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