| /* |
| * Copyright (c) 2001, 2017, 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/g1/g1BlockOffsetTable.inline.hpp" |
| #include "gc/g1/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/heapRegion.hpp" |
| #include "gc/shared/space.hpp" |
| #include "logging/log.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/java.hpp" |
| #include "services/memTracker.hpp" |
| |
| |
| |
| ////////////////////////////////////////////////////////////////////// |
| // G1BlockOffsetTable |
| ////////////////////////////////////////////////////////////////////// |
| |
| G1BlockOffsetTable::G1BlockOffsetTable(MemRegion heap, G1RegionToSpaceMapper* storage) : |
| _reserved(heap), _offset_array(NULL) { |
| |
| MemRegion bot_reserved = storage->reserved(); |
| |
| _offset_array = (u_char*)bot_reserved.start(); |
| |
| log_trace(gc, bot)("G1BlockOffsetTable::G1BlockOffsetTable: "); |
| log_trace(gc, bot)(" rs.base(): " PTR_FORMAT " rs.size(): " SIZE_FORMAT " rs end(): " PTR_FORMAT, |
| p2i(bot_reserved.start()), bot_reserved.byte_size(), p2i(bot_reserved.end())); |
| } |
| |
| bool G1BlockOffsetTable::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((int)BOTConstants::LogN_words)) == (size_t)NoBits; |
| } |
| |
| #ifdef ASSERT |
| void G1BlockOffsetTable::check_index(size_t index, const char* msg) const { |
| assert((index) < (_reserved.word_size() >> BOTConstants::LogN_words), |
| "%s - index: " SIZE_FORMAT ", _vs.committed_size: " SIZE_FORMAT, |
| msg, (index), (_reserved.word_size() >> BOTConstants::LogN_words)); |
| assert(G1CollectedHeap::heap()->is_in_exact(address_for_index_raw(index)), |
| "Index " SIZE_FORMAT " corresponding to " PTR_FORMAT |
| " (%u) is not in committed area.", |
| (index), |
| p2i(address_for_index_raw(index)), |
| G1CollectedHeap::heap()->addr_to_region(address_for_index_raw(index))); |
| } |
| #endif // ASSERT |
| |
| ////////////////////////////////////////////////////////////////////// |
| // G1BlockOffsetTablePart |
| ////////////////////////////////////////////////////////////////////// |
| |
| G1BlockOffsetTablePart::G1BlockOffsetTablePart(G1BlockOffsetTable* array, G1ContiguousSpace* gsp) : |
| _bot(array), |
| _space(gsp), |
| _next_offset_threshold(NULL), |
| _next_offset_index(0) |
| { |
| debug_only(_object_can_span = false;) |
| } |
| |
| // The arguments follow the normal convention of denoting |
| // a right-open interval: [start, end) |
| void G1BlockOffsetTablePart:: 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 = _bot->index_for(start); |
| size_t end_card = _bot->index_for(end-1); |
| assert(start ==_bot->address_for_index(start_card), "Precondition"); |
| assert(end ==_bot->address_for_index(end_card)+BOTConstants::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 G1BlockOffsetTablePart::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) { |
| if (start_card > end_card) { |
| return; |
| } |
| assert(start_card > _bot->index_for(_space->bottom()), "Cannot be first card"); |
| assert(_bot->offset_array(start_card-1) <= BOTConstants::N_words, |
| "Offset card has an unexpected value"); |
| size_t start_card_for_region = start_card; |
| u_char offset = max_jubyte; |
| for (uint i = 0; i < BOTConstants::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 + (BOTConstants::power_to_cards_back(i+1) - 1); |
| offset = BOTConstants::N_words + i; |
| if (reach >= end_card) { |
| _bot->set_offset_array(start_card_for_region, end_card, offset); |
| start_card_for_region = reach + 1; |
| break; |
| } |
| _bot->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 G1BlockOffsetTablePart::check_all_cards(size_t start_card, size_t end_card) const { |
| |
| if (end_card < start_card) { |
| return; |
| } |
| guarantee(_bot->offset_array(start_card) == BOTConstants::N_words, "Wrong value in second card"); |
| for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) { |
| u_char entry = _bot->offset_array(c); |
| if (c - start_card > BOTConstants::power_to_cards_back(1)) { |
| guarantee(entry > BOTConstants::N_words, |
| "Should be in logarithmic region - " |
| "entry: %u, " |
| "_array->offset_array(c): %u, " |
| "N_words: %u", |
| (uint)entry, (uint)_bot->offset_array(c), BOTConstants::N_words); |
| } |
| size_t backskip = BOTConstants::entry_to_cards_back(entry); |
| size_t landing_card = c - backskip; |
| guarantee(landing_card >= (start_card - 1), "Inv"); |
| if (landing_card >= start_card) { |
| guarantee(_bot->offset_array(landing_card) <= entry, |
| "Monotonicity - landing_card offset: %u, " |
| "entry: %u", |
| (uint)_bot->offset_array(landing_card), (uint)entry); |
| } else { |
| guarantee(landing_card == start_card - 1, "Tautology"); |
| // Note that N_words is the maximum offset value |
| guarantee(_bot->offset_array(landing_card) <= BOTConstants::N_words, |
| "landing card offset: %u, " |
| "N_words: %u", |
| (uint)_bot->offset_array(landing_card), (uint)BOTConstants::N_words); |
| } |
| } |
| } |
| |
| HeapWord* G1BlockOffsetTablePart::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 = _bot->index_for(n); |
| size_t next_index = _bot->index_for(n) + !_bot->is_card_boundary(n); |
| // Calculate a consistent next boundary. If "n" is not at the boundary |
| // already, step to the boundary. |
| HeapWord* next_boundary = _bot->address_for_index(n_index) + |
| (n_index == next_index ? 0 : BOTConstants::N_words); |
| assert(next_boundary <= _bot->_reserved.end(), |
| "next_boundary is beyond the end of the covered region " |
| " next_boundary " PTR_FORMAT " _array->_end " PTR_FORMAT, |
| p2i(next_boundary), p2i(_bot->_reserved.end())); |
| if (addr >= _space->top()) return _space->top(); |
| while (next_boundary < addr) { |
| while (n <= next_boundary) { |
| q = n; |
| oop obj = oop(q); |
| if (obj->klass_or_null_acquire() == 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_work(&next_boundary, &next_index, q, n); |
| } |
| return forward_to_block_containing_addr_const(q, n, addr); |
| } |
| |
| // |
| // threshold_ |
| // | _index_ |
| // v v |
| // +-------+-------+-------+-------+-------+ |
| // | i-1 | i | i+1 | i+2 | i+3 | |
| // +-------+-------+-------+-------+-------+ |
| // ( ^ ] |
| // block-start |
| // |
| void G1BlockOffsetTablePart::alloc_block_work(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) <= BOTConstants::N_words, |
| "offset should be <= BlockOffsetSharedArray::N"); |
| assert(G1CollectedHeap::heap()->is_in_reserved(blk_start), |
| "reference must be into the heap"); |
| assert(G1CollectedHeap::heap()->is_in_reserved(blk_end-1), |
| "limit must be within the heap"); |
| assert(threshold == _bot->_reserved.start() + index*BOTConstants::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. |
| _bot->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 = _bot->index_for(blk_end - 1); |
| |
| // Are there more cards left to be updated? |
| if (index + 1 <= end_index) { |
| HeapWord* rem_st = _bot->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 = _bot->address_for_index(end_index) + BOTConstants::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 = _bot->address_for_index(end_index) + BOTConstants::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 = _bot->index_for(blk_start); |
| HeapWord* boundary = _bot->address_for_index(start_index); |
| assert((_bot->offset_array(orig_index) == 0 && blk_start == boundary) || |
| (_bot->offset_array(orig_index) > 0 && _bot->offset_array(orig_index) <= BOTConstants::N_words), |
| "offset array should have been set - " |
| "orig_index offset: %u, " |
| "blk_start: " PTR_FORMAT ", " |
| "boundary: " PTR_FORMAT, |
| (uint)_bot->offset_array(orig_index), |
| p2i(blk_start), p2i(boundary)); |
| for (size_t j = orig_index + 1; j <= end_index; j++) { |
| assert(_bot->offset_array(j) > 0 && |
| _bot->offset_array(j) <= |
| (u_char) (BOTConstants::N_words+BOTConstants::N_powers-1), |
| "offset array should have been set - " |
| "%u not > 0 OR %u not <= %u", |
| (uint) _bot->offset_array(j), |
| (uint) _bot->offset_array(j), |
| (uint) (BOTConstants::N_words+BOTConstants::N_powers-1)); |
| } |
| #endif |
| } |
| |
| void G1BlockOffsetTablePart::verify() const { |
| assert(_space->bottom() < _space->top(), "Only non-empty regions should be verified."); |
| size_t start_card = _bot->index_for(_space->bottom()); |
| size_t end_card = _bot->index_for(_space->top() - 1); |
| |
| for (size_t current_card = start_card; current_card < end_card; current_card++) { |
| u_char entry = _bot->offset_array(current_card); |
| if (entry < BOTConstants::N_words) { |
| // The entry should point to an object before the current card. Verify that |
| // it is possible to walk from that object in to the current card by just |
| // iterating over the objects following it. |
| HeapWord* card_address = _bot->address_for_index(current_card); |
| HeapWord* obj_end = card_address - entry; |
| while (obj_end < card_address) { |
| HeapWord* obj = obj_end; |
| size_t obj_size = block_size(obj); |
| obj_end = obj + obj_size; |
| guarantee(obj_end > obj && obj_end <= _space->top(), |
| "Invalid object end. obj: " PTR_FORMAT " obj_size: " SIZE_FORMAT " obj_end: " PTR_FORMAT " top: " PTR_FORMAT, |
| p2i(obj), obj_size, p2i(obj_end), p2i(_space->top())); |
| } |
| } else { |
| // Because we refine the BOT based on which cards are dirty there is not much we can verify here. |
| // We need to make sure that we are going backwards and that we don't pass the start of the |
| // corresponding heap region. But that is about all we can verify. |
| size_t backskip = BOTConstants::entry_to_cards_back(entry); |
| guarantee(backskip >= 1, "Must be going back at least one card."); |
| |
| size_t max_backskip = current_card - start_card; |
| guarantee(backskip <= max_backskip, |
| "Going backwards beyond the start_card. start_card: " SIZE_FORMAT " current_card: " SIZE_FORMAT " backskip: " SIZE_FORMAT, |
| start_card, current_card, backskip); |
| |
| HeapWord* backskip_address = _bot->address_for_index(current_card - backskip); |
| guarantee(backskip_address >= _space->bottom(), |
| "Going backwards beyond bottom of the region: bottom: " PTR_FORMAT ", backskip_address: " PTR_FORMAT, |
| p2i(_space->bottom()), p2i(backskip_address)); |
| } |
| } |
| } |
| |
| #ifdef ASSERT |
| void G1BlockOffsetTablePart::set_object_can_span(bool can_span) { |
| _object_can_span = can_span; |
| } |
| #endif |
| |
| #ifndef PRODUCT |
| void |
| G1BlockOffsetTablePart::print_on(outputStream* out) { |
| size_t from_index = _bot->index_for(_space->bottom()); |
| size_t to_index = _bot->index_for(_space->end()); |
| out->print_cr(">> BOT for area [" PTR_FORMAT "," PTR_FORMAT ") " |
| "cards [" SIZE_FORMAT "," SIZE_FORMAT ")", |
| p2i(_space->bottom()), p2i(_space->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, p2i(_bot->address_for_index(i)), |
| (uint) _bot->offset_array(i)); |
| } |
| out->print_cr(" next offset threshold: " PTR_FORMAT, p2i(_next_offset_threshold)); |
| out->print_cr(" next offset index: " SIZE_FORMAT, _next_offset_index); |
| } |
| #endif // !PRODUCT |
| |
| HeapWord* G1BlockOffsetTablePart::initialize_threshold_raw() { |
| _next_offset_index = _bot->index_for_raw(_space->bottom()); |
| _next_offset_index++; |
| _next_offset_threshold = |
| _bot->address_for_index_raw(_next_offset_index); |
| return _next_offset_threshold; |
| } |
| |
| void G1BlockOffsetTablePart::zero_bottom_entry_raw() { |
| size_t bottom_index = _bot->index_for_raw(_space->bottom()); |
| assert(_bot->address_for_index_raw(bottom_index) == _space->bottom(), |
| "Precondition of call"); |
| _bot->set_offset_array_raw(bottom_index, 0); |
| } |
| |
| HeapWord* G1BlockOffsetTablePart::initialize_threshold() { |
| _next_offset_index = _bot->index_for(_space->bottom()); |
| _next_offset_index++; |
| _next_offset_threshold = |
| _bot->address_for_index(_next_offset_index); |
| return _next_offset_threshold; |
| } |
| |
| void G1BlockOffsetTablePart::set_for_starts_humongous(HeapWord* obj_top, size_t fill_size) { |
| // The first BOT entry should have offset 0. |
| reset_bot(); |
| alloc_block(_space->bottom(), obj_top); |
| if (fill_size > 0) { |
| alloc_block(obj_top, fill_size); |
| } |
| } |
