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/align.hpp"
34#include "utilities/bitMap.inline.hpp"
35
36bool
37ParMarkBitMap::initialize(MemRegion covered_region)
38{
39  const idx_t bits = bits_required(covered_region);
40  // The bits will be divided evenly between two bitmaps; each of them should be
41  // an integral number of words.
42  assert(bits % (BitsPerWord * 2) == 0, "region size unaligned");
43
44  const size_t words = bits / BitsPerWord;
45  const size_t raw_bytes = words * sizeof(idx_t);
46  const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
47  const size_t granularity = os::vm_allocation_granularity();
48  _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
49
50  const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
51    MAX2(page_sz, granularity);
52  ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
53  os::trace_page_sizes("Mark Bitmap", raw_bytes, raw_bytes, page_sz,
54                       rs.base(), rs.size());
55
56  MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
57
58  _virtual_space = new PSVirtualSpace(rs, page_sz);
59  if (_virtual_space != NULL && _virtual_space->expand_by(_reserved_byte_size)) {
60    _region_start = covered_region.start();
61    _region_size = covered_region.word_size();
62    BitMap::bm_word_t* map = (BitMap::bm_word_t*)_virtual_space->reserved_low_addr();
63    _beg_bits = BitMapView(map,             bits / 2);
64    _end_bits = BitMapView(map + words / 2, bits / 2);
65    return true;
66  }
67
68  _region_start = 0;
69  _region_size = 0;
70  if (_virtual_space != NULL) {
71    delete _virtual_space;
72    _virtual_space = NULL;
73    // Release memory reserved in the space.
74    rs.release();
75  }
76  return false;
77}
78
79#ifdef ASSERT
80extern size_t mark_bitmap_count;
81extern size_t mark_bitmap_size;
82#endif  // #ifdef ASSERT
83
84bool
85ParMarkBitMap::mark_obj(HeapWord* addr, size_t size)
86{
87  const idx_t beg_bit = addr_to_bit(addr);
88  if (_beg_bits.par_set_bit(beg_bit)) {
89    const idx_t end_bit = addr_to_bit(addr + size - 1);
90    bool end_bit_ok = _end_bits.par_set_bit(end_bit);
91    assert(end_bit_ok, "concurrency problem");
92    DEBUG_ONLY(Atomic::inc_ptr(&mark_bitmap_count));
93    DEBUG_ONLY(Atomic::add_ptr(size, &mark_bitmap_size));
94    return true;
95  }
96  return false;
97}
98
99inline bool
100ParMarkBitMap::is_live_words_in_range_in_cache(ParCompactionManager* cm, HeapWord* beg_addr) const {
101  return cm->last_query_begin() == beg_addr;
102}
103
104inline void
105ParMarkBitMap::update_live_words_in_range_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj, size_t result) const {
106  cm->set_last_query_begin(beg_addr);
107  cm->set_last_query_object(end_obj);
108  cm->set_last_query_return(result);
109}
110
111size_t
112ParMarkBitMap::live_words_in_range_helper(HeapWord* beg_addr, oop end_obj) const
113{
114  assert(beg_addr <= (HeapWord*)end_obj, "bad range");
115  assert(is_marked(end_obj), "end_obj must be live");
116
117  idx_t live_bits = 0;
118
119  // The bitmap routines require the right boundary to be word-aligned.
120  const idx_t end_bit = addr_to_bit((HeapWord*)end_obj);
121  const idx_t range_end = BitMap::word_align_up(end_bit);
122
123  idx_t beg_bit = find_obj_beg(addr_to_bit(beg_addr), range_end);
124  while (beg_bit < end_bit) {
125    idx_t tmp_end = find_obj_end(beg_bit, range_end);
126    assert(tmp_end < end_bit, "missing end bit");
127    live_bits += tmp_end - beg_bit + 1;
128    beg_bit = find_obj_beg(tmp_end + 1, range_end);
129  }
130  return bits_to_words(live_bits);
131}
132
133size_t
134ParMarkBitMap::live_words_in_range_use_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const
135{
136  HeapWord* last_beg = cm->last_query_begin();
137  oop last_obj = cm->last_query_object();
138  size_t last_ret = cm->last_query_return();
139  if (end_obj > last_obj) {
140    last_ret = last_ret + live_words_in_range_helper((HeapWord*)last_obj, end_obj);
141    last_obj = end_obj;
142  } else if (end_obj < last_obj) {
143    // The cached value is for an object that is to the left (lower address) of the current
144    // end_obj. Calculate back from that cached value.
145    if (pointer_delta((HeapWord*)end_obj, (HeapWord*)beg_addr) > pointer_delta((HeapWord*)last_obj, (HeapWord*)end_obj)) {
146      last_ret = last_ret - live_words_in_range_helper((HeapWord*)end_obj, last_obj);
147    } else {
148      last_ret = live_words_in_range_helper(beg_addr, end_obj);
149    }
150    last_obj = end_obj;
151  }
152
153  update_live_words_in_range_cache(cm, last_beg, last_obj, last_ret);
154  return last_ret;
155}
156
157size_t
158ParMarkBitMap::live_words_in_range(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const
159{
160  // Try to reuse result from ParCompactionManager cache first.
161  if (is_live_words_in_range_in_cache(cm, beg_addr)) {
162    return live_words_in_range_use_cache(cm, beg_addr, end_obj);
163  }
164  size_t ret = live_words_in_range_helper(beg_addr, end_obj);
165  update_live_words_in_range_cache(cm, beg_addr, end_obj, ret);
166  return ret;
167}
168
169ParMarkBitMap::IterationStatus
170ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
171                       idx_t range_beg, idx_t range_end) const
172{
173  DEBUG_ONLY(verify_bit(range_beg);)
174  DEBUG_ONLY(verify_bit(range_end);)
175  assert(range_beg <= range_end, "live range invalid");
176
177  // The bitmap routines require the right boundary to be word-aligned.
178  const idx_t search_end = BitMap::word_align_up(range_end);
179
180  idx_t cur_beg = find_obj_beg(range_beg, search_end);
181  while (cur_beg < range_end) {
182    const idx_t cur_end = find_obj_end(cur_beg, search_end);
183    if (cur_end >= range_end) {
184      // The obj ends outside the range.
185      live_closure->set_source(bit_to_addr(cur_beg));
186      return incomplete;
187    }
188
189    const size_t size = obj_size(cur_beg, cur_end);
190    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
191    if (status != incomplete) {
192      assert(status == would_overflow || status == full, "sanity");
193      return status;
194    }
195
196    // Successfully processed the object; look for the next object.
197    cur_beg = find_obj_beg(cur_end + 1, search_end);
198  }
199
200  live_closure->set_source(bit_to_addr(range_end));
201  return complete;
202}
203
204ParMarkBitMap::IterationStatus
205ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
206                       ParMarkBitMapClosure* dead_closure,
207                       idx_t range_beg, idx_t range_end,
208                       idx_t dead_range_end) const
209{
210  DEBUG_ONLY(verify_bit(range_beg);)
211  DEBUG_ONLY(verify_bit(range_end);)
212  DEBUG_ONLY(verify_bit(dead_range_end);)
213  assert(range_beg <= range_end, "live range invalid");
214  assert(range_end <= dead_range_end, "dead range invalid");
215
216  // The bitmap routines require the right boundary to be word-aligned.
217  const idx_t live_search_end = BitMap::word_align_up(range_end);
218  const idx_t dead_search_end = BitMap::word_align_up(dead_range_end);
219
220  idx_t cur_beg = range_beg;
221  if (range_beg < range_end && is_unmarked(range_beg)) {
222    // The range starts with dead space.  Look for the next object, then fill.
223    cur_beg = find_obj_beg(range_beg + 1, dead_search_end);
224    const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
225    const size_t size = obj_size(range_beg, dead_space_end);
226    dead_closure->do_addr(bit_to_addr(range_beg), size);
227  }
228
229  while (cur_beg < range_end) {
230    const idx_t cur_end = find_obj_end(cur_beg, live_search_end);
231    if (cur_end >= range_end) {
232      // The obj ends outside the range.
233      live_closure->set_source(bit_to_addr(cur_beg));
234      return incomplete;
235    }
236
237    const size_t size = obj_size(cur_beg, cur_end);
238    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);
239    if (status != incomplete) {
240      assert(status == would_overflow || status == full, "sanity");
241      return status;
242    }
243
244    // Look for the start of the next object.
245    const idx_t dead_space_beg = cur_end + 1;
246    cur_beg = find_obj_beg(dead_space_beg, dead_search_end);
247    if (cur_beg > dead_space_beg) {
248      // Found dead space; compute the size and invoke the dead closure.
249      const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);
250      const size_t size = obj_size(dead_space_beg, dead_space_end);
251      dead_closure->do_addr(bit_to_addr(dead_space_beg), size);
252    }
253  }
254
255  live_closure->set_source(bit_to_addr(range_end));
256  return complete;
257}
258
259#ifdef ASSERT
260void ParMarkBitMap::verify_clear() const
261{
262  const idx_t* const beg = (const idx_t*)_virtual_space->committed_low_addr();
263  const idx_t* const end = (const idx_t*)_virtual_space->committed_high_addr();
264  for (const idx_t* p = beg; p < end; ++p) {
265    assert(*p == 0, "bitmap not clear");
266  }
267}
268#endif  // #ifdef ASSERT
269