1 /*
2 * Copyright (c) 2001, 2021, 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/spaceDecorator.hpp"
28 #include "memory/iterator.inline.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/atomic.hpp"
31 #include "runtime/orderAccess.hpp"
32 #include "runtime/safepoint.hpp"
33 #include "runtime/thread.hpp"
34 #include "utilities/align.hpp"
35 #include "utilities/macros.hpp"
36
MutableSpace(size_t alignment)37 MutableSpace::MutableSpace(size_t alignment): ImmutableSpace(), _top(NULL), _alignment(alignment) {
38 assert(MutableSpace::alignment() % os::vm_page_size() == 0,
39 "Space should be aligned");
40 _mangler = new MutableSpaceMangler(this);
41 }
42
~MutableSpace()43 MutableSpace::~MutableSpace() {
44 delete _mangler;
45 }
46
numa_setup_pages(MemRegion mr,bool clear_space)47 void MutableSpace::numa_setup_pages(MemRegion mr, bool clear_space) {
48 if (!mr.is_empty()) {
49 size_t page_size = UseLargePages ? alignment() : os::vm_page_size();
50 HeapWord *start = align_up(mr.start(), page_size);
51 HeapWord *end = align_down(mr.end(), page_size);
52 if (end > start) {
53 size_t size = pointer_delta(end, start, sizeof(char));
54 if (clear_space) {
55 // Prefer page reallocation to migration.
56 os::free_memory((char*)start, size, page_size);
57 }
58 os::numa_make_global((char*)start, size);
59 }
60 }
61 }
62
pretouch_pages(MemRegion mr)63 void MutableSpace::pretouch_pages(MemRegion mr) {
64 os::pretouch_memory(mr.start(), mr.end());
65 }
66
initialize(MemRegion mr,bool clear_space,bool mangle_space,bool setup_pages)67 void MutableSpace::initialize(MemRegion mr,
68 bool clear_space,
69 bool mangle_space,
70 bool setup_pages) {
71
72 assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),
73 "invalid space boundaries");
74
75 if (setup_pages && (UseNUMA || AlwaysPreTouch)) {
76 // The space may move left and right or expand/shrink.
77 // We'd like to enforce the desired page placement.
78 MemRegion head, tail;
79 if (last_setup_region().is_empty()) {
80 // If it's the first initialization don't limit the amount of work.
81 head = mr;
82 tail = MemRegion(mr.end(), mr.end());
83 } else {
84 // Is there an intersection with the address space?
85 MemRegion intersection = last_setup_region().intersection(mr);
86 if (intersection.is_empty()) {
87 intersection = MemRegion(mr.end(), mr.end());
88 }
89 // All the sizes below are in words.
90 size_t head_size = 0, tail_size = 0;
91 if (mr.start() <= intersection.start()) {
92 head_size = pointer_delta(intersection.start(), mr.start());
93 }
94 if(intersection.end() <= mr.end()) {
95 tail_size = pointer_delta(mr.end(), intersection.end());
96 }
97 // Limit the amount of page manipulation if necessary.
98 if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {
99 const size_t change_size = head_size + tail_size;
100 const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;
101 head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),
102 head_size);
103 tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),
104 tail_size);
105 }
106 head = MemRegion(intersection.start() - head_size, intersection.start());
107 tail = MemRegion(intersection.end(), intersection.end() + tail_size);
108 }
109 assert(mr.contains(head) && mr.contains(tail), "Sanity");
110
111 if (UseNUMA) {
112 numa_setup_pages(head, clear_space);
113 numa_setup_pages(tail, clear_space);
114 }
115
116 if (AlwaysPreTouch) {
117 pretouch_pages(head);
118 pretouch_pages(tail);
119 }
120
121 // Remember where we stopped so that we can continue later.
122 set_last_setup_region(MemRegion(head.start(), tail.end()));
123 }
124
125 set_bottom(mr.start());
126 // When expanding concurrently with callers of cas_allocate, setting end
127 // makes the new space available for allocation by other threads. So this
128 // assignment must follow all other configuration and initialization that
129 // might be done for expansion.
130 OrderAccess::release_store(end_addr(), mr.end());
131
132 if (clear_space) {
133 clear(mangle_space);
134 }
135 }
136
clear(bool mangle_space)137 void MutableSpace::clear(bool mangle_space) {
138 set_top(bottom());
139 if (ZapUnusedHeapArea && mangle_space) {
140 mangle_unused_area();
141 }
142 }
143
144 #ifndef PRODUCT
check_mangled_unused_area(HeapWord * limit)145 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
146 mangler()->check_mangled_unused_area(limit);
147 }
148
check_mangled_unused_area_complete()149 void MutableSpace::check_mangled_unused_area_complete() {
150 mangler()->check_mangled_unused_area_complete();
151 }
152
153 // Mangle only the unused space that has not previously
154 // been mangled and that has not been allocated since being
155 // mangled.
mangle_unused_area()156 void MutableSpace::mangle_unused_area() {
157 mangler()->mangle_unused_area();
158 }
159
mangle_unused_area_complete()160 void MutableSpace::mangle_unused_area_complete() {
161 mangler()->mangle_unused_area_complete();
162 }
163
mangle_region(MemRegion mr)164 void MutableSpace::mangle_region(MemRegion mr) {
165 SpaceMangler::mangle_region(mr);
166 }
167
set_top_for_allocations(HeapWord * v)168 void MutableSpace::set_top_for_allocations(HeapWord* v) {
169 mangler()->set_top_for_allocations(v);
170 }
171
set_top_for_allocations()172 void MutableSpace::set_top_for_allocations() {
173 mangler()->set_top_for_allocations(top());
174 }
175 #endif
176
177 // This version requires locking. */
allocate(size_t size)178 HeapWord* MutableSpace::allocate(size_t size) {
179 assert(Heap_lock->owned_by_self() ||
180 (SafepointSynchronize::is_at_safepoint() &&
181 Thread::current()->is_VM_thread()),
182 "not locked");
183 HeapWord* obj = top();
184 if (pointer_delta(end(), obj) >= size) {
185 HeapWord* new_top = obj + size;
186 set_top(new_top);
187 assert(is_object_aligned(obj) && is_object_aligned(new_top),
188 "checking alignment");
189 return obj;
190 } else {
191 return NULL;
192 }
193 }
194
195 // This version is lock-free.
cas_allocate(size_t size)196 HeapWord* MutableSpace::cas_allocate(size_t size) {
197 do {
198 // Read top before end, else the range check may pass when it shouldn't.
199 // If end is read first, other threads may advance end and top such that
200 // current top > old end and current top + size > current end. Then
201 // pointer_delta underflows, allowing installation of top > current end.
202 HeapWord* obj = OrderAccess::load_acquire(top_addr());
203 if (pointer_delta(end(), obj) >= size) {
204 HeapWord* new_top = obj + size;
205 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);
206 // result can be one of two:
207 // the old top value: the exchange succeeded
208 // otherwise: the new value of the top is returned.
209 if (result != obj) {
210 continue; // another thread beat us to the allocation, try again
211 }
212 assert(is_object_aligned(obj) && is_object_aligned(new_top),
213 "checking alignment");
214 return obj;
215 } else {
216 return NULL;
217 }
218 } while (true);
219 }
220
221 // Try to deallocate previous allocation. Returns true upon success.
cas_deallocate(HeapWord * obj,size_t size)222 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
223 HeapWord* expected_top = obj + size;
224 return Atomic::cmpxchg(obj, top_addr(), expected_top) == expected_top;
225 }
226
oop_iterate(OopIterateClosure * cl)227 void MutableSpace::oop_iterate(OopIterateClosure* cl) {
228 HeapWord* obj_addr = bottom();
229 HeapWord* t = top();
230 // Could call objects iterate, but this is easier.
231 while (obj_addr < t) {
232 obj_addr += oop(obj_addr)->oop_iterate_size(cl);
233 }
234 }
235
object_iterate(ObjectClosure * cl)236 void MutableSpace::object_iterate(ObjectClosure* cl) {
237 HeapWord* p = bottom();
238 while (p < top()) {
239 cl->do_object(oop(p));
240 p += oop(p)->size();
241 }
242 }
243
print_short() const244 void MutableSpace::print_short() const { print_short_on(tty); }
print_short_on(outputStream * st) const245 void MutableSpace::print_short_on( outputStream* st) const {
246 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
247 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
248 }
249
print() const250 void MutableSpace::print() const { print_on(tty); }
print_on(outputStream * st) const251 void MutableSpace::print_on(outputStream* st) const {
252 MutableSpace::print_short_on(st);
253 st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
254 p2i(bottom()), p2i(top()), p2i(end()));
255 }
256
verify()257 void MutableSpace::verify() {
258 HeapWord* p = bottom();
259 HeapWord* t = top();
260 HeapWord* prev_p = NULL;
261 while (p < t) {
262 oop(p)->verify();
263 prev_p = p;
264 p += oop(p)->size();
265 }
266 guarantee(p == top(), "end of last object must match end of space");
267 }
268