1 /*
   2  * Copyright (c) 2005, 2016, 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/parMarkBitMap.inline.hpp"
  27 #include "gc/parallel/psCompactionManager.inline.hpp"
  28 #include "gc/parallel/psParallelCompact.inline.hpp"
  29 #include "oops/oop.inline.hpp"
  30 #include "runtime/atomic.hpp"
  31 #include "runtime/os.hpp"
  32 #include "services/memTracker.hpp"
  33 #include "utilities/bitMap.inline.hpp"
  34 
  35 bool
  36 ParMarkBitMap::initialize(MemRegion covered_region)
  37 {
  38   const idx_t bits = bits_required(covered_region);
  39   // The bits will be divided evenly between two bitmaps; each of them should be
  40   // an integral number of words.
  41   assert(bits % (BitsPerWord * 2) == 0, "region size unaligned");
  42 
  43   const size_t words = bits / BitsPerWord;
  44   const size_t raw_bytes = words * sizeof(idx_t);
  45   const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
  46   const size_t granularity = os::vm_allocation_granularity();
  47   _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
  48 
  49   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
  50     MAX2(page_sz, granularity);
  51   ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
  52   os::trace_page_sizes("Mark Bitmap", raw_bytes, raw_bytes, page_sz,
  53                        rs.base(), rs.size());
  54 
  55   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
  56 
  57   _virtual_space = new PSVirtualSpace(rs, page_sz);
  58   if (_virtual_space != NULL && _virtual_space->expand_by(_reserved_byte_size)) {
  59     _region_start = covered_region.start();
  60     _region_size = covered_region.word_size();
  61     BitMap::bm_word_t* map = (BitMap::bm_word_t*)_virtual_space->reserved_low_addr();
  62     _beg_bits = BitMapView(map,             bits / 2);
  63     _end_bits = BitMapView(map + words / 2, bits / 2);
  64     return true;
  65   }
  66 
  67   _region_start = 0;
  68   _region_size = 0;
  69   if (_virtual_space != NULL) {
  70     delete _virtual_space;
  71     _virtual_space = NULL;
  72     // Release memory reserved in the space.
  73     rs.release();
  74   }
  75   return false;
  76 }
  77 
  78 #ifdef ASSERT
  79 extern size_t mark_bitmap_count;
  80 extern size_t mark_bitmap_size;
  81 #endif  // #ifdef ASSERT
  82 
  83 bool
  84 ParMarkBitMap::mark_obj(HeapWord* addr, size_t size)
  85 {
  86   const idx_t beg_bit = addr_to_bit(addr);
  87   if (_beg_bits.par_set_bit(beg_bit)) {
  88     const idx_t end_bit = addr_to_bit(addr + size - 1);
  89     bool end_bit_ok = _end_bits.par_set_bit(end_bit);
  90     assert(end_bit_ok, "concurrency problem");
  91     DEBUG_ONLY(Atomic::inc_ptr(&mark_bitmap_count));
  92     DEBUG_ONLY(Atomic::add_ptr(size, &mark_bitmap_size));
  93     return true;
  94   }
  95   return false;
  96 }
  97 
  98 inline bool
  99 ParMarkBitMap::is_live_words_in_range_in_cache(ParCompactionManager* cm, HeapWord* beg_addr) const {
 100   return cm->last_query_begin() == beg_addr;
 101 }
 102 
 103 inline void
 104 ParMarkBitMap::update_live_words_in_range_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj, size_t result) const {
 105   cm->set_last_query_begin(beg_addr);
 106   cm->set_last_query_object(end_obj);
 107   cm->set_last_query_return(result);
 108 }
 109 
 110 size_t
 111 ParMarkBitMap::live_words_in_range_helper(HeapWord* beg_addr, oop end_obj) const
 112 {
 113   assert(beg_addr <= (HeapWord*)end_obj, "bad range");
 114   assert(is_marked(end_obj), "end_obj must be live");
 115 
 116   idx_t live_bits = 0;
 117 
 118   // The bitmap routines require the right boundary to be word-aligned.
 119   const idx_t end_bit = addr_to_bit((HeapWord*)end_obj);
 120   const idx_t range_end = BitMap::word_align_up(end_bit);
 121 
 122   idx_t beg_bit = find_obj_beg(addr_to_bit(beg_addr), range_end);
 123   while (beg_bit < end_bit) {
 124     idx_t tmp_end = find_obj_end(beg_bit, range_end);
 125     assert(tmp_end < end_bit, "missing end bit");
 126     live_bits += tmp_end - beg_bit + 1;
 127     beg_bit = find_obj_beg(tmp_end + 1, range_end);
 128   }
 129   return bits_to_words(live_bits);
 130 }
 131 
 132 size_t
 133 ParMarkBitMap::live_words_in_range_use_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const
 134 {
 135   HeapWord* last_beg = cm->last_query_begin();
 136   oop last_obj = cm->last_query_object();
 137   size_t last_ret = cm->last_query_return();
 138   if (end_obj > last_obj) {
 139     last_ret = last_ret + live_words_in_range_helper((HeapWord*)last_obj, end_obj);
 140     last_obj = end_obj;
 141   } else if (end_obj < last_obj) {
 142     // The cached value is for an object that is to the left (lower address) of the current
 143     // end_obj. Calculate back from that cached value.
 144     if (pointer_delta((HeapWord*)end_obj, (HeapWord*)beg_addr) > pointer_delta((HeapWord*)last_obj, (HeapWord*)end_obj)) {
 145       last_ret = last_ret - live_words_in_range_helper((HeapWord*)end_obj, last_obj);
 146     } else {
 147       last_ret = live_words_in_range_helper(beg_addr, end_obj);
 148     }
 149     last_obj = end_obj;
 150   }
 151 
 152   update_live_words_in_range_cache(cm, last_beg, last_obj, last_ret);
 153   return last_ret;
 154 }
 155 
 156 size_t
 157 ParMarkBitMap::live_words_in_range(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const
 158 {
 159   // Try to reuse result from ParCompactionManager cache first.
 160   if (is_live_words_in_range_in_cache(cm, beg_addr)) {
 161     return live_words_in_range_use_cache(cm, beg_addr, end_obj);
 162   }
 163   size_t ret = live_words_in_range_helper(beg_addr, end_obj);
 164   update_live_words_in_range_cache(cm, beg_addr, end_obj, ret);
 165   return ret;
 166 }
 167 
 168 ParMarkBitMap::IterationStatus
 169 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
 170                        idx_t range_beg, idx_t range_end) const
 171 {
 172   DEBUG_ONLY(verify_bit(range_beg);)
 173   DEBUG_ONLY(verify_bit(range_end);)
 174   assert(range_beg <= range_end, "live range invalid");
 175 
 176   // The bitmap routines require the right boundary to be word-aligned.
 177   const idx_t search_end = BitMap::word_align_up(range_end);
 178 
 179   idx_t cur_beg = find_obj_beg(range_beg, search_end);
 180   while (cur_beg < range_end) {
 181     const idx_t cur_end = find_obj_end(cur_beg, search_end);
 182     if (cur_end >= range_end) {
 183       // The obj ends outside the range.
 184       live_closure->set_source(bit_to_addr(cur_beg));
 185       return incomplete;
 186     }
 187 
 188     const size_t size = obj_size(cur_beg, cur_end);
 189     IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
 190     if (status != incomplete) {
 191       assert(status == would_overflow || status == full, "sanity");
 192       return status;
 193     }
 194 
 195     // Successfully processed the object; look for the next object.
 196     cur_beg = find_obj_beg(cur_end + 1, search_end);
 197   }
 198 
 199   live_closure->set_source(bit_to_addr(range_end));
 200   return complete;
 201 }
 202 
 203 ParMarkBitMap::IterationStatus
 204 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
 205                        ParMarkBitMapClosure* dead_closure,
 206                        idx_t range_beg, idx_t range_end,
 207                        idx_t dead_range_end) const
 208 {
 209   DEBUG_ONLY(verify_bit(range_beg);)
 210   DEBUG_ONLY(verify_bit(range_end);)
 211   DEBUG_ONLY(verify_bit(dead_range_end);)
 212   assert(range_beg <= range_end, "live range invalid");
 213   assert(range_end <= dead_range_end, "dead range invalid");
 214 
 215   // The bitmap routines require the right boundary to be word-aligned.
 216   const idx_t live_search_end = BitMap::word_align_up(range_end);
 217   const idx_t dead_search_end = BitMap::word_align_up(dead_range_end);
 218 
 219   idx_t cur_beg = range_beg;
 220   if (range_beg < range_end && is_unmarked(range_beg)) {
 221     // The range starts with dead space.  Look for the next object, then fill.
 222     cur_beg = find_obj_beg(range_beg + 1, dead_search_end);
 223     const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
 224     const size_t size = obj_size(range_beg, dead_space_end);
 225     dead_closure->do_addr(bit_to_addr(range_beg), size);
 226   }
 227 
 228   while (cur_beg < range_end) {
 229     const idx_t cur_end = find_obj_end(cur_beg, live_search_end);
 230     if (cur_end >= range_end) {
 231       // The obj ends outside the range.
 232       live_closure->set_source(bit_to_addr(cur_beg));
 233       return incomplete;
 234     }
 235 
 236     const size_t size = obj_size(cur_beg, cur_end);
 237     IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
 238     if (status != incomplete) {
 239       assert(status == would_overflow || status == full, "sanity");
 240       return status;
 241     }
 242 
 243     // Look for the start of the next object.
 244     const idx_t dead_space_beg = cur_end + 1;
 245     cur_beg = find_obj_beg(dead_space_beg, dead_search_end);
 246     if (cur_beg > dead_space_beg) {
 247       // Found dead space; compute the size and invoke the dead closure.
 248       const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
 249       const size_t size = obj_size(dead_space_beg, dead_space_end);
 250       dead_closure->do_addr(bit_to_addr(dead_space_beg), size);
 251     }
 252   }
 253 
 254   live_closure->set_source(bit_to_addr(range_end));
 255   return complete;
 256 }
 257 
 258 #ifdef ASSERT
 259 void ParMarkBitMap::verify_clear() const
 260 {
 261   const idx_t* const beg = (const idx_t*)_virtual_space->committed_low_addr();
 262   const idx_t* const end = (const idx_t*)_virtual_space->committed_high_addr();
 263   for (const idx_t* p = beg; p < end; ++p) {
 264     assert(*p == 0, "bitmap not clear");
 265   }
 266 }
 267 #endif  // #ifdef ASSERT