(used, &_last_counter_update, last) == last) {
160 _monitoring_support->update_counters();
161 }
162 }
163
164 // ...and print the occupancy line, if needed
165 {
166 size_t last = _last_heap_print;
167 if ((used - last >= _step_heap_print) && Atomic::cmpxchg(used, &_last_heap_print, last) == last) {
168 print_heap_info(used);
169 print_metaspace_info();
170 }
171 }
172
173 assert(is_object_aligned(res), "Object should be aligned: " PTR_FORMAT, p2i(res));
174 return res;
175 }
176
177 HeapWord* EpsilonHeap::allocate_new_tlab(size_t min_size,
178 size_t requested_size,
179 size_t* actual_size) {
180 Thread* thread = Thread::current();
181
182 // Defaults in case elastic paths are not taken
183 bool fits = true;
184 size_t size = requested_size;
185 size_t ergo_tlab = requested_size;
186 int64_t time = 0;
187
188 if (EpsilonElasticTLAB) {
189 ergo_tlab = EpsilonThreadLocalData::ergo_tlab_size(thread);
190
191 if (EpsilonElasticTLABDecay) {
192 int64_t last_time = EpsilonThreadLocalData::last_tlab_time(thread);
193 time = (int64_t) os::javaTimeNanos();
194
195 assert(last_time <= time, "time should be monotonic");
196
197 // If the thread had not allocated recently, retract the ergonomic size.
198 // This conserves memory when the thread had initial burst of allocations,
199 // and then started allocating only sporadically.
200 if (last_time != 0 && (time - last_time > _decay_time_ns)) {
201 ergo_tlab = 0;
202 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
203 }
204 }
205
206 // If we can fit the allocation under current TLAB size, do so.
207 // Otherwise, we want to elastically increase the TLAB size.
208 fits = (requested_size <= ergo_tlab);
209 if (!fits) {
210 size = (size_t) (ergo_tlab * EpsilonTLABElasticity);
211 }
212 }
213
214 // Always honor boundaries
215 size = MAX2(min_size, MIN2(_max_tlab_size, size));
216
217 // Always honor alignment
218 size = align_up(size, MinObjAlignment);
219
220 // Check that adjustments did not break local and global invariants
221 assert(is_object_aligned(size),
222 "Size honors object alignment: " SIZE_FORMAT, size);
223 assert(min_size <= size,
224 "Size honors min size: " SIZE_FORMAT " <= " SIZE_FORMAT, min_size, size);
225 assert(size <= _max_tlab_size,
226 "Size honors max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, _max_tlab_size);
227 assert(size <= CollectedHeap::max_tlab_size(),
228 "Size honors global max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, CollectedHeap::max_tlab_size());
229
230 if (log_is_enabled(Trace, gc)) {
231 ResourceMark rm;
232 log_trace(gc)("TLAB size for \"%s\" (Requested: " SIZE_FORMAT "K, Min: " SIZE_FORMAT
233 "K, Max: " SIZE_FORMAT "K, Ergo: " SIZE_FORMAT "K) -> " SIZE_FORMAT "K",
234 thread->name(),
235 requested_size * HeapWordSize / K,
236 min_size * HeapWordSize / K,
237 _max_tlab_size * HeapWordSize / K,
238 ergo_tlab * HeapWordSize / K,
239 size * HeapWordSize / K);
240 }
241
242 // All prepared, let's do it!
243 HeapWord* res = allocate_work(size);
244
245 if (res != NULL) {
246 // Allocation successful
247 *actual_size = size;
248 if (EpsilonElasticTLABDecay) {
249 EpsilonThreadLocalData::set_last_tlab_time(thread, time);
250 }
251 if (EpsilonElasticTLAB && !fits) {
252 // If we requested expansion, this is our new ergonomic TLAB size
253 EpsilonThreadLocalData::set_ergo_tlab_size(thread, size);
254 }
255 } else {
256 // Allocation failed, reset ergonomics to try and fit smaller TLABs
257 if (EpsilonElasticTLAB) {
258 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
259 }
260 }
261
262 return res;
263 }
264
265 HeapWord* EpsilonHeap::mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded) {
266 *gc_overhead_limit_was_exceeded = false;
267 return allocate_work(size);
268 }
269
270 void EpsilonHeap::collect(GCCause::Cause cause) {
271 switch (cause) {
272 case GCCause::_metadata_GC_threshold:
273 case GCCause::_metadata_GC_clear_soft_refs:
274 // Receiving these causes means the VM itself entered the safepoint for metadata collection.
275 // While Epsilon does not do GC, it has to perform sizing adjustments, otherwise we would
276 // re-enter the safepoint again very soon.
277
278 assert(SafepointSynchronize::is_at_safepoint(), "Expected at safepoint");
279 log_info(gc)("GC request for \"%s\" is handled", GCCause::to_string(cause));
280 MetaspaceGC::compute_new_size();
281 print_metaspace_info();
282 break;
283 default:
284 log_info(gc)("GC request for \"%s\" is ignored", GCCause::to_string(cause));
285 }
286 _monitoring_support->update_counters();
287 }
288
289 void EpsilonHeap::do_full_collection(bool clear_all_soft_refs) {
290 collect(gc_cause());
291 }
292
293 void EpsilonHeap::safe_object_iterate(ObjectClosure *cl) {
294 _space->safe_object_iterate(cl);
295 }
296
297 void EpsilonHeap::print_on(outputStream *st) const {
298 st->print_cr("Epsilon Heap");
299
300 // Cast away constness:
301 ((VirtualSpace)_virtual_space).print_on(st);
302
303 st->print_cr("Allocation space:");
304 _space->print_on(st);
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 size_t reserved = MetaspaceUtils::reserved_bytes();
337 size_t committed = MetaspaceUtils::committed_bytes();
338 size_t used = MetaspaceUtils::used_bytes();
339
340 if (reserved != 0) {
341 log_info(gc, metaspace)("Metaspace: " SIZE_FORMAT "%s reserved, " SIZE_FORMAT "%s (%.2f%%) committed, "
342 SIZE_FORMAT "%s (%.2f%%) used",
343 byte_size_in_proper_unit(reserved), proper_unit_for_byte_size(reserved),
344 byte_size_in_proper_unit(committed), proper_unit_for_byte_size(committed),
345 committed * 100.0 / reserved,
346 byte_size_in_proper_unit(used), proper_unit_for_byte_size(used),
347 used * 100.0 / reserved);
348 } else {
349 log_info(gc, metaspace)("Metaspace: no reliable data");
350 }
351 }