1 /*
2 * Copyright (c) 2001, 2009, 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 "incls/_precompiled.incl"
26 # include "incls/_mutableSpace.cpp.incl"
27
28 MutableSpace::MutableSpace(size_t alignment): ImmutableSpace(), _top(NULL), _alignment(alignment) {
29 assert(MutableSpace::alignment() >= 0 &&
30 MutableSpace::alignment() % os::vm_page_size() == 0,
31 "Space should be aligned");
32 _mangler = new MutableSpaceMangler(this);
33 }
34
35 MutableSpace::~MutableSpace() {
36 delete _mangler;
37 }
38
39 void MutableSpace::numa_setup_pages(MemRegion mr, bool clear_space) {
40 if (!mr.is_empty()) {
41 size_t page_size = UseLargePages ? alignment() : os::vm_page_size();
42 HeapWord *start = (HeapWord*)round_to((intptr_t) mr.start(), page_size);
43 HeapWord *end = (HeapWord*)round_down((intptr_t) mr.end(), page_size);
44 if (end > start) {
45 size_t size = pointer_delta(end, start, sizeof(char));
46 if (clear_space) {
47 // Prefer page reallocation to migration.
48 os::free_memory((char*)start, size);
49 }
50 os::numa_make_global((char*)start, size);
51 }
52 }
53 }
54
55 void MutableSpace::pretouch_pages(MemRegion mr) {
56 for (volatile char *p = (char*)mr.start(); p < (char*)mr.end(); p += os::vm_page_size()) {
57 char t = *p; *p = t;
58 }
59 }
60
61 void MutableSpace::initialize(MemRegion mr,
62 bool clear_space,
63 bool mangle_space,
64 bool setup_pages) {
65
66 assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),
67 "invalid space boundaries");
68
69 if (setup_pages && (UseNUMA || AlwaysPreTouch)) {
70 // The space may move left and right or expand/shrink.
71 // We'd like to enforce the desired page placement.
72 MemRegion head, tail;
73 if (last_setup_region().is_empty()) {
74 // If it's the first initialization don't limit the amount of work.
75 head = mr;
76 tail = MemRegion(mr.end(), mr.end());
77 } else {
78 // Is there an intersection with the address space?
79 MemRegion intersection = last_setup_region().intersection(mr);
80 if (intersection.is_empty()) {
81 intersection = MemRegion(mr.end(), mr.end());
82 }
83 // All the sizes below are in words.
84 size_t head_size = 0, tail_size = 0;
85 if (mr.start() <= intersection.start()) {
86 head_size = pointer_delta(intersection.start(), mr.start());
87 }
88 if(intersection.end() <= mr.end()) {
89 tail_size = pointer_delta(mr.end(), intersection.end());
90 }
91 // Limit the amount of page manipulation if necessary.
92 if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {
93 const size_t change_size = head_size + tail_size;
94 const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;
95 head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),
96 head_size);
97 tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),
98 tail_size);
99 }
100 head = MemRegion(intersection.start() - head_size, intersection.start());
101 tail = MemRegion(intersection.end(), intersection.end() + tail_size);
102 }
103 assert(mr.contains(head) && mr.contains(tail), "Sanity");
104
105 if (UseNUMA) {
106 numa_setup_pages(head, clear_space);
107 numa_setup_pages(tail, clear_space);
108 }
109
110 if (AlwaysPreTouch) {
111 pretouch_pages(head);
112 pretouch_pages(tail);
113 }
114
115 // Remember where we stopped so that we can continue later.
116 set_last_setup_region(MemRegion(head.start(), tail.end()));
117 }
118
119 set_bottom(mr.start());
120 set_end(mr.end());
121
122 if (clear_space) {
123 clear(mangle_space);
124 }
125 }
126
127 void MutableSpace::clear(bool mangle_space) {
128 set_top(bottom());
129 if (ZapUnusedHeapArea && mangle_space) {
130 mangle_unused_area();
131 }
132 }
133
134 #ifndef PRODUCT
135 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
136 mangler()->check_mangled_unused_area(limit);
137 }
138
139 void MutableSpace::check_mangled_unused_area_complete() {
140 mangler()->check_mangled_unused_area_complete();
141 }
142
143 // Mangle only the unused space that has not previously
144 // been mangled and that has not been allocated since being
145 // mangled.
146 void MutableSpace::mangle_unused_area() {
147 mangler()->mangle_unused_area();
148 }
149
150 void MutableSpace::mangle_unused_area_complete() {
151 mangler()->mangle_unused_area_complete();
152 }
153
154 void MutableSpace::mangle_region(MemRegion mr) {
155 SpaceMangler::mangle_region(mr);
156 }
157
158 void MutableSpace::set_top_for_allocations(HeapWord* v) {
159 mangler()->set_top_for_allocations(v);
160 }
161
162 void MutableSpace::set_top_for_allocations() {
163 mangler()->set_top_for_allocations(top());
164 }
165 #endif
166
167 // This version requires locking. */
168 HeapWord* MutableSpace::allocate(size_t size) {
169 assert(Heap_lock->owned_by_self() ||
170 (SafepointSynchronize::is_at_safepoint() &&
171 Thread::current()->is_VM_thread()),
172 "not locked");
173 HeapWord* obj = top();
174 if (pointer_delta(end(), obj) >= size) {
175 HeapWord* new_top = obj + size;
176 set_top(new_top);
177 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
178 "checking alignment");
179 return obj;
180 } else {
181 return NULL;
182 }
183 }
184
185 // This version is lock-free.
186 HeapWord* MutableSpace::cas_allocate(size_t size) {
187 do {
188 HeapWord* obj = top();
189 if (pointer_delta(end(), obj) >= size) {
190 HeapWord* new_top = obj + size;
191 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
192 // result can be one of two:
193 // the old top value: the exchange succeeded
194 // otherwise: the new value of the top is returned.
195 if (result != obj) {
196 continue; // another thread beat us to the allocation, try again
197 }
198 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
199 "checking alignment");
200 return obj;
201 } else {
202 return NULL;
203 }
204 } while (true);
205 }
206
207 // Try to deallocate previous allocation. Returns true upon success.
208 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
209 HeapWord* expected_top = obj + size;
210 return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
211 }
212
213 void MutableSpace::oop_iterate(OopClosure* cl) {
214 HeapWord* obj_addr = bottom();
215 HeapWord* t = top();
216 // Could call objects iterate, but this is easier.
217 while (obj_addr < t) {
218 obj_addr += oop(obj_addr)->oop_iterate(cl);
219 }
220 }
221
222 void MutableSpace::object_iterate(ObjectClosure* cl) {
223 HeapWord* p = bottom();
224 while (p < top()) {
225 cl->do_object(oop(p));
226 p += oop(p)->size();
227 }
228 }
229
230 void MutableSpace::print_short() const { print_short_on(tty); }
231 void MutableSpace::print_short_on( outputStream* st) const {
232 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
233 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
234 }
235
236 void MutableSpace::print() const { print_on(tty); }
237 void MutableSpace::print_on(outputStream* st) const {
238 MutableSpace::print_short_on(st);
239 st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
240 bottom(), top(), end());
241 }
242
243 void MutableSpace::verify(bool allow_dirty) {
244 HeapWord* p = bottom();
245 HeapWord* t = top();
246 HeapWord* prev_p = NULL;
247 while (p < t) {
248 oop(p)->verify();
249 prev_p = p;
250 p += oop(p)->size();
251 }
252 guarantee(p == top(), "end of last object must match end of space");
253 }