/* * Copyright 2000-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ // This kind of "BarrierSet" allows a "CollectedHeap" to detect and // enumerate ref fields that have been modified (since the last // enumeration.) # include "incls/_precompiled.incl" # include "incls/_cardTableModRefBS.cpp.incl" size_t CardTableModRefBS::cards_required(size_t covered_words) { // Add one for a guard card, used to detect errors. const size_t words = align_size_up(covered_words, card_size_in_words); return words / card_size_in_words + 1; } size_t CardTableModRefBS::compute_byte_map_size() { assert(_guard_index == cards_required(_whole_heap.word_size()) - 1, "unitialized, check declaration order"); assert(_page_size != 0, "unitialized, check declaration order"); const size_t granularity = os::vm_allocation_granularity(); return align_size_up(_guard_index + 1, MAX2(_page_size, granularity)); } CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap, int max_covered_regions): ModRefBarrierSet(max_covered_regions), _whole_heap(whole_heap), _guard_index(cards_required(whole_heap.word_size()) - 1), _last_valid_index(_guard_index - 1), _page_size(os::vm_page_size()), _byte_map_size(compute_byte_map_size()) { _kind = BarrierSet::CardTableModRef; HeapWord* low_bound = _whole_heap.start(); HeapWord* high_bound = _whole_heap.end(); assert((uintptr_t(low_bound) & (card_size - 1)) == 0, "heap must start at card boundary"); assert((uintptr_t(high_bound) & (card_size - 1)) == 0, "heap must end at card boundary"); assert(card_size <= 512, "card_size must be less than 512"); // why? _covered = new MemRegion[max_covered_regions]; _committed = new MemRegion[max_covered_regions]; if (_covered == NULL || _committed == NULL) vm_exit_during_initialization("couldn't alloc card table covered region set."); int i; for (i = 0; i < max_covered_regions; i++) { _covered[i].set_word_size(0); _committed[i].set_word_size(0); } _cur_covered_regions = 0; const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 : MAX2(_page_size, (size_t) os::vm_allocation_granularity()); ReservedSpace heap_rs(_byte_map_size, rs_align, false); os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1, _page_size, heap_rs.base(), heap_rs.size()); if (!heap_rs.is_reserved()) { vm_exit_during_initialization("Could not reserve enough space for the " "card marking array"); } // The assember store_check code will do an unsigned shift of the oop, // then add it to byte_map_base, i.e. // // _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift) _byte_map = (jbyte*) heap_rs.base(); byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift); assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map"); assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map"); jbyte* guard_card = &_byte_map[_guard_index]; uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size); _guard_region = MemRegion((HeapWord*)guard_page, _page_size); if (!os::commit_memory((char*)guard_page, _page_size, _page_size)) { // Do better than this for Merlin vm_exit_out_of_memory(_page_size, "card table last card"); } *guard_card = last_card; _lowest_non_clean = NEW_C_HEAP_ARRAY(CardArr, max_covered_regions); _lowest_non_clean_chunk_size = NEW_C_HEAP_ARRAY(size_t, max_covered_regions); _lowest_non_clean_base_chunk_index = NEW_C_HEAP_ARRAY(uintptr_t, max_covered_regions); _last_LNC_resizing_collection = NEW_C_HEAP_ARRAY(int, max_covered_regions); if (_lowest_non_clean == NULL || _lowest_non_clean_chunk_size == NULL || _lowest_non_clean_base_chunk_index == NULL || _last_LNC_resizing_collection == NULL) vm_exit_during_initialization("couldn't allocate an LNC array."); for (i = 0; i < max_covered_regions; i++) { _lowest_non_clean[i] = NULL; _lowest_non_clean_chunk_size[i] = 0; _last_LNC_resizing_collection[i] = -1; } if (TraceCardTableModRefBS) { gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: "); gclog_or_tty->print_cr(" " " &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT, &_byte_map[0], &_byte_map[_last_valid_index]); gclog_or_tty->print_cr(" " " byte_map_base: " INTPTR_FORMAT, byte_map_base); } } int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) { int i; for (i = 0; i < _cur_covered_regions; i++) { if (_covered[i].start() == base) return i; if (_covered[i].start() > base) break; } // If we didn't find it, create a new one. assert(_cur_covered_regions < _max_covered_regions, "too many covered regions"); // Move the ones above up, to maintain sorted order. for (int j = _cur_covered_regions; j > i; j--) { _covered[j] = _covered[j-1]; _committed[j] = _committed[j-1]; } int res = i; _cur_covered_regions++; _covered[res].set_start(base); _covered[res].set_word_size(0); jbyte* ct_start = byte_for(base); uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size); _committed[res].set_start((HeapWord*)ct_start_aligned); _committed[res].set_word_size(0); return res; } int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) { for (int i = 0; i < _cur_covered_regions; i++) { if (_covered[i].contains(addr)) { return i; } } assert(0, "address outside of heap?"); return -1; } HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const { HeapWord* max_end = NULL; for (int j = 0; j < ind; j++) { HeapWord* this_end = _committed[j].end(); if (this_end > max_end) max_end = this_end; } return max_end; } MemRegion CardTableModRefBS::committed_unique_to_self(int self, MemRegion mr) const { MemRegion result = mr; for (int r = 0; r < _cur_covered_regions; r += 1) { if (r != self) { result = result.minus(_committed[r]); } } // Never include the guard page. result = result.minus(_guard_region); return result; } void CardTableModRefBS::resize_covered_region(MemRegion new_region) { // We don't change the start of a region, only the end. assert(_whole_heap.contains(new_region), "attempt to cover area not in reserved area"); debug_only(verify_guard();) // collided is true if the expansion would push into another committed region debug_only(bool collided = false;) int const ind = find_covering_region_by_base(new_region.start()); MemRegion const old_region = _covered[ind]; assert(old_region.start() == new_region.start(), "just checking"); if (new_region.word_size() != old_region.word_size()) { // Commit new or uncommit old pages, if necessary. MemRegion cur_committed = _committed[ind]; // Extend the end of this _commited region // to cover the end of any lower _committed regions. // This forms overlapping regions, but never interior regions. HeapWord* const max_prev_end = largest_prev_committed_end(ind); if (max_prev_end > cur_committed.end()) { cur_committed.set_end(max_prev_end); } // Align the end up to a page size (starts are already aligned). jbyte* const new_end = byte_after(new_region.last()); HeapWord* new_end_aligned = (HeapWord*) align_size_up((uintptr_t)new_end, _page_size); assert(new_end_aligned >= (HeapWord*) new_end, "align up, but less"); int ri = 0; for (ri = 0; ri < _cur_covered_regions; ri++) { if (ri != ind) { if (_committed[ri].contains(new_end_aligned)) { assert((new_end_aligned >= _committed[ri].start()) && (_committed[ri].start() > _committed[ind].start()), "New end of committed region is inconsistent"); new_end_aligned = _committed[ri].start(); assert(new_end_aligned > _committed[ind].start(), "New end of committed region is before start"); debug_only(collided = true;) // Should only collide with 1 region break; } } } #ifdef ASSERT for (++ri; ri < _cur_covered_regions; ri++) { assert(!_committed[ri].contains(new_end_aligned), "New end of committed region is in a second committed region"); } #endif // The guard page is always committed and should not be committed over. HeapWord* const new_end_for_commit = MIN2(new_end_aligned, _guard_region.start()); if (new_end_for_commit > cur_committed.end()) { // Must commit new pages. MemRegion const new_committed = MemRegion(cur_committed.end(), new_end_for_commit); assert(!new_committed.is_empty(), "Region should not be empty here"); if (!os::commit_memory((char*)new_committed.start(), new_committed.byte_size(), _page_size)) { // Do better than this for Merlin vm_exit_out_of_memory(new_committed.byte_size(), "card table expansion"); } // Use new_end_aligned (as opposed to new_end_for_commit) because // the cur_committed region may include the guard region. } else if (new_end_aligned < cur_committed.end()) { // Must uncommit pages. MemRegion const uncommit_region = committed_unique_to_self(ind, MemRegion(new_end_aligned, cur_committed.end())); if (!uncommit_region.is_empty()) { if (!os::uncommit_memory((char*)uncommit_region.start(), uncommit_region.byte_size())) { assert(false, "Card table contraction failed"); // The call failed so don't change the end of the // committed region. This is better than taking the // VM down. new_end_aligned = _committed[ind].end(); } } } // In any case, we can reset the end of the current committed entry. _committed[ind].set_end(new_end_aligned); // The default of 0 is not necessarily clean cards. jbyte* entry; if (old_region.last() < _whole_heap.start()) { entry = byte_for(_whole_heap.start()); } else { entry = byte_after(old_region.last()); } assert(index_for(new_region.last()) < _guard_index, "The guard card will be overwritten"); // This line commented out cleans the newly expanded region and // not the aligned up expanded region. // jbyte* const end = byte_after(new_region.last()); jbyte* const end = (jbyte*) new_end_for_commit; assert((end >= byte_after(new_region.last())) || collided, "Expect to be beyond new region unless impacting another region"); // do nothing if we resized downward. #ifdef ASSERT for (int ri = 0; ri < _cur_covered_regions; ri++) { if (ri != ind) { // The end of the new committed region should not // be in any existing region unless it matches // the start of the next region. assert(!_committed[ri].contains(end) || (_committed[ri].start() == (HeapWord*) end), "Overlapping committed regions"); } } #endif if (entry < end) { memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte))); } } // In any case, the covered size changes. _covered[ind].set_word_size(new_region.word_size()); if (TraceCardTableModRefBS) { gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); gclog_or_tty->print_cr(" " " _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, ind, _covered[ind].start(), ind, _covered[ind].last()); gclog_or_tty->print_cr(" " " _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, ind, _committed[ind].start(), ind, _committed[ind].last()); gclog_or_tty->print_cr(" " " byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, byte_for(_covered[ind].start()), byte_for(_covered[ind].last())); gclog_or_tty->print_cr(" " " addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT, addr_for((jbyte*) _committed[ind].start()), addr_for((jbyte*) _committed[ind].last())); } debug_only(verify_guard();) } // Note that these versions are precise! The scanning code has to handle the // fact that the write barrier may be either precise or imprecise. void CardTableModRefBS::write_ref_field_work(void* field, oop newVal) { inline_write_ref_field(field, newVal); } bool CardTableModRefBS::claim_card(size_t card_index) { jbyte val = _byte_map[card_index]; if (val != claimed_card_val()) { jbyte res = Atomic::cmpxchg((jbyte) claimed_card_val(), &_byte_map[card_index], val); if (res == val) return true; else return false; } return false; } void CardTableModRefBS::non_clean_card_iterate(Space* sp, MemRegion mr, DirtyCardToOopClosure* dcto_cl, MemRegionClosure* cl, bool clear) { if (!mr.is_empty()) { int n_threads = SharedHeap::heap()->n_par_threads(); if (n_threads > 0) { #ifndef SERIALGC par_non_clean_card_iterate_work(sp, mr, dcto_cl, cl, clear, n_threads); #else // SERIALGC fatal("Parallel gc not supported here."); #endif // SERIALGC } else { non_clean_card_iterate_work(mr, cl, clear); } } } // NOTE: For this to work correctly, it is important that // we look for non-clean cards below (so as to catch those // marked precleaned), rather than look explicitly for dirty // cards (and miss those marked precleaned). In that sense, // the name precleaned is currently somewhat of a misnomer. void CardTableModRefBS::non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl, bool clear) { // Figure out whether we have to worry about parallelism. bool is_par = (SharedHeap::heap()->n_par_threads() > 1); for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (mri.word_size() > 0) { jbyte* cur_entry = byte_for(mri.last()); jbyte* limit = byte_for(mri.start()); while (cur_entry >= limit) { jbyte* next_entry = cur_entry - 1; if (*cur_entry != clean_card) { size_t non_clean_cards = 1; // Should the next card be included in this range of dirty cards. while (next_entry >= limit && *next_entry != clean_card) { non_clean_cards++; cur_entry = next_entry; next_entry--; } // The memory region may not be on a card boundary. So that // objects beyond the end of the region are not processed, make // cur_cards precise with regard to the end of the memory region. MemRegion cur_cards(addr_for(cur_entry), non_clean_cards * card_size_in_words); MemRegion dirty_region = cur_cards.intersection(mri); if (clear) { for (size_t i = 0; i < non_clean_cards; i++) { // Clean the dirty cards (but leave the other non-clean // alone.) If parallel, do the cleaning atomically. jbyte cur_entry_val = cur_entry[i]; if (card_is_dirty_wrt_gen_iter(cur_entry_val)) { if (is_par) { jbyte res = Atomic::cmpxchg(clean_card, &cur_entry[i], cur_entry_val); assert(res != clean_card, "Dirty card mysteriously cleaned"); } else { cur_entry[i] = clean_card; } } } } cl->do_MemRegion(dirty_region); } cur_entry = next_entry; } } } } void CardTableModRefBS::mod_oop_in_space_iterate(Space* sp, OopClosure* cl, bool clear, bool before_save_marks) { // Note that dcto_cl is resource-allocated, so there is no // corresponding "delete". DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision()); MemRegion used_mr; if (before_save_marks) { used_mr = sp->used_region_at_save_marks(); } else { used_mr = sp->used_region(); } non_clean_card_iterate(sp, used_mr, dcto_cl, dcto_cl, clear); } void CardTableModRefBS::dirty_MemRegion(MemRegion mr) { jbyte* cur = byte_for(mr.start()); jbyte* last = byte_after(mr.last()); while (cur < last) { *cur = dirty_card; cur++; } } void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (!mri.is_empty()) dirty_MemRegion(mri); } } void CardTableModRefBS::clear_MemRegion(MemRegion mr) { // Be conservative: only clean cards entirely contained within the // region. jbyte* cur; if (mr.start() == _whole_heap.start()) { cur = byte_for(mr.start()); } else { assert(mr.start() > _whole_heap.start(), "mr is not covered."); cur = byte_after(mr.start() - 1); } jbyte* last = byte_after(mr.last()); memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte))); } void CardTableModRefBS::clear(MemRegion mr) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (!mri.is_empty()) clear_MemRegion(mri); } } void CardTableModRefBS::dirty(MemRegion mr) { jbyte* first = byte_for(mr.start()); jbyte* last = byte_after(mr.last()); memset(first, dirty_card, last-first); } // NOTES: // (1) Unlike mod_oop_in_space_iterate() above, dirty_card_iterate() // iterates over dirty cards ranges in increasing address order. void CardTableModRefBS::dirty_card_iterate(MemRegion mr, MemRegionClosure* cl) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (!mri.is_empty()) { jbyte *cur_entry, *next_entry, *limit; for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last()); cur_entry <= limit; cur_entry = next_entry) { next_entry = cur_entry + 1; if (*cur_entry == dirty_card) { size_t dirty_cards; // Accumulate maximal dirty card range, starting at cur_entry for (dirty_cards = 1; next_entry <= limit && *next_entry == dirty_card; dirty_cards++, next_entry++); MemRegion cur_cards(addr_for(cur_entry), dirty_cards*card_size_in_words); cl->do_MemRegion(cur_cards); } } } } } MemRegion CardTableModRefBS::dirty_card_range_after_reset(MemRegion mr, bool reset, int reset_val) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (!mri.is_empty()) { jbyte* cur_entry, *next_entry, *limit; for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last()); cur_entry <= limit; cur_entry = next_entry) { next_entry = cur_entry + 1; if (*cur_entry == dirty_card) { size_t dirty_cards; // Accumulate maximal dirty card range, starting at cur_entry for (dirty_cards = 1; next_entry <= limit && *next_entry == dirty_card; dirty_cards++, next_entry++); MemRegion cur_cards(addr_for(cur_entry), dirty_cards*card_size_in_words); if (reset) { for (size_t i = 0; i < dirty_cards; i++) { cur_entry[i] = reset_val; } } return cur_cards; } } } } return MemRegion(mr.end(), mr.end()); } // Set all the dirty cards in the given region to "precleaned" state. void CardTableModRefBS::preclean_dirty_cards(MemRegion mr) { for (int i = 0; i < _cur_covered_regions; i++) { MemRegion mri = mr.intersection(_covered[i]); if (!mri.is_empty()) { jbyte *cur_entry, *limit; for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last()); cur_entry <= limit; cur_entry++) { if (*cur_entry == dirty_card) { *cur_entry = precleaned_card; } } } } } uintx CardTableModRefBS::ct_max_alignment_constraint() { return card_size * os::vm_page_size(); } void CardTableModRefBS::verify_guard() { // For product build verification guarantee(_byte_map[_guard_index] == last_card, "card table guard has been modified"); } void CardTableModRefBS::verify() { verify_guard(); } #ifndef PRODUCT class GuaranteeNotModClosure: public MemRegionClosure { CardTableModRefBS* _ct; public: GuaranteeNotModClosure(CardTableModRefBS* ct) : _ct(ct) {} void do_MemRegion(MemRegion mr) { jbyte* entry = _ct->byte_for(mr.start()); guarantee(*entry != CardTableModRefBS::clean_card, "Dirty card in region that should be clean"); } }; void CardTableModRefBS::verify_clean_region(MemRegion mr) { GuaranteeNotModClosure blk(this); non_clean_card_iterate_work(mr, &blk, false); } #endif bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) { return CardTableModRefBS::card_will_be_scanned(cv) || _rs->is_prev_nonclean_card_val(cv); }; bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) { return cv != clean_card && (CardTableModRefBS::card_may_have_been_dirty(cv) || CardTableRS::youngergen_may_have_been_dirty(cv)); };