1 /*
2 * Copyright (c) 2014, 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_implementation/g1/g1CollectedHeap.inline.hpp"
27 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
28 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "oops/oop.pcgc.inline.hpp"
31 #include "runtime/prefetch.inline.hpp"
32
33 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
34 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
35 #endif // _MSC_VER
36
37 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
38 : _g1h(g1h),
39 _refs(g1h->task_queue(queue_num)),
40 _dcq(&g1h->dirty_card_queue_set()),
41 _ct_bs(g1h->g1_barrier_set()),
42 _g1_rem(g1h->g1_rem_set()),
43 _hash_seed(17), _queue_num(queue_num),
44 _term_attempts(0),
45 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
46 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
47 _age_table(false), _scanner(g1h, this, rp),
48 _strong_roots_time(0), _term_time(0),
49 _alloc_buffer_waste(0), _undo_waste(0) {
50 // we allocate G1YoungSurvRateNumRegions plus one entries, since
51 // we "sacrifice" entry 0 to keep track of surviving bytes for
52 // non-young regions (where the age is -1)
53 // We also add a few elements at the beginning and at the end in
54 // an attempt to eliminate cache contention
55 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
56 uint array_length = PADDING_ELEM_NUM +
57 real_length +
58 PADDING_ELEM_NUM;
59 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
60 if (_surviving_young_words_base == NULL)
61 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
62 "Not enough space for young surv histo.");
63 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
64 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
65
66 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
67 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
68
69 _start = os::elapsedTime();
70 }
71
72 void
73 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
74 {
75 st->print_raw_cr("GC Termination Stats");
76 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
77 " ------waste (KiB)------");
78 st->print_raw_cr("thr ms ms % ms % attempts"
79 " total alloc undo");
80 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
81 " ------- ------- -------");
82 }
83
84 void
85 G1ParScanThreadState::print_termination_stats(int i,
86 outputStream* const st) const
87 {
88 const double elapsed_ms = elapsed_time() * 1000.0;
89 const double s_roots_ms = strong_roots_time() * 1000.0;
90 const double term_ms = term_time() * 1000.0;
91 st->print_cr("%3d %9.2f %9.2f %6.2f "
92 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
93 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
94 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
95 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
96 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
97 alloc_buffer_waste() * HeapWordSize / K,
98 undo_waste() * HeapWordSize / K);
99 }
100
101 #ifdef ASSERT
102 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
103 assert(ref != NULL, "invariant");
104 assert(UseCompressedOops, "sanity");
105 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, p2i(ref)));
106 oop p = oopDesc::load_decode_heap_oop(ref);
107 assert(_g1h->is_in_g1_reserved(p),
108 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
109 return true;
110 }
111
112 bool G1ParScanThreadState::verify_ref(oop* ref) const {
113 assert(ref != NULL, "invariant");
114 if (has_partial_array_mask(ref)) {
115 // Must be in the collection set--it's already been copied.
116 oop p = clear_partial_array_mask(ref);
117 assert(_g1h->obj_in_cs(p),
118 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
119 } else {
120 oop p = oopDesc::load_decode_heap_oop(ref);
121 assert(_g1h->is_in_g1_reserved(p),
122 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
123 }
124 return true;
125 }
126
127 bool G1ParScanThreadState::verify_task(StarTask ref) const {
128 if (ref.is_narrow()) {
129 return verify_ref((narrowOop*) ref);
130 } else {
131 return verify_ref((oop*) ref);
132 }
133 }
134 #endif // ASSERT
135
136 void G1ParScanThreadState::trim_queue() {
137 assert(_evac_failure_cl != NULL, "not set");
138
139 StarTask ref;
140 do {
141 // Drain the overflow stack first, so other threads can steal.
142 while (refs()->pop_overflow(ref)) {
143 deal_with_reference(ref);
144 }
145
146 while (refs()->pop_local(ref)) {
147 deal_with_reference(ref);
148 }
149 } while (!refs()->is_empty());
150 }
151
152 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
153 size_t word_sz = old->size();
154 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
155 // +1 to make the -1 indexes valid...
156 int young_index = from_region->young_index_in_cset()+1;
157 assert( (from_region->is_young() && young_index > 0) ||
158 (!from_region->is_young() && young_index == 0), "invariant" );
159 G1CollectorPolicy* g1p = _g1h->g1_policy();
160 markOop m = old->mark();
161 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
162 : m->age();
163 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
164 word_sz);
165 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
166 #ifndef PRODUCT
167 // Should this evacuation fail?
168 if (_g1h->evacuation_should_fail()) {
169 if (obj_ptr != NULL) {
170 undo_allocation(alloc_purpose, obj_ptr, word_sz);
171 obj_ptr = NULL;
172 }
173 }
174 #endif // !PRODUCT
175
176 if (obj_ptr == NULL) {
177 // This will either forward-to-self, or detect that someone else has
178 // installed a forwarding pointer.
179 return _g1h->handle_evacuation_failure_par(this, old);
180 }
181
182 oop obj = oop(obj_ptr);
183
184 // We're going to allocate linearly, so might as well prefetch ahead.
185 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
186
187 oop forward_ptr = old->forward_to_atomic(obj);
188 if (forward_ptr == NULL) {
189 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
190
191 // alloc_purpose is just a hint to allocate() above, recheck the type of region
192 // we actually allocated from and update alloc_purpose accordingly
193 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
194 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
195
196 if (g1p->track_object_age(alloc_purpose)) {
197 // We could simply do obj->incr_age(). However, this causes a
198 // performance issue. obj->incr_age() will first check whether
199 // the object has a displaced mark by checking its mark word;
200 // getting the mark word from the new location of the object
201 // stalls. So, given that we already have the mark word and we
202 // are about to install it anyway, it's better to increase the
203 // age on the mark word, when the object does not have a
204 // displaced mark word. We're not expecting many objects to have
205 // a displaced marked word, so that case is not optimized
206 // further (it could be...) and we simply call obj->incr_age().
207
208 if (m->has_displaced_mark_helper()) {
209 // in this case, we have to install the mark word first,
210 // otherwise obj looks to be forwarded (the old mark word,
211 // which contains the forward pointer, was copied)
212 obj->set_mark(m);
213 obj->incr_age();
214 } else {
215 m = m->incr_age();
216 obj->set_mark(m);
217 }
218 age_table()->add(obj, word_sz);
219 } else {
220 obj->set_mark(m);
221 }
222
223 if (G1StringDedup::is_enabled()) {
224 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
225 to_region->is_young(),
226 queue_num(),
227 obj);
228 }
229
230 size_t* surv_young_words = surviving_young_words();
231 surv_young_words[young_index] += word_sz;
232
233 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
234 // We keep track of the next start index in the length field of
235 // the to-space object. The actual length can be found in the
236 // length field of the from-space object.
237 arrayOop(obj)->set_length(0);
238 oop* old_p = set_partial_array_mask(old);
239 push_on_queue(old_p);
240 } else {
241 // No point in using the slower heap_region_containing() method,
242 // given that we know obj is in the heap.
243 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
244 obj->oop_iterate_backwards(&_scanner);
245 }
246 } else {
247 undo_allocation(alloc_purpose, obj_ptr, word_sz);
248 obj = forward_ptr;
249 }
250 return obj;
251 }