1 /*
   2  * Copyright (c) 2013, 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_implementation/g1/g1CardCounts.hpp"
  27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  29 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  30 #include "memory/cardTableModRefBS.hpp"
  31 #include "services/memTracker.hpp"
  32 #include "utilities/copy.hpp"
  33 
  34 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
  35   if (has_count_table()) {
  36     assert(from_card_num >= 0 && from_card_num < _committed_max_card_num,
  37            err_msg("from card num out of range: "SIZE_FORMAT, from_card_num));
  38     assert(from_card_num < to_card_num,
  39            err_msg("Wrong order? from: " SIZE_FORMAT ", to: "SIZE_FORMAT,
  40                    from_card_num, to_card_num));
  41     assert(to_card_num <= _committed_max_card_num,
  42            err_msg("to card num out of range: "
  43                    "to: "SIZE_FORMAT ", "
  44                    "max: "SIZE_FORMAT,
  45                    to_card_num, _committed_max_card_num));
  46 
  47     to_card_num = MIN2(_committed_max_card_num, to_card_num);
  48 
  49     Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
  50   }
  51 }
  52 
  53 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
  54   _g1h(g1h), _card_counts(NULL),
  55   _reserved_max_card_num(0), _committed_max_card_num(0),
  56   _committed_size(0) {}
  57 
  58 void G1CardCounts::initialize() {
  59   assert(_g1h->max_capacity() > 0, "initialization order");
  60   assert(_g1h->capacity() == 0, "initialization order");
  61 
  62   if (G1ConcRSHotCardLimit > 0) {
  63     // The max value we can store in the counts table is
  64     // max_jubyte. Guarantee the value of the hot
  65     // threshold limit is no more than this.
  66     guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");
  67 
  68     ModRefBarrierSet* bs = _g1h->mr_bs();
  69     guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
  70     _ct_bs = (CardTableModRefBS*)bs;
  71     _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
  72 
  73     // Allocate/Reserve the counts table
  74     size_t reserved_bytes = _g1h->max_capacity();
  75     _reserved_max_card_num = reserved_bytes >> CardTableModRefBS::card_shift;
  76 
  77     size_t reserved_size = _reserved_max_card_num * sizeof(jbyte);
  78     ReservedSpace rs(ReservedSpace::allocation_align_size_up(reserved_size));
  79     if (!rs.is_reserved()) {
  80       warning("Could not reserve enough space for the card counts table");
  81       guarantee(!has_reserved_count_table(), "should be NULL");
  82       return;
  83     }
  84 
  85     MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
  86 
  87     _card_counts_storage.initialize(rs, 0);
  88     _card_counts = (jubyte*) _card_counts_storage.low();
  89   }
  90 }
  91 
  92 void G1CardCounts::resize(size_t heap_capacity) {
  93   // Expand the card counts table to handle a heap with the given capacity.
  94 
  95   if (!has_reserved_count_table()) {
  96     // Don't expand if we failed to reserve the card counts table.
  97     return;
  98   }
  99 
 100   assert(_committed_size ==
 101          ReservedSpace::allocation_align_size_up(_committed_size),
 102          err_msg("Unaligned? committed_size: " SIZE_FORMAT, _committed_size));
 103 
 104   // Verify that the committed space for the card counts matches our
 105   // committed max card num. Note for some allocation alignments, the
 106   // amount of space actually committed for the counts table will be able
 107   // to span more cards than the number spanned by the maximum heap.
 108   size_t prev_committed_size = _committed_size;
 109   size_t prev_committed_card_num = committed_to_card_num(prev_committed_size);
 110 
 111   assert(prev_committed_card_num == _committed_max_card_num,
 112          err_msg("Card mismatch: "
 113                  "prev: " SIZE_FORMAT ", "
 114                  "committed: "SIZE_FORMAT", "
 115                  "reserved: "SIZE_FORMAT,
 116                  prev_committed_card_num, _committed_max_card_num, _reserved_max_card_num));
 117 
 118   size_t new_size = (heap_capacity >> CardTableModRefBS::card_shift) * sizeof(jbyte);
 119   size_t new_committed_size = ReservedSpace::allocation_align_size_up(new_size);
 120   size_t new_committed_card_num = committed_to_card_num(new_committed_size);
 121 
 122   if (_committed_max_card_num < new_committed_card_num) {
 123     // we need to expand the backing store for the card counts
 124     size_t expand_size = new_committed_size - prev_committed_size;
 125 
 126     if (!_card_counts_storage.expand_by(expand_size)) {
 127       warning("Card counts table backing store commit failure");
 128       return;
 129     }
 130     assert(_card_counts_storage.committed_size() == new_committed_size,
 131            "expansion commit failure");
 132 
 133     _committed_size = new_committed_size;
 134     _committed_max_card_num = new_committed_card_num;
 135 
 136     clear_range(prev_committed_card_num, _committed_max_card_num);
 137   }
 138 }
 139 
 140 uint G1CardCounts::add_card_count(jbyte* card_ptr) {
 141   // Returns the number of times the card has been refined.
 142   // If we failed to reserve/commit the counts table, return 0.
 143   // If card_ptr is beyond the committed end of the counts table,
 144   // return 0.
 145   // Otherwise return the actual count.
 146   // Unless G1ConcRSHotCardLimit has been set appropriately,
 147   // returning 0 will result in the card being considered
 148   // cold and will be refined immediately.
 149   uint count = 0;
 150   if (has_count_table()) {
 151     size_t card_num = ptr_2_card_num(card_ptr);
 152     if (card_num < _committed_max_card_num) {
 153       count = (uint) _card_counts[card_num];
 154       if (count < G1ConcRSHotCardLimit) {
 155         _card_counts[card_num] =
 156           (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
 157       }
 158     }
 159   }
 160   return count;
 161 }
 162 
 163 bool G1CardCounts::is_hot(uint count) {
 164   return (count >= G1ConcRSHotCardLimit);
 165 }
 166 
 167 void G1CardCounts::clear_region(HeapRegion* hr) {
 168   assert(!hr->isHumongous(), "Should have been cleared");
 169   if (has_count_table()) {
 170     HeapWord* bottom = hr->bottom();
 171 
 172     // We use the last address in hr as hr could be the
 173     // last region in the heap. In which case trying to find
 174     // the card for hr->end() will be an OOB accesss to the
 175     // card table.
 176     HeapWord* last = hr->end() - 1;
 177     assert(_g1h->g1_committed().contains(last),
 178            err_msg("last not in committed: "
 179                    "last: " PTR_FORMAT ", "
 180                    "committed: [" PTR_FORMAT ", " PTR_FORMAT ")",
 181                    last,
 182                    _g1h->g1_committed().start(),
 183                    _g1h->g1_committed().end()));
 184 
 185     const jbyte* from_card_ptr = _ct_bs->byte_for_const(bottom);
 186     const jbyte* last_card_ptr = _ct_bs->byte_for_const(last);
 187 
 188 #ifdef ASSERT
 189     HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr);
 190     assert(start_addr == hr->bottom(), "alignment");
 191     HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr);
 192     assert((last_addr + CardTableModRefBS::card_size_in_words) == hr->end(), "alignment");
 193 #endif // ASSERT
 194 
 195     // Clear the counts for the (exclusive) card range.
 196     size_t from_card_num = ptr_2_card_num(from_card_ptr);
 197     size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;
 198     clear_range(from_card_num, to_card_num);
 199   }
 200 }
 201 
 202 void G1CardCounts::clear_all() {
 203   assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
 204   clear_range((size_t)0, _committed_max_card_num);
 205 }
 206 
 207 G1CardCounts::~G1CardCounts() {
 208   if (has_reserved_count_table()) {
 209     _card_counts_storage.release();
 210   }
 211 }
 212