diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/memory/cardTableModRefBS.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/src/share/vm/memory/cardTableModRefBS.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,547 @@ +/* + * Copyright 2000-2006 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::page_size_for_region(_guard_index + 1, _guard_index + 1, 1)), + _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();) + int ind = find_covering_region_by_base(new_region.start()); + MemRegion 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* 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* 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"); + // The guard page is always committed and should not be committed over. + HeapWord* new_end_for_commit = MIN2(new_end_aligned, _guard_region.start()); + if (new_end_for_commit > cur_committed.end()) { + // Must commit new pages. + MemRegion 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 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())) { + // Do better than this for Merlin + vm_exit_out_of_memory(uncommit_region.byte_size(), + "card table contraction"); + } + } + } + // 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()) < (int) _guard_index, + "The guard card will be overwritten"); + jbyte* end = byte_after(new_region.last()); + // do nothing if we resized downward. + 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(oop* field, oop newVal) { + inline_write_ref_field(field, newVal); +} + + +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) { + 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); + } +} + +// NOTES: +// (1) Unlike mod_oop_in_space_iterate() above, dirty_card_iterate() +// iterates over dirty cards ranges in increasing address order. +// (2) Unlike, e.g., dirty_card_range_after_preclean() below, +// this method does not make the dirty cards prelceaned. +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_preclean(MemRegion mr) { + 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); + for (size_t i = 0; i < dirty_cards; i++) { + cur_entry[i] = precleaned_card; + } + 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)); +};