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() >= 0 &&
  40          MutableSpace::alignment() % os::vm_page_size() == 0,
  41          "Space should be aligned");
  42   _mangler = new MutableSpaceMangler(this);
  43 }
  44 
  45 MutableSpace::~MutableSpace() {
  46   delete _mangler;
  47 }
  48 
  49 void MutableSpace::numa_setup_pages(MemRegion mr, bool clear_space) {
  50   if (!mr.is_empty()) {
  51     size_t page_size = UseLargePages ? alignment() : os::vm_page_size();
  52     HeapWord *start = (HeapWord*)round_to((intptr_t) mr.start(), page_size);
  53     HeapWord *end =  (HeapWord*)round_down((intptr_t) mr.end(), page_size);
  54     if (end > start) {
  55       size_t size = pointer_delta(end, start, sizeof(char));
  56       if (clear_space) {
  57         // Prefer page reallocation to migration.
  58         os::free_memory((char*)start, size, page_size);
  59       }
  60       os::numa_make_global((char*)start, size);
  61     }
  62   }
  63 }
  64 
  65 void MutableSpace::pretouch_pages(MemRegion mr) {
  66   os::pretouch_memory((char*)mr.start(), (char*)mr.end());
  67 }
  68 
  69 void MutableSpace::initialize(MemRegion mr,
  70                               bool clear_space,
  71                               bool mangle_space,
  72                               bool setup_pages) {
  73 
  74   assert(Universe::on_page_boundary(mr.start()) && Universe::on_page_boundary(mr.end()),
  75          "invalid space boundaries");
  76 
  77   if (setup_pages && (UseNUMA || AlwaysPreTouch)) {
  78     // The space may move left and right or expand/shrink.
  79     // We'd like to enforce the desired page placement.
  80     MemRegion head, tail;
  81     if (last_setup_region().is_empty()) {
  82       // If it's the first initialization don't limit the amount of work.
  83       head = mr;
  84       tail = MemRegion(mr.end(), mr.end());
  85     } else {
  86       // Is there an intersection with the address space?
  87       MemRegion intersection = last_setup_region().intersection(mr);
  88       if (intersection.is_empty()) {
  89         intersection = MemRegion(mr.end(), mr.end());
  90       }
  91       // All the sizes below are in words.
  92       size_t head_size = 0, tail_size = 0;
  93       if (mr.start() <= intersection.start()) {
  94         head_size = pointer_delta(intersection.start(), mr.start());
  95       }
  96       if(intersection.end() <= mr.end()) {
  97         tail_size = pointer_delta(mr.end(), intersection.end());
  98       }
  99       // Limit the amount of page manipulation if necessary.
 100       if (NUMASpaceResizeRate > 0 && !AlwaysPreTouch) {
 101         const size_t change_size = head_size + tail_size;
 102         const float setup_rate_words = NUMASpaceResizeRate >> LogBytesPerWord;
 103         head_size = MIN2((size_t)(setup_rate_words * head_size / change_size),
 104                          head_size);
 105         tail_size = MIN2((size_t)(setup_rate_words * tail_size / change_size),
 106                          tail_size);
 107       }
 108       head = MemRegion(intersection.start() - head_size, intersection.start());
 109       tail = MemRegion(intersection.end(), intersection.end() + tail_size);
 110     }
 111     assert(mr.contains(head) && mr.contains(tail), "Sanity");
 112 
 113     if (UseNUMA) {
 114       numa_setup_pages(head, clear_space);
 115       numa_setup_pages(tail, clear_space);
 116     }
 117 
 118     if (AlwaysPreTouch) {
 119       pretouch_pages(head);
 120       pretouch_pages(tail);
 121     }
 122 
 123     // Remember where we stopped so that we can continue later.
 124     set_last_setup_region(MemRegion(head.start(), tail.end()));
 125   }
 126 
 127   set_bottom(mr.start());
 128   set_end(mr.end());
 129 
 130   if (clear_space) {
 131     clear(mangle_space);
 132   }
 133 }
 134 
 135 void MutableSpace::clear(bool mangle_space) {
 136   set_top(bottom());
 137   if (ZapUnusedHeapArea && mangle_space) {
 138     mangle_unused_area();
 139   }
 140 }
 141 
 142 #ifndef PRODUCT
 143 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
 144   mangler()->check_mangled_unused_area(limit);
 145 }
 146 
 147 void MutableSpace::check_mangled_unused_area_complete() {
 148   mangler()->check_mangled_unused_area_complete();
 149 }
 150 
 151 // Mangle only the unused space that has not previously
 152 // been mangled and that has not been allocated since being
 153 // mangled.
 154 void MutableSpace::mangle_unused_area() {
 155   mangler()->mangle_unused_area();
 156 }
 157 
 158 void MutableSpace::mangle_unused_area_complete() {
 159   mangler()->mangle_unused_area_complete();
 160 }
 161 
 162 void MutableSpace::mangle_region(MemRegion mr) {
 163   SpaceMangler::mangle_region(mr);
 164 }
 165 
 166 void MutableSpace::set_top_for_allocations(HeapWord* v) {
 167   mangler()->set_top_for_allocations(v);
 168 }
 169 
 170 void MutableSpace::set_top_for_allocations() {
 171   mangler()->set_top_for_allocations(top());
 172 }
 173 #endif
 174 
 175 // This version requires locking. */
 176 HeapWord* MutableSpace::allocate(size_t size) {
 177   assert(Heap_lock->owned_by_self() ||
 178          (SafepointSynchronize::is_at_safepoint() &&
 179           Thread::current()->is_VM_thread()),
 180          "not locked");
 181   HeapWord* obj = top();
 182   if (pointer_delta(end(), obj) >= size) {
 183     HeapWord* new_top = obj + size;
 184     set_top(new_top);
 185     assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
 186            "checking alignment");
 187     return obj;
 188   } else {
 189     return NULL;
 190   }
 191 }
 192 
 193 // This version is lock-free.
 194 HeapWord* MutableSpace::cas_allocate(size_t size) {
 195   do {
 196     HeapWord* obj = top();
 197     if (pointer_delta(end(), obj) >= size) {
 198       HeapWord* new_top = obj + size;
 199       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
 200       // result can be one of two:
 201       //  the old top value: the exchange succeeded
 202       //  otherwise: the new value of the top is returned.
 203       if (result != obj) {
 204         continue; // another thread beat us to the allocation, try again
 205       }
 206       assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
 207              "checking alignment");
 208       return obj;
 209     } else {
 210       return NULL;
 211     }
 212   } while (true);
 213 }
 214 
 215 // Try to deallocate previous allocation. Returns true upon success.
 216 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
 217   HeapWord* expected_top = obj + size;
 218   return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
 219 }
 220 
 221 void MutableSpace::oop_iterate(ExtendedOopClosure* cl) {
 222   HeapWord* obj_addr = bottom();
 223   HeapWord* t = top();
 224   // Could call objects iterate, but this is easier.
 225   while (obj_addr < t) {
 226     obj_addr += oop(obj_addr)->oop_iterate(cl);
 227   }
 228 }
 229 
 230 void MutableSpace::oop_iterate_no_header(OopClosure* cl) {
 231   HeapWord* obj_addr = bottom();
 232   HeapWord* t = top();
 233   // Could call objects iterate, but this is easier.
 234   while (obj_addr < t) {
 235     obj_addr += oop(obj_addr)->oop_iterate_no_header(cl);
 236   }
 237 }
 238 
 239 void MutableSpace::object_iterate(ObjectClosure* cl) {
 240   HeapWord* p = bottom();
 241   while (p < top()) {
 242     cl->do_object(oop(p));
 243     p += oop(p)->size();
 244   }
 245 }
 246 
 247 void MutableSpace::print_short() const { print_short_on(tty); }
 248 void MutableSpace::print_short_on( outputStream* st) const {
 249   st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
 250             (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
 251 }
 252 
 253 void MutableSpace::print() const { print_on(tty); }
 254 void MutableSpace::print_on(outputStream* st) const {
 255   MutableSpace::print_short_on(st);
 256   st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
 257                  bottom(), top(), end());
 258 }
 259 
 260 void MutableSpace::verify() {
 261   HeapWord* p = bottom();
 262   HeapWord* t = top();
 263   HeapWord* prev_p = NULL;
 264   while (p < t) {
 265     oop(p)->verify();
 266     prev_p = p;
 267     p += oop(p)->size();
 268   }
 269   guarantee(p == top(), "end of last object must match end of space");
 270 }