--- old/src/share/vm/gc/parallel/cardTableExtension.cpp 2017-04-25 16:46:48.715170535 +0200 +++ /dev/null 2017-03-07 11:44:12.271151064 +0100 @@ -1,681 +0,0 @@ -/* - * Copyright (c) 2001, 2016, 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/parallel/cardTableExtension.hpp" -#include "gc/parallel/gcTaskManager.hpp" -#include "gc/parallel/objectStartArray.inline.hpp" -#include "gc/parallel/parallelScavengeHeap.hpp" -#include "gc/parallel/psPromotionManager.inline.hpp" -#include "gc/parallel/psScavenge.hpp" -#include "gc/parallel/psTasks.hpp" -#include "gc/parallel/psYoungGen.hpp" -#include "oops/oop.inline.hpp" -#include "runtime/prefetch.inline.hpp" - -// Checks an individual oop for missing precise marks. Mark -// may be either dirty or newgen. -class CheckForUnmarkedOops : public OopClosure { - private: - PSYoungGen* _young_gen; - CardTableExtension* _card_table; - HeapWord* _unmarked_addr; - - protected: - template void do_oop_work(T* p) { - oop obj = oopDesc::load_decode_heap_oop(p); - if (_young_gen->is_in_reserved(obj) && - !_card_table->addr_is_marked_imprecise(p)) { - // Don't overwrite the first missing card mark - if (_unmarked_addr == NULL) { - _unmarked_addr = (HeapWord*)p; - } - } - } - - public: - CheckForUnmarkedOops(PSYoungGen* young_gen, CardTableExtension* card_table) : - _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { } - - virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); } - virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); } - - bool has_unmarked_oop() { - return _unmarked_addr != NULL; - } -}; - -// Checks all objects for the existence of some type of mark, -// precise or imprecise, dirty or newgen. -class CheckForUnmarkedObjects : public ObjectClosure { - private: - PSYoungGen* _young_gen; - CardTableExtension* _card_table; - - public: - CheckForUnmarkedObjects() { - ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); - _young_gen = heap->young_gen(); - _card_table = barrier_set_cast(heap->barrier_set()); - // No point in asserting barrier set type here. Need to make CardTableExtension - // a unique barrier set type. - } - - // Card marks are not precise. The current system can leave us with - // a mismatch of precise marks and beginning of object marks. This means - // we test for missing precise marks first. If any are found, we don't - // fail unless the object head is also unmarked. - virtual void do_object(oop obj) { - CheckForUnmarkedOops object_check(_young_gen, _card_table); - obj->oop_iterate_no_header(&object_check); - if (object_check.has_unmarked_oop()) { - guarantee(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object"); - } - } -}; - -// Checks for precise marking of oops as newgen. -class CheckForPreciseMarks : public OopClosure { - private: - PSYoungGen* _young_gen; - CardTableExtension* _card_table; - - protected: - template void do_oop_work(T* p) { - oop obj = oopDesc::load_decode_heap_oop_not_null(p); - if (_young_gen->is_in_reserved(obj)) { - assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop"); - _card_table->set_card_newgen(p); - } - } - - public: - CheckForPreciseMarks( PSYoungGen* young_gen, CardTableExtension* card_table ) : - _young_gen(young_gen), _card_table(card_table) { } - - virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); } - virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); } -}; - -// We get passed the space_top value to prevent us from traversing into -// the old_gen promotion labs, which cannot be safely parsed. - -// Do not call this method if the space is empty. -// It is a waste to start tasks and get here only to -// do no work. If this method needs to be called -// when the space is empty, fix the calculation of -// end_card to allow sp_top == sp->bottom(). - -void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array, - MutableSpace* sp, - HeapWord* space_top, - PSPromotionManager* pm, - uint stripe_number, - uint stripe_total) { - int ssize = 128; // Naked constant! Work unit = 64k. - int dirty_card_count = 0; - - // It is a waste to get here if empty. - assert(sp->bottom() < sp->top(), "Should not be called if empty"); - oop* sp_top = (oop*)space_top; - jbyte* start_card = byte_for(sp->bottom()); - jbyte* end_card = byte_for(sp_top - 1) + 1; - oop* last_scanned = NULL; // Prevent scanning objects more than once - // The width of the stripe ssize*stripe_total must be - // consistent with the number of stripes so that the complete slice - // is covered. - size_t slice_width = ssize * stripe_total; - for (jbyte* slice = start_card; slice < end_card; slice += slice_width) { - jbyte* worker_start_card = slice + stripe_number * ssize; - if (worker_start_card >= end_card) - return; // We're done. - - jbyte* worker_end_card = worker_start_card + ssize; - if (worker_end_card > end_card) - worker_end_card = end_card; - - // We do not want to scan objects more than once. In order to accomplish - // this, we assert that any object with an object head inside our 'slice' - // belongs to us. We may need to extend the range of scanned cards if the - // last object continues into the next 'slice'. - // - // Note! ending cards are exclusive! - HeapWord* slice_start = addr_for(worker_start_card); - HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); - -#ifdef ASSERT - if (GCWorkerDelayMillis > 0) { - // Delay 1 worker so that it proceeds after all the work - // has been completed. - if (stripe_number < 2) { - os::sleep(Thread::current(), GCWorkerDelayMillis, false); - } - } -#endif - - // If there are not objects starting within the chunk, skip it. - if (!start_array->object_starts_in_range(slice_start, slice_end)) { - continue; - } - // Update our beginning addr - HeapWord* first_object = start_array->object_start(slice_start); - debug_only(oop* first_object_within_slice = (oop*) first_object;) - if (first_object < slice_start) { - last_scanned = (oop*)(first_object + oop(first_object)->size()); - debug_only(first_object_within_slice = last_scanned;) - worker_start_card = byte_for(last_scanned); - } - - // Update the ending addr - if (slice_end < (HeapWord*)sp_top) { - // The subtraction is important! An object may start precisely at slice_end. - HeapWord* last_object = start_array->object_start(slice_end - 1); - slice_end = last_object + oop(last_object)->size(); - // worker_end_card is exclusive, so bump it one past the end of last_object's - // covered span. - worker_end_card = byte_for(slice_end) + 1; - - if (worker_end_card > end_card) - worker_end_card = end_card; - } - - assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); - assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); - assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); - // Note that worker_start_card >= worker_end_card is legal, and happens when - // an object spans an entire slice. - assert(worker_start_card <= end_card, "worker start card beyond end card"); - assert(worker_end_card <= end_card, "worker end card beyond end card"); - - jbyte* current_card = worker_start_card; - while (current_card < worker_end_card) { - // Find an unclean card. - while (current_card < worker_end_card && card_is_clean(*current_card)) { - current_card++; - } - jbyte* first_unclean_card = current_card; - - // Find the end of a run of contiguous unclean cards - while (current_card < worker_end_card && !card_is_clean(*current_card)) { - while (current_card < worker_end_card && !card_is_clean(*current_card)) { - current_card++; - } - - if (current_card < worker_end_card) { - // Some objects may be large enough to span several cards. If such - // an object has more than one dirty card, separated by a clean card, - // we will attempt to scan it twice. The test against "last_scanned" - // prevents the redundant object scan, but it does not prevent newly - // marked cards from being cleaned. - HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); - size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); - HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; - jbyte* ending_card_of_last_object = byte_for(end_of_last_object); - assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); - if (ending_card_of_last_object > current_card) { - // This means the object spans the next complete card. - // We need to bump the current_card to ending_card_of_last_object - current_card = ending_card_of_last_object; - } - } - } - jbyte* following_clean_card = current_card; - - if (first_unclean_card < worker_end_card) { - oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); - assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); - // "p" should always be >= "last_scanned" because newly GC dirtied - // cards are no longer scanned again (see comment at end - // of loop on the increment of "current_card"). Test that - // hypothesis before removing this code. - // If this code is removed, deal with the first time through - // the loop when the last_scanned is the object starting in - // the previous slice. - assert((p >= last_scanned) || - (last_scanned == first_object_within_slice), - "Should no longer be possible"); - if (p < last_scanned) { - // Avoid scanning more than once; this can happen because - // newgen cards set by GC may a different set than the - // originally dirty set - p = last_scanned; - } - oop* to = (oop*)addr_for(following_clean_card); - - // Test slice_end first! - if ((HeapWord*)to > slice_end) { - to = (oop*)slice_end; - } else if (to > sp_top) { - to = sp_top; - } - - // we know which cards to scan, now clear them - if (first_unclean_card <= worker_start_card+1) - first_unclean_card = worker_start_card+1; - if (following_clean_card >= worker_end_card-1) - following_clean_card = worker_end_card-1; - - while (first_unclean_card < following_clean_card) { - *first_unclean_card++ = clean_card; - } - - const int interval = PrefetchScanIntervalInBytes; - // scan all objects in the range - if (interval != 0) { - while (p < to) { - Prefetch::write(p, interval); - oop m = oop(p); - assert(m->is_oop_or_null(), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); - pm->push_contents(m); - p += m->size(); - } - pm->drain_stacks_cond_depth(); - } else { - while (p < to) { - oop m = oop(p); - assert(m->is_oop_or_null(), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); - pm->push_contents(m); - p += m->size(); - } - pm->drain_stacks_cond_depth(); - } - last_scanned = p; - } - // "current_card" is still the "following_clean_card" or - // the current_card is >= the worker_end_card so the - // loop will not execute again. - assert((current_card == following_clean_card) || - (current_card >= worker_end_card), - "current_card should only be incremented if it still equals " - "following_clean_card"); - // Increment current_card so that it is not processed again. - // It may now be dirty because a old-to-young pointer was - // found on it an updated. If it is now dirty, it cannot be - // be safely cleaned in the next iteration. - current_card++; - } - } -} - -// This should be called before a scavenge. -void CardTableExtension::verify_all_young_refs_imprecise() { - CheckForUnmarkedObjects check; - - ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); - PSOldGen* old_gen = heap->old_gen(); - - old_gen->object_iterate(&check); -} - -// This should be called immediately after a scavenge, before mutators resume. -void CardTableExtension::verify_all_young_refs_precise() { - ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); - PSOldGen* old_gen = heap->old_gen(); - - CheckForPreciseMarks check( - heap->young_gen(), - barrier_set_cast(heap->barrier_set())); - - old_gen->oop_iterate_no_header(&check); - - verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); -} - -void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) { - CardTableExtension* card_table = - barrier_set_cast(ParallelScavengeHeap::heap()->barrier_set()); - - jbyte* bot = card_table->byte_for(mr.start()); - jbyte* top = card_table->byte_for(mr.end()); - while(bot <= top) { - assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); - if (*bot == verify_card) - *bot = youngergen_card; - bot++; - } -} - -bool CardTableExtension::addr_is_marked_imprecise(void *addr) { - jbyte* p = byte_for(addr); - jbyte val = *p; - - if (card_is_dirty(val)) - return true; - - if (card_is_newgen(val)) - return true; - - if (card_is_clean(val)) - return false; - - assert(false, "Found unhandled card mark type"); - - return false; -} - -// Also includes verify_card -bool CardTableExtension::addr_is_marked_precise(void *addr) { - jbyte* p = byte_for(addr); - jbyte val = *p; - - if (card_is_newgen(val)) - return true; - - if (card_is_verify(val)) - return true; - - if (card_is_clean(val)) - return false; - - if (card_is_dirty(val)) - return false; - - assert(false, "Found unhandled card mark type"); - - return false; -} - -// Assumes that only the base or the end changes. This allows indentification -// of the region that is being resized. The -// CardTableModRefBS::resize_covered_region() is used for the normal case -// where the covered regions are growing or shrinking at the high end. -// The method resize_covered_region_by_end() is analogous to -// CardTableModRefBS::resize_covered_region() but -// for regions that grow or shrink at the low end. -void CardTableExtension::resize_covered_region(MemRegion new_region) { - - for (int i = 0; i < _cur_covered_regions; i++) { - if (_covered[i].start() == new_region.start()) { - // Found a covered region with the same start as the - // new region. The region is growing or shrinking - // from the start of the region. - resize_covered_region_by_start(new_region); - return; - } - if (_covered[i].start() > new_region.start()) { - break; - } - } - - int changed_region = -1; - for (int j = 0; j < _cur_covered_regions; j++) { - if (_covered[j].end() == new_region.end()) { - changed_region = j; - // This is a case where the covered region is growing or shrinking - // at the start of the region. - assert(changed_region != -1, "Don't expect to add a covered region"); - assert(_covered[changed_region].byte_size() != new_region.byte_size(), - "The sizes should be different here"); - resize_covered_region_by_end(changed_region, new_region); - return; - } - } - // This should only be a new covered region (where no existing - // covered region matches at the start or the end). - assert(_cur_covered_regions < _max_covered_regions, - "An existing region should have been found"); - resize_covered_region_by_start(new_region); -} - -void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) { - CardTableModRefBS::resize_covered_region(new_region); - debug_only(verify_guard();) -} - -void CardTableExtension::resize_covered_region_by_end(int changed_region, - MemRegion new_region) { - assert(SafepointSynchronize::is_at_safepoint(), - "Only expect an expansion at the low end at a GC"); - debug_only(verify_guard();) -#ifdef ASSERT - for (int k = 0; k < _cur_covered_regions; k++) { - if (_covered[k].end() == new_region.end()) { - assert(changed_region == k, "Changed region is incorrect"); - break; - } - } -#endif - - // Commit new or uncommit old pages, if necessary. - if (resize_commit_uncommit(changed_region, new_region)) { - // Set the new start of the committed region - resize_update_committed_table(changed_region, new_region); - } - - // Update card table entries - resize_update_card_table_entries(changed_region, new_region); - - // Update the covered region - resize_update_covered_table(changed_region, new_region); - - int ind = changed_region; - log_trace(gc, barrier)("CardTableModRefBS::resize_covered_region: "); - log_trace(gc, barrier)(" _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, - ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last())); - log_trace(gc, barrier)(" _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, - ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last())); - log_trace(gc, barrier)(" byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, - p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last()))); - log_trace(gc, barrier)(" addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT, - p2i(addr_for((jbyte*) _committed[ind].start())), p2i(addr_for((jbyte*) _committed[ind].last()))); - - debug_only(verify_guard();) -} - -bool CardTableExtension::resize_commit_uncommit(int changed_region, - MemRegion new_region) { - bool result = false; - // Commit new or uncommit old pages, if necessary. - MemRegion cur_committed = _committed[changed_region]; - assert(_covered[changed_region].end() == new_region.end(), - "The ends of the regions are expected to match"); - // Extend the start of this _committed region to - // to cover the start of any previous _committed region. - // This forms overlapping regions, but never interior regions. - HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); - if (min_prev_start < cur_committed.start()) { - // Only really need to set start of "cur_committed" to - // the new start (min_prev_start) but assertion checking code - // below use cur_committed.end() so make it correct. - MemRegion new_committed = - MemRegion(min_prev_start, cur_committed.end()); - cur_committed = new_committed; - } -#ifdef ASSERT - ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); - assert(cur_committed.start() == - (HeapWord*) align_size_up((uintptr_t) cur_committed.start(), - os::vm_page_size()), - "Starts should have proper alignment"); -#endif - - jbyte* new_start = byte_for(new_region.start()); - // Round down because this is for the start address - HeapWord* new_start_aligned = - (HeapWord*)align_size_down((uintptr_t)new_start, os::vm_page_size()); - // The guard page is always committed and should not be committed over. - // This method is used in cases where the generation is growing toward - // lower addresses but the guard region is still at the end of the - // card table. That still makes sense when looking for writes - // off the end of the card table. - if (new_start_aligned < cur_committed.start()) { - // Expand the committed region - // - // Case A - // |+ guard +| - // |+ cur committed +++++++++| - // |+ new committed +++++++++++++++++| - // - // Case B - // |+ guard +| - // |+ cur committed +| - // |+ new committed +++++++| - // - // These are not expected because the calculation of the - // cur committed region and the new committed region - // share the same end for the covered region. - // Case C - // |+ guard +| - // |+ cur committed +| - // |+ new committed +++++++++++++++++| - // Case D - // |+ guard +| - // |+ cur committed +++++++++++| - // |+ new committed +++++++| - - HeapWord* new_end_for_commit = - MIN2(cur_committed.end(), _guard_region.start()); - if(new_start_aligned < new_end_for_commit) { - MemRegion new_committed = - MemRegion(new_start_aligned, new_end_for_commit); - os::commit_memory_or_exit((char*)new_committed.start(), - new_committed.byte_size(), !ExecMem, - "card table expansion"); - } - result = true; - } else if (new_start_aligned > cur_committed.start()) { - // Shrink the committed region -#if 0 // uncommitting space is currently unsafe because of the interactions - // of growing and shrinking regions. One region A can uncommit space - // that it owns but which is being used by another region B (maybe). - // Region B has not committed the space because it was already - // committed by region A. - MemRegion uncommit_region = committed_unique_to_self(changed_region, - MemRegion(cur_committed.start(), new_start_aligned)); - if (!uncommit_region.is_empty()) { - if (!os::uncommit_memory((char*)uncommit_region.start(), - uncommit_region.byte_size())) { - // If the uncommit fails, ignore it. Let the - // committed table resizing go even though the committed - // table will over state the committed space. - } - } -#else - assert(!result, "Should be false with current workaround"); -#endif - } - assert(_committed[changed_region].end() == cur_committed.end(), - "end should not change"); - return result; -} - -void CardTableExtension::resize_update_committed_table(int changed_region, - MemRegion new_region) { - - jbyte* new_start = byte_for(new_region.start()); - // Set the new start of the committed region - HeapWord* new_start_aligned = - (HeapWord*)align_size_down((uintptr_t)new_start, - os::vm_page_size()); - MemRegion new_committed = MemRegion(new_start_aligned, - _committed[changed_region].end()); - _committed[changed_region] = new_committed; - _committed[changed_region].set_start(new_start_aligned); -} - -void CardTableExtension::resize_update_card_table_entries(int changed_region, - MemRegion new_region) { - debug_only(verify_guard();) - MemRegion original_covered = _covered[changed_region]; - // Initialize the card entries. Only consider the - // region covered by the card table (_whole_heap) - jbyte* entry; - if (new_region.start() < _whole_heap.start()) { - entry = byte_for(_whole_heap.start()); - } else { - entry = byte_for(new_region.start()); - } - jbyte* end = byte_for(original_covered.start()); - // If _whole_heap starts at the original covered regions start, - // this loop will not execute. - while (entry < end) { *entry++ = clean_card; } -} - -void CardTableExtension::resize_update_covered_table(int changed_region, - MemRegion new_region) { - // Update the covered region - _covered[changed_region].set_start(new_region.start()); - _covered[changed_region].set_word_size(new_region.word_size()); - - // reorder regions. There should only be at most 1 out - // of order. - for (int i = _cur_covered_regions-1 ; i > 0; i--) { - if (_covered[i].start() < _covered[i-1].start()) { - MemRegion covered_mr = _covered[i-1]; - _covered[i-1] = _covered[i]; - _covered[i] = covered_mr; - MemRegion committed_mr = _committed[i-1]; - _committed[i-1] = _committed[i]; - _committed[i] = committed_mr; - break; - } - } -#ifdef ASSERT - for (int m = 0; m < _cur_covered_regions-1; m++) { - assert(_covered[m].start() <= _covered[m+1].start(), - "Covered regions out of order"); - assert(_committed[m].start() <= _committed[m+1].start(), - "Committed regions out of order"); - } -#endif -} - -// Returns the start of any committed region that is lower than -// the target committed region (index ind) and that intersects the -// target region. If none, return start of target region. -// -// ------------- -// | | -// ------------- -// ------------ -// | target | -// ------------ -// ------------- -// | | -// ------------- -// ^ returns this -// -// ------------- -// | | -// ------------- -// ------------ -// | target | -// ------------ -// ------------- -// | | -// ------------- -// ^ returns this - -HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const { - assert(_cur_covered_regions >= 0, "Expecting at least on region"); - HeapWord* min_start = _committed[ind].start(); - for (int j = 0; j < ind; j++) { - HeapWord* this_start = _committed[j].start(); - if ((this_start < min_start) && - !(_committed[j].intersection(_committed[ind])).is_empty()) { - min_start = this_start; - } - } - return min_start; -}