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