jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 7256: 0fcaab91d485
child 7535: 7ae4e26cb1e0
child 9327: f96fcd9e1e1b
permissions: -rw-r--r--

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

 /*
  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "memory/space.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/java.hpp"
 #include "services/memTracker.hpp"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 //////////////////////////////////////////////////////////////////////
 // G1BlockOffsetSharedArray
 //////////////////////////////////////////////////////////////////////
 G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage) :
   _reserved(), _end(NULL), _listener(), _offset_array(NULL) {
   _reserved = heap;
   _end = NULL;
   MemRegion bot_reserved = storage->reserved();
   _offset_array = (u_char*)bot_reserved.start();
   _end = _reserved.end();
   storage->set_mapping_changed_listener(&_listener);
   if (TraceBlockOffsetTable) {
     gclog_or_tty->print_cr("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: ");
     gclog_or_tty->print_cr("  "
                   "  rs.base(): " INTPTR_FORMAT
                   "  rs.size(): " INTPTR_FORMAT
                   "  rs end(): " INTPTR_FORMAT,
                   bot_reserved.start(), bot_reserved.byte_size(), bot_reserved.end());
   }
 }
 bool G1BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const {
   assert(p >= _reserved.start(), "just checking");
   size_t delta = pointer_delta(p, _reserved.start());
   return (delta & right_n_bits(LogN_words)) == (size_t)NoBits;
 }
 //////////////////////////////////////////////////////////////////////
 // G1BlockOffsetArray
 //////////////////////////////////////////////////////////////////////
 G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array,
                                        MemRegion mr) :
   G1BlockOffsetTable(mr.start(), mr.end()),
   _unallocated_block(_bottom),
   _array(array), _gsp(NULL) {
   assert(_bottom <= _end, "arguments out of order");
 }
 void G1BlockOffsetArray::set_space(G1OffsetTableContigSpace* sp) {
   _gsp = sp;
 }
 // The arguments follow the normal convention of denoting
 // a right-open interval: [start, end)
 void
 G1BlockOffsetArray:: set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) {
   if (start >= end) {
     // The start address is equal to the end address (or to
     // the right of the end address) so there are not cards
     // that need to be updated..
     return;
   }
   // Write the backskip value for each region.
   //
   //    offset
   //    card             2nd                       3rd
   //     | +- 1st        |                         |
   //     v v             v                         v
   //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+     +-+-+-+-+-+-+-+-+-+-+-
   //    |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ...
   //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+     +-+-+-+-+-+-+-+-+-+-+-
   //    11              19                        75
   //      12
   //
   //    offset card is the card that points to the start of an object
   //      x - offset value of offset card
   //    1st - start of first logarithmic region
   //      0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1
   //    2nd - start of second logarithmic region
   //      1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8
   //    3rd - start of third logarithmic region
   //      2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64
   //
   //    integer below the block offset entry is an example of
   //    the index of the entry
   //
   //    Given an address,
   //      Find the index for the address
   //      Find the block offset table entry
   //      Convert the entry to a back slide
   //        (e.g., with today's, offset = 0x81 =>
   //          back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8
   //      Move back N (e.g., 8) entries and repeat with the
   //        value of the new entry
   //
   size_t start_card = _array->index_for(start);
   size_t end_card = _array->index_for(end-1);
   assert(start ==_array->address_for_index(start_card), "Precondition");
   assert(end ==_array->address_for_index(end_card)+N_words, "Precondition");
   set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval
 }
 // Unlike the normal convention in this code, the argument here denotes
 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start()
 // above.
 void
 G1BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) {
   if (start_card > end_card) {
     return;
   }
   assert(start_card > _array->index_for(_bottom), "Cannot be first card");
   assert(_array->offset_array(start_card-1) <= N_words,
          "Offset card has an unexpected value");
   size_t start_card_for_region = start_card;
   u_char offset = max_jubyte;
   for (int i = 0; i < BlockOffsetArray::N_powers; i++) {
     // -1 so that the the card with the actual offset is counted.  Another -1
     // so that the reach ends in this region and not at the start
     // of the next.
     size_t reach = start_card - 1 + (BlockOffsetArray::power_to_cards_back(i+1) - 1);
     offset = N_words + i;
     if (reach >= end_card) {
       _array->set_offset_array(start_card_for_region, end_card, offset);
       start_card_for_region = reach + 1;
       break;
     }
     _array->set_offset_array(start_card_for_region, reach, offset);
     start_card_for_region = reach + 1;
   }
   assert(start_card_for_region > end_card, "Sanity check");
   DEBUG_ONLY(check_all_cards(start_card, end_card);)
 }
 // The card-interval [start_card, end_card] is a closed interval; this
 // is an expensive check -- use with care and only under protection of
 // suitable flag.
 void G1BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const {
   if (end_card < start_card) {
     return;
   }
   guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card");
   for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) {
     u_char entry = _array->offset_array(c);
     if (c - start_card > BlockOffsetArray::power_to_cards_back(1)) {
       guarantee(entry > N_words,
                 err_msg("Should be in logarithmic region - "
                         "entry: " UINT32_FORMAT ", "
                         "_array->offset_array(c): " UINT32_FORMAT ", "
                         "N_words: " UINT32_FORMAT,
                         entry, _array->offset_array(c), N_words));
     }
     size_t backskip = BlockOffsetArray::entry_to_cards_back(entry);
     size_t landing_card = c - backskip;
     guarantee(landing_card >= (start_card - 1), "Inv");
     if (landing_card >= start_card) {
       guarantee(_array->offset_array(landing_card) <= entry,
                 err_msg("Monotonicity - landing_card offset: " UINT32_FORMAT ", "
                         "entry: " UINT32_FORMAT,
                         _array->offset_array(landing_card), entry));
     } else {
       guarantee(landing_card == start_card - 1, "Tautology");
       // Note that N_words is the maximum offset value
       guarantee(_array->offset_array(landing_card) <= N_words,
                 err_msg("landing card offset: " UINT32_FORMAT ", "
                         "N_words: " UINT32_FORMAT,
                         _array->offset_array(landing_card), N_words));
     }
   }
 }
 HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) {
   assert(_bottom <= addr && addr < _end,
          "addr must be covered by this Array");
   // Must read this exactly once because it can be modified by parallel
   // allocation.
   HeapWord* ub = _unallocated_block;
   if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
     assert(ub < _end, "tautology (see above)");
     return ub;
   }
   // Otherwise, find the block start using the table.
   HeapWord* q = block_at_or_preceding(addr, false, 0);
   return forward_to_block_containing_addr(q, addr);
 }
 // This duplicates a little code from the above: unavoidable.
 HeapWord*
 G1BlockOffsetArray::block_start_unsafe_const(const void* addr) const {
   assert(_bottom <= addr && addr < _end,
          "addr must be covered by this Array");
   // Must read this exactly once because it can be modified by parallel
   // allocation.
   HeapWord* ub = _unallocated_block;
   if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
     assert(ub < _end, "tautology (see above)");
     return ub;
   }
   // Otherwise, find the block start using the table.
   HeapWord* q = block_at_or_preceding(addr, false, 0);
   HeapWord* n = q + block_size(q);
   return forward_to_block_containing_addr_const(q, n, addr);
 }
 HeapWord*
 G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord* q,
                                                           HeapWord* n,
                                                           const void* addr) {
   // We're not in the normal case.  We need to handle an important subcase
   // here: LAB allocation.  An allocation previously recorded in the
   // offset table was actually a lab allocation, and was divided into
   // several objects subsequently.  Fix this situation as we answer the
   // query, by updating entries as we cross them.
   // If the fist object's end q is at the card boundary. Start refining
   // with the corresponding card (the value of the entry will be basically
   // set to 0). If the object crosses the boundary -- start from the next card.
   size_t n_index = _array->index_for(n);
   size_t next_index = _array->index_for(n) + !_array->is_card_boundary(n);
   // Calculate a consistent next boundary.  If "n" is not at the boundary
   // already, step to the boundary.
   HeapWord* next_boundary = _array->address_for_index(n_index) +
                             (n_index == next_index ? 0 : N_words);
   assert(next_boundary <= _array->_end,
          err_msg("next_boundary is beyond the end of the covered region "
                  " next_boundary " PTR_FORMAT " _array->_end " PTR_FORMAT,
                  next_boundary, _array->_end));
   if (addr >= gsp()->top()) return gsp()->top();
   while (next_boundary < addr) {
     while (n <= next_boundary) {
       q = n;
       oop obj = oop(q);
       if (obj->klass_or_null() == NULL) return q;
       n += block_size(q);
     }
     assert(q <= next_boundary && n > next_boundary, "Consequence of loop");
     // [q, n) is the block that crosses the boundary.
     alloc_block_work2(&next_boundary, &next_index, q, n);
   }
   return forward_to_block_containing_addr_const(q, n, addr);
 }
 // Note that the committed size of the covered space may have changed,
 // so the table size might also wish to change.
 void G1BlockOffsetArray::resize(size_t new_word_size) {
   HeapWord* new_end = _bottom + new_word_size;
   _end = new_end;  // update _end
 }
 //
 //              threshold_
 //              |   _index_
 //              v   v
 //      +-------+-------+-------+-------+-------+
 //      | i-1   |   i   | i+1   | i+2   | i+3   |
 //      +-------+-------+-------+-------+-------+
 //       ( ^    ]
 //         block-start
 //
 void G1BlockOffsetArray::alloc_block_work2(HeapWord** threshold_, size_t* index_,
                                            HeapWord* blk_start, HeapWord* blk_end) {
   // For efficiency, do copy-in/copy-out.
   HeapWord* threshold = *threshold_;
   size_t    index = *index_;
   assert(blk_start != NULL && blk_end > blk_start,
          "phantom block");
   assert(blk_end > threshold, "should be past threshold");
   assert(blk_start <= threshold, "blk_start should be at or before threshold");
   assert(pointer_delta(threshold, blk_start) <= N_words,
          "offset should be <= BlockOffsetSharedArray::N");
   assert(Universe::heap()->is_in_reserved(blk_start),
          "reference must be into the heap");
   assert(Universe::heap()->is_in_reserved(blk_end-1),
          "limit must be within the heap");
   assert(threshold == _array->_reserved.start() + index*N_words,
          "index must agree with threshold");
   DEBUG_ONLY(size_t orig_index = index;)
   // Mark the card that holds the offset into the block.  Note
   // that _next_offset_index and _next_offset_threshold are not
   // updated until the end of this method.
   _array->set_offset_array(index, threshold, blk_start);
   // We need to now mark the subsequent cards that this blk spans.
   // Index of card on which blk ends.
   size_t end_index   = _array->index_for(blk_end - 1);
   // Are there more cards left to be updated?
   if (index + 1 <= end_index) {
     HeapWord* rem_st  = _array->address_for_index(index + 1);
     // Calculate rem_end this way because end_index
     // may be the last valid index in the covered region.
     HeapWord* rem_end = _array->address_for_index(end_index) +  N_words;
     set_remainder_to_point_to_start(rem_st, rem_end);
   }
   index = end_index + 1;
   // Calculate threshold_ this way because end_index
   // may be the last valid index in the covered region.
   threshold = _array->address_for_index(end_index) + N_words;
   assert(threshold >= blk_end, "Incorrect offset threshold");
   // index_ and threshold_ updated here.
   *threshold_ = threshold;
   *index_ = index;
 #ifdef ASSERT
   // The offset can be 0 if the block starts on a boundary.  That
   // is checked by an assertion above.
   size_t start_index = _array->index_for(blk_start);
   HeapWord* boundary = _array->address_for_index(start_index);
   assert((_array->offset_array(orig_index) == 0 &&
           blk_start == boundary) ||
           (_array->offset_array(orig_index) > 0 &&
          _array->offset_array(orig_index) <= N_words),
          err_msg("offset array should have been set - "
                   "orig_index offset: " UINT32_FORMAT ", "
                   "blk_start: " PTR_FORMAT ", "
                   "boundary: " PTR_FORMAT,
                   _array->offset_array(orig_index),
                   blk_start, boundary));
   for (size_t j = orig_index + 1; j <= end_index; j++) {
     assert(_array->offset_array(j) > 0 &&
            _array->offset_array(j) <=
              (u_char) (N_words+BlockOffsetArray::N_powers-1),
            err_msg("offset array should have been set - "
                    UINT32_FORMAT " not > 0 OR "
                    UINT32_FORMAT " not <= " UINT32_FORMAT,
                    _array->offset_array(j),
                    _array->offset_array(j),
                    (u_char) (N_words+BlockOffsetArray::N_powers-1)));
   }
 #endif
 }
 bool
 G1BlockOffsetArray::verify_for_object(HeapWord* obj_start,
                                       size_t word_size) const {
   size_t first_card = _array->index_for(obj_start);
   size_t last_card = _array->index_for(obj_start + word_size - 1);
   if (!_array->is_card_boundary(obj_start)) {
     // If the object is not on a card boundary the BOT entry of the
     // first card should point to another object so we should not
     // check that one.
     first_card += 1;
   }
   for (size_t card = first_card; card <= last_card; card += 1) {
     HeapWord* card_addr = _array->address_for_index(card);
     HeapWord* block_start = block_start_const(card_addr);
     if (block_start != obj_start) {
       gclog_or_tty->print_cr("block start: "PTR_FORMAT" is incorrect - "
                              "card index: "SIZE_FORMAT" "
                              "card addr: "PTR_FORMAT" BOT entry: %u "
                              "obj: "PTR_FORMAT" word size: "SIZE_FORMAT" "
                              "cards: ["SIZE_FORMAT","SIZE_FORMAT"]",
                              block_start, card, card_addr,
                              _array->offset_array(card),
                              obj_start, word_size, first_card, last_card);
       return false;
     }
   }
   return true;
 }
 #ifndef PRODUCT
 void
 G1BlockOffsetArray::print_on(outputStream* out) {
   size_t from_index = _array->index_for(_bottom);
   size_t to_index = _array->index_for(_end);
   out->print_cr(">> BOT for area ["PTR_FORMAT","PTR_FORMAT") "
                 "cards ["SIZE_FORMAT","SIZE_FORMAT")",
                 _bottom, _end, from_index, to_index);
   for (size_t i = from_index; i < to_index; ++i) {
     out->print_cr("  entry "SIZE_FORMAT_W(8)" | "PTR_FORMAT" : %3u",
                   i, _array->address_for_index(i),
                   (uint) _array->offset_array(i));
   }
 }
 #endif // !PRODUCT
 //////////////////////////////////////////////////////////////////////
 // G1BlockOffsetArrayContigSpace
 //////////////////////////////////////////////////////////////////////
 HeapWord*
 G1BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) {
   assert(_bottom <= addr && addr < _end,
          "addr must be covered by this Array");
   HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
   return forward_to_block_containing_addr(q, addr);
 }
 HeapWord*
 G1BlockOffsetArrayContigSpace::
 block_start_unsafe_const(const void* addr) const {
   assert(_bottom <= addr && addr < _end,
          "addr must be covered by this Array");
   HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
   HeapWord* n = q + block_size(q);
   return forward_to_block_containing_addr_const(q, n, addr);
 }
 G1BlockOffsetArrayContigSpace::
 G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array,
                               MemRegion mr) :
   G1BlockOffsetArray(array, mr)
 {
   _next_offset_threshold = NULL;
   _next_offset_index = 0;
 }
 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold_raw() {
   assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
          "just checking");
   _next_offset_index = _array->index_for_raw(_bottom);
   _next_offset_index++;
   _next_offset_threshold =
     _array->address_for_index_raw(_next_offset_index);
   return _next_offset_threshold;
 }
 void G1BlockOffsetArrayContigSpace::zero_bottom_entry_raw() {
   assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
          "just checking");
   size_t bottom_index = _array->index_for_raw(_bottom);
   assert(_array->address_for_index_raw(bottom_index) == _bottom,
          "Precondition of call");
   _array->set_offset_array_raw(bottom_index, 0);
 }
 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() {
   assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
          "just checking");
   _next_offset_index = _array->index_for(_bottom);
   _next_offset_index++;
   _next_offset_threshold =
     _array->address_for_index(_next_offset_index);
   return _next_offset_threshold;
 }
 void
 G1BlockOffsetArrayContigSpace::set_for_starts_humongous(HeapWord* new_top) {
   assert(new_top <= _end, "_end should have already been updated");
   // The first BOT entry should have offset 0.
   reset_bot();
   alloc_block(_bottom, new_top);
  }
 #ifndef PRODUCT
 void
 G1BlockOffsetArrayContigSpace::print_on(outputStream* out) {
   G1BlockOffsetArray::print_on(out);
   out->print_cr("  next offset threshold: "PTR_FORMAT, _next_offset_threshold);
   out->print_cr("  next offset index:     "SIZE_FORMAT, _next_offset_index);
 }
 #endif // !PRODUCT

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp