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 "memory/allocation.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31
32 jint EpsilonHeap::initialize() {
33 size_t align = _policy->heap_alignment();
34 size_t init_byte_size = align_up(_policy->initial_heap_byte_size(), align);
35 size_t max_byte_size = align_up(_policy->max_heap_byte_size(), align);
36
37 // Initialize backing storage
38 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, align);
39 _virtual_space.initialize(heap_rs, init_byte_size);
40
41 MemRegion committed_region((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
42 MemRegion reserved_region((HeapWord*)_virtual_space.low_boundary(), (HeapWord*)_virtual_space.high_boundary());
43
44 initialize_reserved_region(reserved_region.start(), reserved_region.end());
45
46 _space = new ContiguousSpace();
47 _space->initialize(committed_region, /* clear_space = */ true, /* mangle_space = */ true);
48
49 // Precompute hot fields
50 _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), align_object_size(EpsilonMaxTLABSize / HeapWordSize));
51 _step_counter_update = MIN2<size_t>(max_byte_size / 16, EpsilonUpdateCountersStep);
52 _step_heap_print = (EpsilonPrintHeapSteps == 0) ? SIZE_MAX : (max_byte_size / EpsilonPrintHeapSteps);
53 _decay_time_ns = (int64_t) EpsilonTLABDecayTime * NANOSECS_PER_MILLISEC;
54
55 // Enable monitoring
56 _monitoring_support = new EpsilonMonitoringSupport(this);
57 _last_counter_update = 0;
58 _last_heap_print = 0;
59
60 // Install barrier set
61 BarrierSet::set_barrier_set(new EpsilonBarrierSet());
62
63 // All done, print out the configuration
64 if (init_byte_size != max_byte_size) {
65 log_info(gc)("Resizeable heap; starting at " SIZE_FORMAT "M, max: " SIZE_FORMAT "M, step: " SIZE_FORMAT "M",
66 init_byte_size / M, max_byte_size / M, EpsilonMinHeapExpand / M);
67 } else {
68 log_info(gc)("Non-resizeable heap; start/max: " SIZE_FORMAT "M", init_byte_size / M);
69 }
70
71 if (UseTLAB) {
72 log_info(gc)("Using TLAB allocation; max: " SIZE_FORMAT "K", _max_tlab_size * HeapWordSize / K);
73 if (EpsilonElasticTLAB) {
74 log_info(gc)("Elastic TLABs enabled; elasticity: %.2fx", EpsilonTLABElasticity);
75 }
76 if (EpsilonElasticTLABDecay) {
77 log_info(gc)("Elastic TLABs decay enabled; decay time: " SIZE_FORMAT "ms", EpsilonTLABDecayTime);
78 }
79 } else {
80 log_info(gc)("Not using TLAB allocation");
81 }
82
83 return JNI_OK;
84 }
85
86 void EpsilonHeap::post_initialize() {
87 CollectedHeap::post_initialize();
88 }
89
90 void EpsilonHeap::initialize_serviceability() {
91 _pool = new EpsilonMemoryPool(this);
92 _memory_manager.add_pool(_pool);
93 }
94
95 GrowableArray<GCMemoryManager*> EpsilonHeap::memory_managers() {
96 GrowableArray<GCMemoryManager*> memory_managers(1);
97 memory_managers.append(&_memory_manager);
98 return memory_managers;
99 }
100
101 GrowableArray<MemoryPool*> EpsilonHeap::memory_pools() {
102 GrowableArray<MemoryPool*> memory_pools(1);
103 memory_pools.append(_pool);
104 return memory_pools;
105 }
106
107 size_t EpsilonHeap::unsafe_max_tlab_alloc(Thread* thr) const {
108 // Return max allocatable TLAB size, and let allocation path figure out
109 // the actual TLAB allocation size.
110 return _max_tlab_size;
111 }
112
113 EpsilonHeap* EpsilonHeap::heap() {
114 CollectedHeap* heap = Universe::heap();
115 assert(heap != NULL, "Uninitialized access to EpsilonHeap::heap()");
116 assert(heap->kind() == CollectedHeap::Epsilon, "Not an Epsilon heap");
117 return (EpsilonHeap*)heap;
118 }
119
120 HeapWord* EpsilonHeap::allocate_work(size_t size) {
121 assert(is_object_aligned(size), "Allocation size should be aligned: " SIZE_FORMAT, size);
122
123 HeapWord* res = _space->par_allocate(size);
124
125 while (res == NULL) {
126 // Allocation failed, attempt expansion, and retry:
127 MutexLockerEx ml(Heap_lock);
128
129 size_t space_left = max_capacity() - capacity();
130 size_t want_space = MAX2(size, EpsilonMinHeapExpand);
131
132 if (want_space < space_left) {
133 // Enough space to expand in bulk:
134 bool expand = _virtual_space.expand_by(want_space);
135 assert(expand, "Should be able to expand");
136 } else if (size < space_left) {
137 // No space to expand in bulk, and this allocation is still possible,
138 // take all the remaining space:
139 bool expand = _virtual_space.expand_by(space_left);
140 assert(expand, "Should be able to expand");
141 } else {
142 // No space left:
143 return NULL;
144 }
145
146 _space->set_end((HeapWord *) _virtual_space.high());
147 res = _space->par_allocate(size);
148 }
149
150 size_t used = _space->used();
151
152 // Allocation successful, update counters
153 {
154 size_t last = _last_counter_update;
155 if ((used - last >= _step_counter_update) && Atomic::cmpxchg(used, &_last_counter_update, last) == last) {
156 _monitoring_support->update_counters();
157 }
158 }
159
160 // ...and print the occupancy line, if needed
161 {
162 size_t last = _last_heap_print;
163 if ((used - last >= _step_heap_print) && Atomic::cmpxchg(used, &_last_heap_print, last) == last) {
164 print_heap_info(used);
165 print_metaspace_info();
166 }
167 }
168
169 assert(is_object_aligned(res), "Object should be aligned: " PTR_FORMAT, p2i(res));
170 return res;
171 }
172
173 HeapWord* EpsilonHeap::allocate_new_tlab(size_t min_size,
174 size_t requested_size,
175 size_t* actual_size) {
176 Thread* thread = Thread::current();
177
178 // Defaults in case elastic paths are not taken
179 bool fits = true;
180 size_t size = requested_size;
181 size_t ergo_tlab = requested_size;
182 int64_t time = 0;
183
184 if (EpsilonElasticTLAB) {
185 ergo_tlab = EpsilonThreadLocalData::ergo_tlab_size(thread);
186
187 if (EpsilonElasticTLABDecay) {
188 int64_t last_time = EpsilonThreadLocalData::last_tlab_time(thread);
189 time = (int64_t) os::javaTimeNanos();
190
191 assert(last_time <= time, "time should be monotonic");
192
193 // If the thread had not allocated recently, retract the ergonomic size.
194 // This conserves memory when the thread had initial burst of allocations,
195 // and then started allocating only sporadically.
196 if (last_time != 0 && (time - last_time > _decay_time_ns)) {
197 ergo_tlab = 0;
198 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
199 }
200 }
201
202 // If we can fit the allocation under current TLAB size, do so.
203 // Otherwise, we want to elastically increase the TLAB size.
204 fits = (requested_size <= ergo_tlab);
205 if (!fits) {
206 size = (size_t) (ergo_tlab * EpsilonTLABElasticity);
207 }
208 }
209
210 // Always honor boundaries
211 size = MAX2(min_size, MIN2(_max_tlab_size, size));
212
213 // Always honor alignment
214 size = align_up(size, MinObjAlignment);
215
216 // Check that adjustments did not break local and global invariants
217 assert(is_object_aligned(size),
218 "Size honors object alignment: " SIZE_FORMAT, size);
219 assert(min_size <= size,
220 "Size honors min size: " SIZE_FORMAT " <= " SIZE_FORMAT, min_size, size);
221 assert(size <= _max_tlab_size,
222 "Size honors max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, _max_tlab_size);
223 assert(size <= CollectedHeap::max_tlab_size(),
224 "Size honors global max size: " SIZE_FORMAT " <= " SIZE_FORMAT, size, CollectedHeap::max_tlab_size());
225
226 if (log_is_enabled(Trace, gc)) {
227 ResourceMark rm;
228 log_trace(gc)("TLAB size for \"%s\" (Requested: " SIZE_FORMAT "K, Min: " SIZE_FORMAT
229 "K, Max: " SIZE_FORMAT "K, Ergo: " SIZE_FORMAT "K) -> " SIZE_FORMAT "K",
230 thread->name(),
231 requested_size * HeapWordSize / K,
232 min_size * HeapWordSize / K,
233 _max_tlab_size * HeapWordSize / K,
234 ergo_tlab * HeapWordSize / K,
235 size * HeapWordSize / K);
236 }
237
238 // All prepared, let's do it!
239 HeapWord* res = allocate_work(size);
240
241 if (res != NULL) {
242 // Allocation successful
243 *actual_size = size;
244 if (EpsilonElasticTLABDecay) {
245 EpsilonThreadLocalData::set_last_tlab_time(thread, time);
246 }
247 if (EpsilonElasticTLAB && !fits) {
248 // If we requested expansion, this is our new ergonomic TLAB size
249 EpsilonThreadLocalData::set_ergo_tlab_size(thread, size);
250 }
251 } else {
252 // Allocation failed, reset ergonomics to try and fit smaller TLABs
253 if (EpsilonElasticTLAB) {
254 EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);
255 }
256 }
257
258 return res;
259 }
260
261 HeapWord* EpsilonHeap::mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded) {
262 *gc_overhead_limit_was_exceeded = false;
263 return allocate_work(size);
264 }
265
266 void EpsilonHeap::collect(GCCause::Cause cause) {
267 switch (cause) {
268 case GCCause::_metadata_GC_threshold:
269 case GCCause::_metadata_GC_clear_soft_refs:
270 // Receiving these causes means the VM itself entered the safepoint for metadata collection.
271 // While Epsilon does not do GC, it has to perform sizing adjustments, otherwise we would
272 // re-enter the safepoint again very soon.
273
274 assert(SafepointSynchronize::is_at_safepoint(), "Expected at safepoint");
275 log_info(gc)("GC request for \"%s\" is handled", GCCause::to_string(cause));
276 MetaspaceGC::compute_new_size();
277 print_metaspace_info();
278 break;
279 default:
280 log_info(gc)("GC request for \"%s\" is ignored", GCCause::to_string(cause));
281 }
282 _monitoring_support->update_counters();
283 }
284
285 void EpsilonHeap::do_full_collection(bool clear_all_soft_refs) {
286 collect(gc_cause());
287 }
288
289 void EpsilonHeap::safe_object_iterate(ObjectClosure *cl) {
290 _space->safe_object_iterate(cl);
291 }
292
293 void EpsilonHeap::print_on(outputStream *st) const {
294 st->print_cr("Epsilon Heap");
295
296 // Cast away constness:
297 ((VirtualSpace)_virtual_space).print_on(st);
298
299 st->print_cr("Allocation space:");
300 _space->print_on(st);
301
302 MetaspaceUtils::print_on(st);
303 }
304
305 void EpsilonHeap::print_tracing_info() const {
306 print_heap_info(used());
307 print_metaspace_info();
308 }
309
310 void EpsilonHeap::print_heap_info(size_t used) const {
311 size_t reserved = max_capacity();
312 size_t committed = capacity();
313
314 log_info(gc)("Heap: " SIZE_FORMAT "M reserved, " SIZE_FORMAT "M (%.2f%%) committed, " SIZE_FORMAT "M (%.2f%%) used",
315 reserved / M,
316 committed / M,
317 committed * 100.0 / reserved,
318 used / M,
319 used * 100.0 / reserved);
320 }
321
322 void EpsilonHeap::print_metaspace_info() const {
323 size_t reserved = MetaspaceUtils::reserved_bytes();
324 size_t committed = MetaspaceUtils::committed_bytes();
325 size_t used = MetaspaceUtils::used_bytes();
326 log_info(gc,metaspace)("Metaspace: " SIZE_FORMAT "M reserved, " SIZE_FORMAT "M (%.2f%%) committed, " SIZE_FORMAT "M (%.2f%%) used",
327 reserved / M,
328 committed / M,
329 committed * 100.0 / reserved,
330 used / M,
331 used * 100.0 / reserved);
332 }