1 /*
   2  * Copyright (c) 2001, 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 "runtime/atomic.inline.hpp"
  27 #include "utilities/macros.hpp"
  28 #if INCLUDE_ALL_GCS
  29 #include "gc_implementation/shared/mutableSpace.hpp"
  30 #include "gc_implementation/shared/spaceDecorator.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/safepoint.hpp"
  33 #include "runtime/thread.hpp"
  34 #endif // INCLUDE_ALL_GCS
  35 
  36 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  37 
  38 MutableSpace::MutableSpace(size_t alignment): ImmutableSpace(), _top(NULL), _alignment(alignment) {
  39   assert(MutableSpace::alignment() % os::vm_page_size() == 0,
  40          "Space should be aligned");
  41   _mangler = new MutableSpaceMangler(this);
  42 }
  43 
  44 MutableSpace::~MutableSpace() {
  45   delete _mangler;
  46 }
  47 
  48 void MutableSpace::numa_setup_pages(MemRegion mr, bool clear_space) {
  49   if (!mr.is_empty()) {
  50     size_t page_size = UseLargePages ? alignment() : os::vm_page_size();
  51     HeapWord *start = (HeapWord*)round_to((intptr_t) mr.start(), page_size);
  52     HeapWord *end =  (HeapWord*)round_down((intptr_t) mr.end(), page_size);
  53     if (end > start) {
  54       size_t size = pointer_delta(end, start, sizeof(char));
  55       if (clear_space) {
  56         // Prefer page reallocation to migration.
  57         os::free_memory((char*)start, size, page_size);
  58       }
  59       os::numa_make_global((char*)start, size);
  60     }
  61   }
  62 }
  63 
  64 void MutableSpace::pretouch_pages(MemRegion mr) {
  65   os::pretouch_memory((char*)mr.start(), (char*)mr.end());
  66 }
  67 
  68 void MutableSpace::initialize(MemRegion mr,
  69                               bool clear_space,
  70                               bool mangle_space,
  71                               bool setup_pages) {
  72 
  73   assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),
  74          "invalid space boundaries");
  75 
  76   if (setup_pages && (UseNUMA || AlwaysPreTouch)) {
  77     // The space may move left and right or expand/shrink.
  78     // We'd like to enforce the desired page placement.
  79     MemRegion head, tail;
  80     if (last_setup_region().is_empty()) {
  81       // If it's the first initialization don't limit the amount of work.
  82       head = mr;
  83       tail = MemRegion(mr.end(), mr.end());
  84     } else {
  85       // Is there an intersection with the address space?
  86       MemRegion intersection = last_setup_region().intersection(mr);
  87       if (intersection.is_empty()) {
  88         intersection = MemRegion(mr.end(), mr.end());
  89       }
  90       // All the sizes below are in words.
  91       size_t head_size = 0, tail_size = 0;
  92       if (mr.start() <= intersection.start()) {
  93         head_size = pointer_delta(intersection.start(), mr.start());
  94       }
  95       if(intersection.end() <= mr.end()) {
  96         tail_size = pointer_delta(mr.end(), intersection.end());
  97       }
  98       // Limit the amount of page manipulation if necessary.
  99       if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {
 100         const size_t change_size = head_size + tail_size;
 101         const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;
 102         head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),
 103                          head_size);
 104         tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),
 105                          tail_size);
 106       }
 107       head = MemRegion(intersection.start() - head_size, intersection.start());
 108       tail = MemRegion(intersection.end(), intersection.end() + tail_size);
 109     }
 110     assert(mr.contains(head) && mr.contains(tail), "Sanity");
 111 
 112     if (UseNUMA) {
 113       numa_setup_pages(head, clear_space);
 114       numa_setup_pages(tail, clear_space);
 115     }
 116 
 117     if (AlwaysPreTouch) {
 118       pretouch_pages(head);
 119       pretouch_pages(tail);
 120     }
 121 
 122     // Remember where we stopped so that we can continue later.
 123     set_last_setup_region(MemRegion(head.start(), tail.end()));
 124   }
 125 
 126   set_bottom(mr.start());
 127   set_end(mr.end());
 128 
 129   if (clear_space) {
 130     clear(mangle_space);
 131   }
 132 }
 133 
 134 void MutableSpace::clear(bool mangle_space) {
 135   set_top(bottom());
 136   if (ZapUnusedHeapArea && mangle_space) {
 137     mangle_unused_area();
 138   }
 139 }
 140 
 141 #ifndef PRODUCT
 142 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
 143   mangler()->check_mangled_unused_area(limit);
 144 }
 145 
 146 void MutableSpace::check_mangled_unused_area_complete() {
 147   mangler()->check_mangled_unused_area_complete();
 148 }
 149 
 150 // Mangle only the unused space that has not previously
 151 // been mangled and that has not been allocated since being
 152 // mangled.
 153 void MutableSpace::mangle_unused_area() {
 154   mangler()->mangle_unused_area();
 155 }
 156 
 157 void MutableSpace::mangle_unused_area_complete() {
 158   mangler()->mangle_unused_area_complete();
 159 }
 160 
 161 void MutableSpace::mangle_region(MemRegion mr) {
 162   SpaceMangler::mangle_region(mr);
 163 }
 164 
 165 void MutableSpace::set_top_for_allocations(HeapWord* v) {
 166   mangler()->set_top_for_allocations(v);
 167 }
 168 
 169 void MutableSpace::set_top_for_allocations() {
 170   mangler()->set_top_for_allocations(top());
 171 }
 172 #endif
 173 
 174 // This version requires locking. */
 175 HeapWord* MutableSpace::allocate(size_t size) {
 176   assert(Heap_lock->owned_by_self() ||
 177          (SafepointSynchronize::is_at_safepoint() &&
 178           Thread::current()->is_VM_thread()),
 179          "not locked");
 180   HeapWord* obj = top();
 181   if (pointer_delta(end(), obj) >= size) {
 182     HeapWord* new_top = obj + size;
 183     set_top(new_top);
 184     assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
 185            "checking alignment");
 186     return obj;
 187   } else {
 188     return NULL;
 189   }
 190 }
 191 
 192 // This version is lock-free.
 193 HeapWord* MutableSpace::cas_allocate(size_t size) {
 194   do {
 195     HeapWord* obj = top();
 196     if (pointer_delta(end(), obj) >= size) {
 197       HeapWord* new_top = obj + size;
 198       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
 199       // result can be one of two:
 200       //  the old top value: the exchange succeeded
 201       //  otherwise: the new value of the top is returned.
 202       if (result != obj) {
 203         continue; // another thread beat us to the allocation, try again
 204       }
 205       assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
 206              "checking alignment");
 207       return obj;
 208     } else {
 209       return NULL;
 210     }
 211   } while (true);
 212 }
 213 
 214 // Try to deallocate previous allocation. Returns true upon success.
 215 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
 216   HeapWord* expected_top = obj + size;
 217   return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
 218 }
 219 
 220 void MutableSpace::oop_iterate(ExtendedOopClosure* cl) {
 221   HeapWord* obj_addr = bottom();
 222   HeapWord* t = top();
 223   // Could call objects iterate, but this is easier.
 224   while (obj_addr < t) {
 225     obj_addr += oop(obj_addr)->oop_iterate(cl);
 226   }
 227 }
 228 
 229 void MutableSpace::oop_iterate_no_header(OopClosure* cl) {
 230   HeapWord* obj_addr = bottom();
 231   HeapWord* t = top();
 232   // Could call objects iterate, but this is easier.
 233   while (obj_addr < t) {
 234     obj_addr += oop(obj_addr)->oop_iterate_no_header(cl);
 235   }
 236 }
 237 
 238 void MutableSpace::object_iterate(ObjectClosure* cl) {
 239   HeapWord* p = bottom();
 240   while (p < top()) {
 241     cl->do_object(oop(p));
 242     p += oop(p)->size();
 243   }
 244 }
 245 
 246 void MutableSpace::print_short() const { print_short_on(tty); }
 247 void MutableSpace::print_short_on( outputStream* st) const {
 248   st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
 249             (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
 250 }
 251 
 252 void MutableSpace::print() const { print_on(tty); }
 253 void MutableSpace::print_on(outputStream* st) const {
 254   MutableSpace::print_short_on(st);
 255   st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
 256                  bottom(), top(), end());
 257 }
 258 
 259 void MutableSpace::verify() {
 260   HeapWord* p = bottom();
 261   HeapWord* t = top();
 262   HeapWord* prev_p = NULL;
 263   while (p < t) {
 264     oop(p)->verify();
 265     prev_p = p;
 266     p += oop(p)->size();
 267   }
 268   guarantee(p == top(), "end of last object must match end of space");
 269 }