author | phh |
Sat, 30 Nov 2019 14:33:05 -0800 | |
changeset 59330 | 5b96c12f909d |
parent 58980 | 47c20fc6a517 |
permissions | -rw-r--r-- |
1 | 1 |
/* |
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* Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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||
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#include "precompiled.hpp" |
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#include "classfile/systemDictionary.hpp" |
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#include "gc/parallel/objectStartArray.hpp" |
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#include "gc/parallel/parallelScavengeHeap.hpp" |
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#include "gc/parallel/parMarkBitMap.inline.hpp" |
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#include "gc/parallel/psMarkSweep.hpp" |
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#include "gc/parallel/psMarkSweepDecorator.hpp" |
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#include "gc/parallel/psParallelCompact.inline.hpp" |
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#include "gc/serial/markSweep.inline.hpp" |
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#include "gc/shared/spaceDecorator.inline.hpp" |
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#include "memory/iterator.inline.hpp" |
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#include "oops/oop.inline.hpp" |
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#include "runtime/prefetch.inline.hpp" |
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PSMarkSweepDecorator* PSMarkSweepDecorator::_destination_decorator = NULL; |
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||
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||
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void PSMarkSweepDecorator::set_destination_decorator_tenured() { |
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ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); |
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_destination_decorator = heap->old_gen()->object_mark_sweep(); |
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} |
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void PSMarkSweepDecorator::advance_destination_decorator() { |
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ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); |
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assert(_destination_decorator != NULL, "Sanity"); |
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PSMarkSweepDecorator* first = heap->old_gen()->object_mark_sweep(); |
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PSMarkSweepDecorator* second = heap->young_gen()->eden_mark_sweep(); |
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PSMarkSweepDecorator* third = heap->young_gen()->from_mark_sweep(); |
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PSMarkSweepDecorator* fourth = heap->young_gen()->to_mark_sweep(); |
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if ( _destination_decorator == first ) { |
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_destination_decorator = second; |
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} else if ( _destination_decorator == second ) { |
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_destination_decorator = third; |
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} else if ( _destination_decorator == third ) { |
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_destination_decorator = fourth; |
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} else { |
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fatal("PSMarkSweep attempting to advance past last compaction area"); |
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} |
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} |
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PSMarkSweepDecorator* PSMarkSweepDecorator::destination_decorator() { |
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assert(_destination_decorator != NULL, "Sanity"); |
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return _destination_decorator; |
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} |
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// FIX ME FIX ME FIX ME FIX ME!!!!!!!!! |
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// The object forwarding code is duplicated. Factor this out!!!!! |
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// |
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// This method "precompacts" objects inside its space to dest. It places forwarding |
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// pointers into markWords for use by adjust_pointers. If "dest" should overflow, we |
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// finish by compacting into our own space. |
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void PSMarkSweepDecorator::precompact() { |
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// Reset our own compact top. |
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set_compaction_top(space()->bottom()); |
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/* We allow some amount of garbage towards the bottom of the space, so |
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* we don't start compacting before there is a significant gain to be made. |
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* Occasionally, we want to ensure a full compaction, which is determined |
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* by the MarkSweepAlwaysCompactCount parameter. This is a significant |
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* performance improvement! |
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*/ |
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bool skip_dead = ((PSMarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0); |
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size_t allowed_deadspace = 0; |
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if (skip_dead) { |
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const size_t ratio = allowed_dead_ratio(); |
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allowed_deadspace = space()->capacity_in_words() * ratio / 100; |
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} |
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// Fetch the current destination decorator |
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PSMarkSweepDecorator* dest = destination_decorator(); |
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ObjectStartArray* start_array = dest->start_array(); |
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HeapWord* compact_top = dest->compaction_top(); |
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HeapWord* compact_end = dest->space()->end(); |
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HeapWord* q = space()->bottom(); |
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HeapWord* t = space()->top(); |
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HeapWord* end_of_live= q; /* One byte beyond the last byte of the last |
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live object. */ |
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HeapWord* first_dead = space()->end(); /* The first dead object. */ |
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const intx interval = PrefetchScanIntervalInBytes; |
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while (q < t) { |
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assert(oop(q)->mark_raw().is_marked() || oop(q)->mark_raw().is_unlocked() || |
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oop(q)->mark_raw().has_bias_pattern(), |
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"these are the only valid states during a mark sweep"); |
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if (oop(q)->is_gc_marked()) { |
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/* prefetch beyond q */ |
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Prefetch::write(q, interval); |
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size_t size = oop(q)->size(); |
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size_t compaction_max_size = pointer_delta(compact_end, compact_top); |
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// This should only happen if a space in the young gen overflows the |
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// old gen. If that should happen, we null out the start_array, because |
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// the young spaces are not covered by one. |
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while(size > compaction_max_size) { |
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// First record the last compact_top |
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dest->set_compaction_top(compact_top); |
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// Advance to the next compaction decorator |
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advance_destination_decorator(); |
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dest = destination_decorator(); |
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// Update compaction info |
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start_array = dest->start_array(); |
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compact_top = dest->compaction_top(); |
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compact_end = dest->space()->end(); |
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assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); |
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assert(compact_end > compact_top, "Must always be space remaining"); |
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compaction_max_size = |
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pointer_delta(compact_end, compact_top); |
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} |
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// store the forwarding pointer into the mark word |
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if (q != compact_top) { |
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oop(q)->forward_to(oop(compact_top)); |
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assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); |
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} else { |
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// if the object isn't moving we can just set the mark to the default |
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// mark and handle it specially later on. |
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oop(q)->init_mark_raw(); |
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assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
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} |
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// Update object start array |
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if (start_array) { |
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start_array->allocate_block(compact_top); |
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} |
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compact_top += size; |
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assert(compact_top <= dest->space()->end(), |
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"Exceeding space in destination"); |
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q += size; |
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end_of_live = q; |
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} else { |
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/* run over all the contiguous dead objects */ |
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HeapWord* end = q; |
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do { |
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/* prefetch beyond end */ |
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Prefetch::write(end, interval); |
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end += oop(end)->size(); |
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} while (end < t && (!oop(end)->is_gc_marked())); |
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/* see if we might want to pretend this object is alive so that |
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* we don't have to compact quite as often. |
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*/ |
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if (allowed_deadspace > 0 && q == compact_top) { |
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size_t sz = pointer_delta(end, q); |
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if (insert_deadspace(allowed_deadspace, q, sz)) { |
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size_t compaction_max_size = pointer_delta(compact_end, compact_top); |
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// This should only happen if a space in the young gen overflows the |
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// old gen. If that should happen, we null out the start_array, because |
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// the young spaces are not covered by one. |
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while (sz > compaction_max_size) { |
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// First record the last compact_top |
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dest->set_compaction_top(compact_top); |
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// Advance to the next compaction decorator |
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advance_destination_decorator(); |
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dest = destination_decorator(); |
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// Update compaction info |
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start_array = dest->start_array(); |
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compact_top = dest->compaction_top(); |
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compact_end = dest->space()->end(); |
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assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); |
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assert(compact_end > compact_top, "Must always be space remaining"); |
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compaction_max_size = |
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pointer_delta(compact_end, compact_top); |
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} |
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// store the forwarding pointer into the mark word |
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if (q != compact_top) { |
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oop(q)->forward_to(oop(compact_top)); |
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assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); |
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} else { |
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// if the object isn't moving we can just set the mark to the default |
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// mark and handle it specially later on. |
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oop(q)->init_mark_raw(); |
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assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
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} |
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// Update object start array |
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if (start_array) { |
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start_array->allocate_block(compact_top); |
1 | 221 |
} |
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compact_top += sz; |
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assert(compact_top <= dest->space()->end(), |
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"Exceeding space in destination"); |
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q = end; |
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end_of_live = end; |
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continue; |
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} |
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} |
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||
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// q is a pointer to a dead object. Use this dead memory to store a pointer to the next live object. |
234 |
(*(HeapWord**)q) = end; |
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1 | 235 |
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/* see if this is the first dead region. */ |
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if (q < first_dead) { |
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first_dead = q; |
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} |
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240 |
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/* move on to the next object */ |
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q = end; |
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} |
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} |
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assert(q == t, "just checking"); |
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_end_of_live = end_of_live; |
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if (end_of_live < first_dead) { |
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first_dead = end_of_live; |
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} |
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_first_dead = first_dead; |
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// Update compaction top |
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dest->set_compaction_top(compact_top); |
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} |
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bool PSMarkSweepDecorator::insert_deadspace(size_t& allowed_deadspace_words, |
258 |
HeapWord* q, size_t deadlength) { |
|
259 |
if (allowed_deadspace_words >= deadlength) { |
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allowed_deadspace_words -= deadlength; |
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CollectedHeap::fill_with_object(q, deadlength); |
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oop(q)->set_mark_raw(oop(q)->mark_raw().set_marked()); |
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assert((int) deadlength == oop(q)->size(), "bad filler object size"); |
1 | 264 |
// Recall that we required "q == compaction_top". |
265 |
return true; |
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266 |
} else { |
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267 |
allowed_deadspace_words = 0; |
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268 |
return false; |
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269 |
} |
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270 |
} |
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271 |
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272 |
void PSMarkSweepDecorator::adjust_pointers() { |
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273 |
// adjust all the interior pointers to point at the new locations of objects |
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274 |
// Used by MarkSweep::mark_sweep_phase3() |
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275 |
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276 |
HeapWord* q = space()->bottom(); |
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277 |
HeapWord* t = _end_of_live; // Established by "prepare_for_compaction". |
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278 |
||
279 |
assert(_first_dead <= _end_of_live, "Stands to reason, no?"); |
|
280 |
||
281 |
if (q < t && _first_dead > q && |
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282 |
!oop(q)->is_gc_marked()) { |
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283 |
// we have a chunk of the space which hasn't moved and we've |
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// reinitialized the mark word during the previous pass, so we can't |
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// use is_gc_marked for the traversal. |
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286 |
HeapWord* end = _first_dead; |
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287 |
||
288 |
while (q < end) { |
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289 |
// point all the oops to the new location |
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size_t size = MarkSweep::adjust_pointers(oop(q)); |
1 | 291 |
q += size; |
292 |
} |
|
293 |
||
294 |
if (_first_dead == t) { |
|
295 |
q = t; |
|
296 |
} else { |
|
37238 | 297 |
// The first dead object should contain a pointer to the first live object |
298 |
q = *(HeapWord**)_first_dead; |
|
1 | 299 |
} |
300 |
} |
|
301 |
const intx interval = PrefetchScanIntervalInBytes; |
|
302 |
||
303 |
debug_only(HeapWord* prev_q = NULL); |
|
304 |
while (q < t) { |
|
305 |
// prefetch beyond q |
|
306 |
Prefetch::write(q, interval); |
|
307 |
if (oop(q)->is_gc_marked()) { |
|
308 |
// q is alive |
|
309 |
// point all the oops to the new location |
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size_t size = MarkSweep::adjust_pointers(oop(q)); |
1 | 311 |
debug_only(prev_q = q); |
312 |
q += size; |
|
313 |
} else { |
|
314 |
debug_only(prev_q = q); |
|
37238 | 315 |
// The first dead object is no longer an object. At that memory address, |
316 |
// there is a pointer to the first live object that the previous phase found. |
|
317 |
q = *(HeapWord**)q; |
|
318 |
assert(q > prev_q, "we should be moving forward through memory, q: " PTR_FORMAT ", prev_q: " PTR_FORMAT, p2i(q), p2i(prev_q)); |
|
1 | 319 |
} |
320 |
} |
|
321 |
||
322 |
assert(q == t, "just checking"); |
|
323 |
} |
|
324 |
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325 |
void PSMarkSweepDecorator::compact(bool mangle_free_space ) { |
|
326 |
// Copy all live objects to their new location |
|
327 |
// Used by MarkSweep::mark_sweep_phase4() |
|
328 |
||
329 |
HeapWord* q = space()->bottom(); |
|
330 |
HeapWord* const t = _end_of_live; |
|
331 |
debug_only(HeapWord* prev_q = NULL); |
|
332 |
||
333 |
if (q < t && _first_dead > q && |
|
334 |
!oop(q)->is_gc_marked()) { |
|
335 |
#ifdef ASSERT |
|
336 |
// we have a chunk of the space which hasn't moved and we've reinitialized the |
|
337 |
// mark word during the previous pass, so we can't use is_gc_marked for the |
|
338 |
// traversal. |
|
339 |
HeapWord* const end = _first_dead; |
|
340 |
||
341 |
while (q < end) { |
|
342 |
size_t size = oop(q)->size(); |
|
343 |
assert(!oop(q)->is_gc_marked(), "should be unmarked (special dense prefix handling)"); |
|
344 |
debug_only(prev_q = q); |
|
345 |
q += size; |
|
346 |
} |
|
347 |
#endif |
|
348 |
||
349 |
if (_first_dead == t) { |
|
350 |
q = t; |
|
351 |
} else { |
|
352 |
// $$$ Funky |
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|
353 |
q = (HeapWord*) oop(_first_dead)->mark_raw().decode_pointer(); |
1 | 354 |
} |
355 |
} |
|
356 |
||
357 |
const intx scan_interval = PrefetchScanIntervalInBytes; |
|
358 |
const intx copy_interval = PrefetchCopyIntervalInBytes; |
|
359 |
||
360 |
while (q < t) { |
|
361 |
if (!oop(q)->is_gc_marked()) { |
|
362 |
// mark is pointer to next marked oop |
|
363 |
debug_only(prev_q = q); |
|
57777
90ead0febf56
8229258: Rework markOop and markOopDesc into a simpler mark word value carrier
stefank
parents:
50752
diff
changeset
|
364 |
q = (HeapWord*) oop(q)->mark_raw().decode_pointer(); |
1 | 365 |
assert(q > prev_q, "we should be moving forward through memory"); |
366 |
} else { |
|
367 |
// prefetch beyond q |
|
368 |
Prefetch::read(q, scan_interval); |
|
369 |
||
370 |
// size and destination |
|
371 |
size_t size = oop(q)->size(); |
|
372 |
HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); |
|
373 |
||
374 |
// prefetch beyond compaction_top |
|
375 |
Prefetch::write(compaction_top, copy_interval); |
|
376 |
||
377 |
// copy object and reinit its mark |
|
378 |
assert(q != compaction_top, "everything in this pass should be moving"); |
|
379 |
Copy::aligned_conjoint_words(q, compaction_top, size); |
|
49722
a47d1e21b3f1
8199735: Mark word updates need to use Access API
rkennke
parents:
47216
diff
changeset
|
380 |
oop(compaction_top)->init_mark_raw(); |
1 | 381 |
assert(oop(compaction_top)->klass() != NULL, "should have a class"); |
382 |
||
383 |
debug_only(prev_q = q); |
|
384 |
q += size; |
|
385 |
} |
|
386 |
} |
|
387 |
||
388 |
assert(compaction_top() >= space()->bottom() && compaction_top() <= space()->end(), |
|
389 |
"should point inside space"); |
|
390 |
space()->set_top(compaction_top()); |
|
391 |
||
971
f0b20be4165d
6672698: mangle_unused_area() should not remangle the entire heap at each collection.
jmasa
parents:
360
diff
changeset
|
392 |
if (mangle_free_space) { |
f0b20be4165d
6672698: mangle_unused_area() should not remangle the entire heap at each collection.
jmasa
parents:
360
diff
changeset
|
393 |
space()->mangle_unused_area(); |
f0b20be4165d
6672698: mangle_unused_area() should not remangle the entire heap at each collection.
jmasa
parents:
360
diff
changeset
|
394 |
} |
1 | 395 |
} |