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/mutableSpace.hpp"
27 #include "gc/shared/pretouchTask.hpp"
28 #include "gc/shared/spaceDecorator.inline.hpp"
29 #include "memory/iterator.inline.hpp"
30 #include "memory/universe.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/atomic.hpp"
33 #include "runtime/javaThread.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "utilities/align.hpp"
36 #include "utilities/macros.hpp"
37
38 MutableSpace::MutableSpace(size_t alignment) :
39 _mangler(nullptr),
40 _last_setup_region(),
41 _alignment(alignment),
42 _bottom(nullptr),
43 _top(nullptr),
44 _end(nullptr)
45 {
46 assert(MutableSpace::alignment() % os::vm_page_size() == 0,
47 "Space should be aligned");
48 _mangler = new MutableSpaceMangler(this);
49 }
50
51 MutableSpace::~MutableSpace() {
52 delete _mangler;
53 }
54
55 void MutableSpace::numa_setup_pages(MemRegion mr, size_t page_size, bool clear_space) {
56 if (!mr.is_empty()) {
57 HeapWord *start = align_up(mr.start(), page_size);
58 HeapWord *end = align_down(mr.end(), page_size);
59 if (end > start) {
60 size_t size = pointer_delta(end, start, sizeof(char));
61 if (clear_space) {
62 // Prefer page reallocation to migration.
63 os::free_memory((char*)start, size, page_size);
64 }
65 os::numa_make_global((char*)start, size);
66 }
67 }
68 }
69
70 void MutableSpace::initialize(MemRegion mr,
71 bool clear_space,
72 bool mangle_space,
73 bool setup_pages,
74 WorkerThreads* pretouch_workers) {
75
76 assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),
77 "invalid space boundaries");
78
79 if (setup_pages && (UseNUMA || AlwaysPreTouch)) {
80 // The space may move left and right or expand/shrink.
81 // We'd like to enforce the desired page placement.
82 MemRegion head, tail;
83 if (last_setup_region().is_empty()) {
84 // If it's the first initialization don't limit the amount of work.
85 head = mr;
86 tail = MemRegion(mr.end(), mr.end());
87 } else {
88 // Is there an intersection with the address space?
89 MemRegion intersection = last_setup_region().intersection(mr);
90 if (intersection.is_empty()) {
91 intersection = MemRegion(mr.end(), mr.end());
92 }
93 // All the sizes below are in words.
94 size_t head_size = 0, tail_size = 0;
95 if (mr.start() <= intersection.start()) {
96 head_size = pointer_delta(intersection.start(), mr.start());
97 }
98 if(intersection.end() <= mr.end()) {
99 tail_size = pointer_delta(mr.end(), intersection.end());
100 }
101 // Limit the amount of page manipulation if necessary.
102 if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {
103 const size_t change_size = head_size + tail_size;
104 const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;
105 head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),
106 head_size);
107 tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),
108 tail_size);
109 }
110 head = MemRegion(intersection.start() - head_size, intersection.start());
111 tail = MemRegion(intersection.end(), intersection.end() + tail_size);
112 }
113 assert(mr.contains(head) && mr.contains(tail), "Sanity");
114
115 size_t page_size = alignment();
116
117 if (UseNUMA) {
118 numa_setup_pages(head, page_size, clear_space);
119 numa_setup_pages(tail, page_size, clear_space);
120 }
121
122 if (AlwaysPreTouch) {
123 PretouchTask::pretouch("ParallelGC PreTouch head", (char*)head.start(), (char*)head.end(),
124 page_size, pretouch_workers);
125
126 PretouchTask::pretouch("ParallelGC PreTouch tail", (char*)tail.start(), (char*)tail.end(),
127 page_size, pretouch_workers);
128 }
129
130 // Remember where we stopped so that we can continue later.
131 set_last_setup_region(MemRegion(head.start(), tail.end()));
132 }
133
134 set_bottom(mr.start());
135 // When expanding concurrently with callers of cas_allocate, setting end
136 // makes the new space available for allocation by other threads. So this
137 // assignment must follow all other configuration and initialization that
138 // might be done for expansion.
139 Atomic::release_store(end_addr(), mr.end());
140
141 if (clear_space) {
142 clear(mangle_space);
143 }
144 }
145
146 void MutableSpace::clear(bool mangle_space) {
147 set_top(bottom());
148 if (ZapUnusedHeapArea && mangle_space) {
149 mangle_unused_area();
150 }
151 }
152
153 #ifndef PRODUCT
154 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
155 mangler()->check_mangled_unused_area(limit);
156 }
157
158 void MutableSpace::check_mangled_unused_area_complete() {
159 mangler()->check_mangled_unused_area_complete();
160 }
161
162 // Mangle only the unused space that has not previously
163 // been mangled and that has not been allocated since being
164 // mangled.
165 void MutableSpace::mangle_unused_area() {
166 mangler()->mangle_unused_area();
167 }
168
169 void MutableSpace::mangle_unused_area_complete() {
170 mangler()->mangle_unused_area_complete();
171 }
172
173 void MutableSpace::mangle_region(MemRegion mr) {
174 SpaceMangler::mangle_region(mr);
175 }
176
177 void MutableSpace::set_top_for_allocations(HeapWord* v) {
178 mangler()->set_top_for_allocations(v);
179 }
180
181 void MutableSpace::set_top_for_allocations() {
182 mangler()->set_top_for_allocations(top());
183 }
184 #endif
185
186 HeapWord* MutableSpace::cas_allocate(size_t size) {
187 do {
188 // Read top before end, else the range check may pass when it shouldn't.
189 // If end is read first, other threads may advance end and top such that
190 // current top > old end and current top + size > current end. Then
191 // pointer_delta underflows, allowing installation of top > current end.
192 HeapWord* obj = Atomic::load_acquire(top_addr());
193 if (pointer_delta(end(), obj) >= size) {
194 HeapWord* new_top = obj + size;
195 HeapWord* result = Atomic::cmpxchg(top_addr(), obj, new_top);
196 // result can be one of two:
197 // the old top value: the exchange succeeded
198 // otherwise: the new value of the top is returned.
199 if (result != obj) {
200 continue; // another thread beat us to the allocation, try again
201 }
202 assert(is_object_aligned(obj) && is_object_aligned(new_top),
203 "checking alignment");
204 return obj;
205 } else {
206 return nullptr;
207 }
208 } while (true);
209 }
210
211 // Try to deallocate previous allocation. Returns true upon success.
212 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
213 HeapWord* expected_top = obj + size;
214 return Atomic::cmpxchg(top_addr(), expected_top, obj) == expected_top;
215 }
216
217 // Only used by oldgen allocation.
218 bool MutableSpace::needs_expand(size_t word_size) const {
219 assert_lock_strong(PSOldGenExpand_lock);
220 // Holding the lock means end is stable. So while top may be advancing
221 // via concurrent allocations, there is no need to order the reads of top
222 // and end here, unlike in cas_allocate.
223 return pointer_delta(end(), top()) < word_size;
224 }
225
226 void MutableSpace::oop_iterate(OopIterateClosure* cl) {
227 HeapWord* obj_addr = bottom();
228 HeapWord* t = top();
229 // Could call objects iterate, but this is easier.
230 while (obj_addr < t) {
231 obj_addr += cast_to_oop(obj_addr)->oop_iterate_size(cl);
232 }
233 }
234
235 void MutableSpace::object_iterate(ObjectClosure* cl) {
236 HeapWord* p = bottom();
237 while (p < top()) {
238 oop obj = cast_to_oop(p);
239 // When promotion-failure occurs during Young GC, eden/from space is not cleared,
240 // so we can encounter objects with "forwarded" markword.
241 // They are essentially dead, so skipping them
242 if (!obj->is_forwarded()) {
243 cl->do_object(obj);
244 }
245 #ifdef ASSERT
246 else {
247 assert(obj->forwardee() != obj, "must not be self-forwarded");
248 }
249 #endif
250 p += obj->size();
251 }
252 }
253
254 void MutableSpace::print_short() const { print_short_on(tty); }
255 void MutableSpace::print_short_on( outputStream* st) const {
256 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
257 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
258 }
259
260 void MutableSpace::print() const { print_on(tty); }
261 void MutableSpace::print_on(outputStream* st) const {
262 MutableSpace::print_short_on(st);
263 st->print_cr(" [" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT ")",
264 p2i(bottom()), p2i(top()), p2i(end()));
265 }
266
267 void MutableSpace::verify() {
268 HeapWord* p = bottom();
269 HeapWord* t = top();
270 HeapWord* prev_p = nullptr;
271 while (p < t) {
272 oopDesc::verify(cast_to_oop(p));
273 prev_p = p;
274 p += cast_to_oop(p)->size();
275 }
276 guarantee(p == top(), "end of last object must match end of space");
277 }