--- old/src/share/vm/memory/cardGeneration.cpp 2015-05-12 11:56:32.145026929 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,360 +0,0 @@ -/* - * Copyright (c) 2014, 2015, 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 "memory/blockOffsetTable.inline.hpp" -#include "memory/cardGeneration.inline.hpp" -#include "memory/gcLocker.hpp" -#include "memory/generationSpec.hpp" -#include "memory/genOopClosures.inline.hpp" -#include "memory/genRemSet.hpp" -#include "memory/iterator.hpp" -#include "memory/memRegion.hpp" -#include "memory/space.inline.hpp" -#include "runtime/java.hpp" - -CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size, - int level, - GenRemSet* remset) : - Generation(rs, initial_byte_size, level), _rs(remset), - _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(), - _used_at_prologue() -{ - HeapWord* start = (HeapWord*)rs.base(); - size_t reserved_byte_size = rs.size(); - assert((uintptr_t(start) & 3) == 0, "bad alignment"); - assert((reserved_byte_size & 3) == 0, "bad alignment"); - MemRegion reserved_mr(start, heap_word_size(reserved_byte_size)); - _bts = new BlockOffsetSharedArray(reserved_mr, - heap_word_size(initial_byte_size)); - MemRegion committed_mr(start, heap_word_size(initial_byte_size)); - _rs->resize_covered_region(committed_mr); - if (_bts == NULL) { - vm_exit_during_initialization("Could not allocate a BlockOffsetArray"); - } - - // Verify that the start and end of this generation is the start of a card. - // If this wasn't true, a single card could span more than on generation, - // which would cause problems when we commit/uncommit memory, and when we - // clear and dirty cards. - guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned"); - if (reserved_mr.end() != GenCollectedHeap::heap()->reserved_region().end()) { - // Don't check at the very end of the heap as we'll assert that we're probing off - // the end if we try. - guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned"); - } - _min_heap_delta_bytes = MinHeapDeltaBytes; - _capacity_at_prologue = initial_byte_size; - _used_at_prologue = 0; -} - -bool CardGeneration::grow_by(size_t bytes) { - assert_correct_size_change_locking(); - bool result = _virtual_space.expand_by(bytes); - if (result) { - size_t new_word_size = - heap_word_size(_virtual_space.committed_size()); - MemRegion mr(space()->bottom(), new_word_size); - // Expand card table - GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr); - // Expand shared block offset array - _bts->resize(new_word_size); - - // Fix for bug #4668531 - if (ZapUnusedHeapArea) { - MemRegion mangle_region(space()->end(), - (HeapWord*)_virtual_space.high()); - SpaceMangler::mangle_region(mangle_region); - } - - // Expand space -- also expands space's BOT - // (which uses (part of) shared array above) - space()->set_end((HeapWord*)_virtual_space.high()); - - // update the space and generation capacity counters - update_counters(); - - if (Verbose && PrintGC) { - size_t new_mem_size = _virtual_space.committed_size(); - size_t old_mem_size = new_mem_size - bytes; - gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " - SIZE_FORMAT "K to " SIZE_FORMAT "K", - name(), old_mem_size/K, bytes/K, new_mem_size/K); - } - } - return result; -} - -bool CardGeneration::expand(size_t bytes, size_t expand_bytes) { - assert_locked_or_safepoint(Heap_lock); - if (bytes == 0) { - return true; // That's what grow_by(0) would return - } - size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes); - if (aligned_bytes == 0){ - // The alignment caused the number of bytes to wrap. An expand_by(0) will - // return true with the implication that an expansion was done when it - // was not. A call to expand implies a best effort to expand by "bytes" - // but not a guarantee. Align down to give a best effort. This is likely - // the most that the generation can expand since it has some capacity to - // start with. - aligned_bytes = ReservedSpace::page_align_size_down(bytes); - } - size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); - bool success = false; - if (aligned_expand_bytes > aligned_bytes) { - success = grow_by(aligned_expand_bytes); - } - if (!success) { - success = grow_by(aligned_bytes); - } - if (!success) { - success = grow_to_reserved(); - } - if (PrintGC && Verbose) { - if (success && GC_locker::is_active_and_needs_gc()) { - gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead"); - } - } - - return success; -} - -bool CardGeneration::grow_to_reserved() { - assert_correct_size_change_locking(); - bool success = true; - const size_t remaining_bytes = _virtual_space.uncommitted_size(); - if (remaining_bytes > 0) { - success = grow_by(remaining_bytes); - DEBUG_ONLY(if (!success) warning("grow to reserved failed");) - } - return success; -} - -void CardGeneration::shrink(size_t bytes) { - assert_correct_size_change_locking(); - - size_t size = ReservedSpace::page_align_size_down(bytes); - if (size == 0) { - return; - } - - // Shrink committed space - _virtual_space.shrink_by(size); - // Shrink space; this also shrinks the space's BOT - space()->set_end((HeapWord*) _virtual_space.high()); - size_t new_word_size = heap_word_size(space()->capacity()); - // Shrink the shared block offset array - _bts->resize(new_word_size); - MemRegion mr(space()->bottom(), new_word_size); - // Shrink the card table - GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr); - - if (Verbose && PrintGC) { - size_t new_mem_size = _virtual_space.committed_size(); - size_t old_mem_size = new_mem_size + size; - gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", - name(), old_mem_size/K, new_mem_size/K); - } -} - -// No young generation references, clear this generation's cards. -void CardGeneration::clear_remembered_set() { - _rs->clear(reserved()); -} - -// Objects in this generation may have moved, invalidate this -// generation's cards. -void CardGeneration::invalidate_remembered_set() { - _rs->invalidate(used_region()); -} - -void CardGeneration::compute_new_size() { - assert(_shrink_factor <= 100, "invalid shrink factor"); - size_t current_shrink_factor = _shrink_factor; - _shrink_factor = 0; - - // We don't have floating point command-line arguments - // Note: argument processing ensures that MinHeapFreeRatio < 100. - const double minimum_free_percentage = MinHeapFreeRatio / 100.0; - const double maximum_used_percentage = 1.0 - minimum_free_percentage; - - // Compute some numbers about the state of the heap. - const size_t used_after_gc = used(); - const size_t capacity_after_gc = capacity(); - - const double min_tmp = used_after_gc / maximum_used_percentage; - size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx)); - // Don't shrink less than the initial generation size - minimum_desired_capacity = MAX2(minimum_desired_capacity, - spec()->init_size()); - assert(used_after_gc <= minimum_desired_capacity, "sanity check"); - - if (PrintGC && Verbose) { - const size_t free_after_gc = free(); - const double free_percentage = ((double)free_after_gc) / capacity_after_gc; - gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: "); - gclog_or_tty->print_cr(" " - " minimum_free_percentage: %6.2f" - " maximum_used_percentage: %6.2f", - minimum_free_percentage, - maximum_used_percentage); - gclog_or_tty->print_cr(" " - " free_after_gc : %6.1fK" - " used_after_gc : %6.1fK" - " capacity_after_gc : %6.1fK", - free_after_gc / (double) K, - used_after_gc / (double) K, - capacity_after_gc / (double) K); - gclog_or_tty->print_cr(" " - " free_percentage: %6.2f", - free_percentage); - } - - if (capacity_after_gc < minimum_desired_capacity) { - // If we have less free space than we want then expand - size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; - // Don't expand unless it's significant - if (expand_bytes >= _min_heap_delta_bytes) { - expand(expand_bytes, 0); // safe if expansion fails - } - if (PrintGC && Verbose) { - gclog_or_tty->print_cr(" expanding:" - " minimum_desired_capacity: %6.1fK" - " expand_bytes: %6.1fK" - " _min_heap_delta_bytes: %6.1fK", - minimum_desired_capacity / (double) K, - expand_bytes / (double) K, - _min_heap_delta_bytes / (double) K); - } - return; - } - - // No expansion, now see if we want to shrink - size_t shrink_bytes = 0; - // We would never want to shrink more than this - size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity; - - if (MaxHeapFreeRatio < 100) { - const double maximum_free_percentage = MaxHeapFreeRatio / 100.0; - const double minimum_used_percentage = 1.0 - maximum_free_percentage; - const double max_tmp = used_after_gc / minimum_used_percentage; - size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx)); - maximum_desired_capacity = MAX2(maximum_desired_capacity, - spec()->init_size()); - if (PrintGC && Verbose) { - gclog_or_tty->print_cr(" " - " maximum_free_percentage: %6.2f" - " minimum_used_percentage: %6.2f", - maximum_free_percentage, - minimum_used_percentage); - gclog_or_tty->print_cr(" " - " _capacity_at_prologue: %6.1fK" - " minimum_desired_capacity: %6.1fK" - " maximum_desired_capacity: %6.1fK", - _capacity_at_prologue / (double) K, - minimum_desired_capacity / (double) K, - maximum_desired_capacity / (double) K); - } - assert(minimum_desired_capacity <= maximum_desired_capacity, - "sanity check"); - - if (capacity_after_gc > maximum_desired_capacity) { - // Capacity too large, compute shrinking size - shrink_bytes = capacity_after_gc - maximum_desired_capacity; - // We don't want shrink all the way back to initSize if people call - // System.gc(), because some programs do that between "phases" and then - // we'd just have to grow the heap up again for the next phase. So we - // damp the shrinking: 0% on the first call, 10% on the second call, 40% - // on the third call, and 100% by the fourth call. But if we recompute - // size without shrinking, it goes back to 0%. - shrink_bytes = shrink_bytes / 100 * current_shrink_factor; - assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); - if (current_shrink_factor == 0) { - _shrink_factor = 10; - } else { - _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100); - } - if (PrintGC && Verbose) { - gclog_or_tty->print_cr(" " - " shrinking:" - " initSize: %.1fK" - " maximum_desired_capacity: %.1fK", - spec()->init_size() / (double) K, - maximum_desired_capacity / (double) K); - gclog_or_tty->print_cr(" " - " shrink_bytes: %.1fK" - " current_shrink_factor: " SIZE_FORMAT - " new shrink factor: " SIZE_FORMAT - " _min_heap_delta_bytes: %.1fK", - shrink_bytes / (double) K, - current_shrink_factor, - _shrink_factor, - _min_heap_delta_bytes / (double) K); - } - } - } - - if (capacity_after_gc > _capacity_at_prologue) { - // We might have expanded for promotions, in which case we might want to - // take back that expansion if there's room after GC. That keeps us from - // stretching the heap with promotions when there's plenty of room. - size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue; - expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes); - // We have two shrinking computations, take the largest - shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion); - assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); - if (PrintGC && Verbose) { - gclog_or_tty->print_cr(" " - " aggressive shrinking:" - " _capacity_at_prologue: %.1fK" - " capacity_after_gc: %.1fK" - " expansion_for_promotion: %.1fK" - " shrink_bytes: %.1fK", - capacity_after_gc / (double) K, - _capacity_at_prologue / (double) K, - expansion_for_promotion / (double) K, - shrink_bytes / (double) K); - } - } - // Don't shrink unless it's significant - if (shrink_bytes >= _min_heap_delta_bytes) { - shrink(shrink_bytes); - } -} - -// Currently nothing to do. -void CardGeneration::prepare_for_verify() {} - -void CardGeneration::space_iterate(SpaceClosure* blk, - bool usedOnly) { - blk->do_space(space()); -} - -void CardGeneration::younger_refs_iterate(OopsInGenClosure* blk) { - blk->set_generation(this); - younger_refs_in_space_iterate(space(), blk); - blk->reset_generation(); -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/shared/cardGeneration.cpp 2015-05-12 11:56:31.917017322 +0200 @@ -0,0 +1,360 @@ +/* + * Copyright (c) 2014, 2015, 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/shared/blockOffsetTable.inline.hpp" +#include "gc/shared/cardGeneration.inline.hpp" +#include "gc/shared/gcLocker.hpp" +#include "gc/shared/genOopClosures.inline.hpp" +#include "gc/shared/genRemSet.hpp" +#include "gc/shared/generationSpec.hpp" +#include "gc/shared/space.inline.hpp" +#include "memory/iterator.hpp" +#include "memory/memRegion.hpp" +#include "runtime/java.hpp" + +CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size, + int level, + GenRemSet* remset) : + Generation(rs, initial_byte_size, level), _rs(remset), + _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(), + _used_at_prologue() +{ + HeapWord* start = (HeapWord*)rs.base(); + size_t reserved_byte_size = rs.size(); + assert((uintptr_t(start) & 3) == 0, "bad alignment"); + assert((reserved_byte_size & 3) == 0, "bad alignment"); + MemRegion reserved_mr(start, heap_word_size(reserved_byte_size)); + _bts = new BlockOffsetSharedArray(reserved_mr, + heap_word_size(initial_byte_size)); + MemRegion committed_mr(start, heap_word_size(initial_byte_size)); + _rs->resize_covered_region(committed_mr); + if (_bts == NULL) { + vm_exit_during_initialization("Could not allocate a BlockOffsetArray"); + } + + // Verify that the start and end of this generation is the start of a card. + // If this wasn't true, a single card could span more than on generation, + // which would cause problems when we commit/uncommit memory, and when we + // clear and dirty cards. + guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned"); + if (reserved_mr.end() != GenCollectedHeap::heap()->reserved_region().end()) { + // Don't check at the very end of the heap as we'll assert that we're probing off + // the end if we try. + guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned"); + } + _min_heap_delta_bytes = MinHeapDeltaBytes; + _capacity_at_prologue = initial_byte_size; + _used_at_prologue = 0; +} + +bool CardGeneration::grow_by(size_t bytes) { + assert_correct_size_change_locking(); + bool result = _virtual_space.expand_by(bytes); + if (result) { + size_t new_word_size = + heap_word_size(_virtual_space.committed_size()); + MemRegion mr(space()->bottom(), new_word_size); + // Expand card table + GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr); + // Expand shared block offset array + _bts->resize(new_word_size); + + // Fix for bug #4668531 + if (ZapUnusedHeapArea) { + MemRegion mangle_region(space()->end(), + (HeapWord*)_virtual_space.high()); + SpaceMangler::mangle_region(mangle_region); + } + + // Expand space -- also expands space's BOT + // (which uses (part of) shared array above) + space()->set_end((HeapWord*)_virtual_space.high()); + + // update the space and generation capacity counters + update_counters(); + + if (Verbose && PrintGC) { + size_t new_mem_size = _virtual_space.committed_size(); + size_t old_mem_size = new_mem_size - bytes; + gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by " + SIZE_FORMAT "K to " SIZE_FORMAT "K", + name(), old_mem_size/K, bytes/K, new_mem_size/K); + } + } + return result; +} + +bool CardGeneration::expand(size_t bytes, size_t expand_bytes) { + assert_locked_or_safepoint(Heap_lock); + if (bytes == 0) { + return true; // That's what grow_by(0) would return + } + size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes); + if (aligned_bytes == 0){ + // The alignment caused the number of bytes to wrap. An expand_by(0) will + // return true with the implication that an expansion was done when it + // was not. A call to expand implies a best effort to expand by "bytes" + // but not a guarantee. Align down to give a best effort. This is likely + // the most that the generation can expand since it has some capacity to + // start with. + aligned_bytes = ReservedSpace::page_align_size_down(bytes); + } + size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes); + bool success = false; + if (aligned_expand_bytes > aligned_bytes) { + success = grow_by(aligned_expand_bytes); + } + if (!success) { + success = grow_by(aligned_bytes); + } + if (!success) { + success = grow_to_reserved(); + } + if (PrintGC && Verbose) { + if (success && GC_locker::is_active_and_needs_gc()) { + gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead"); + } + } + + return success; +} + +bool CardGeneration::grow_to_reserved() { + assert_correct_size_change_locking(); + bool success = true; + const size_t remaining_bytes = _virtual_space.uncommitted_size(); + if (remaining_bytes > 0) { + success = grow_by(remaining_bytes); + DEBUG_ONLY(if (!success) warning("grow to reserved failed");) + } + return success; +} + +void CardGeneration::shrink(size_t bytes) { + assert_correct_size_change_locking(); + + size_t size = ReservedSpace::page_align_size_down(bytes); + if (size == 0) { + return; + } + + // Shrink committed space + _virtual_space.shrink_by(size); + // Shrink space; this also shrinks the space's BOT + space()->set_end((HeapWord*) _virtual_space.high()); + size_t new_word_size = heap_word_size(space()->capacity()); + // Shrink the shared block offset array + _bts->resize(new_word_size); + MemRegion mr(space()->bottom(), new_word_size); + // Shrink the card table + GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr); + + if (Verbose && PrintGC) { + size_t new_mem_size = _virtual_space.committed_size(); + size_t old_mem_size = new_mem_size + size; + gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", + name(), old_mem_size/K, new_mem_size/K); + } +} + +// No young generation references, clear this generation's cards. +void CardGeneration::clear_remembered_set() { + _rs->clear(reserved()); +} + +// Objects in this generation may have moved, invalidate this +// generation's cards. +void CardGeneration::invalidate_remembered_set() { + _rs->invalidate(used_region()); +} + +void CardGeneration::compute_new_size() { + assert(_shrink_factor <= 100, "invalid shrink factor"); + size_t current_shrink_factor = _shrink_factor; + _shrink_factor = 0; + + // We don't have floating point command-line arguments + // Note: argument processing ensures that MinHeapFreeRatio < 100. + const double minimum_free_percentage = MinHeapFreeRatio / 100.0; + const double maximum_used_percentage = 1.0 - minimum_free_percentage; + + // Compute some numbers about the state of the heap. + const size_t used_after_gc = used(); + const size_t capacity_after_gc = capacity(); + + const double min_tmp = used_after_gc / maximum_used_percentage; + size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx)); + // Don't shrink less than the initial generation size + minimum_desired_capacity = MAX2(minimum_desired_capacity, + spec()->init_size()); + assert(used_after_gc <= minimum_desired_capacity, "sanity check"); + + if (PrintGC && Verbose) { + const size_t free_after_gc = free(); + const double free_percentage = ((double)free_after_gc) / capacity_after_gc; + gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: "); + gclog_or_tty->print_cr(" " + " minimum_free_percentage: %6.2f" + " maximum_used_percentage: %6.2f", + minimum_free_percentage, + maximum_used_percentage); + gclog_or_tty->print_cr(" " + " free_after_gc : %6.1fK" + " used_after_gc : %6.1fK" + " capacity_after_gc : %6.1fK", + free_after_gc / (double) K, + used_after_gc / (double) K, + capacity_after_gc / (double) K); + gclog_or_tty->print_cr(" " + " free_percentage: %6.2f", + free_percentage); + } + + if (capacity_after_gc < minimum_desired_capacity) { + // If we have less free space than we want then expand + size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; + // Don't expand unless it's significant + if (expand_bytes >= _min_heap_delta_bytes) { + expand(expand_bytes, 0); // safe if expansion fails + } + if (PrintGC && Verbose) { + gclog_or_tty->print_cr(" expanding:" + " minimum_desired_capacity: %6.1fK" + " expand_bytes: %6.1fK" + " _min_heap_delta_bytes: %6.1fK", + minimum_desired_capacity / (double) K, + expand_bytes / (double) K, + _min_heap_delta_bytes / (double) K); + } + return; + } + + // No expansion, now see if we want to shrink + size_t shrink_bytes = 0; + // We would never want to shrink more than this + size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity; + + if (MaxHeapFreeRatio < 100) { + const double maximum_free_percentage = MaxHeapFreeRatio / 100.0; + const double minimum_used_percentage = 1.0 - maximum_free_percentage; + const double max_tmp = used_after_gc / minimum_used_percentage; + size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx)); + maximum_desired_capacity = MAX2(maximum_desired_capacity, + spec()->init_size()); + if (PrintGC && Verbose) { + gclog_or_tty->print_cr(" " + " maximum_free_percentage: %6.2f" + " minimum_used_percentage: %6.2f", + maximum_free_percentage, + minimum_used_percentage); + gclog_or_tty->print_cr(" " + " _capacity_at_prologue: %6.1fK" + " minimum_desired_capacity: %6.1fK" + " maximum_desired_capacity: %6.1fK", + _capacity_at_prologue / (double) K, + minimum_desired_capacity / (double) K, + maximum_desired_capacity / (double) K); + } + assert(minimum_desired_capacity <= maximum_desired_capacity, + "sanity check"); + + if (capacity_after_gc > maximum_desired_capacity) { + // Capacity too large, compute shrinking size + shrink_bytes = capacity_after_gc - maximum_desired_capacity; + // We don't want shrink all the way back to initSize if people call + // System.gc(), because some programs do that between "phases" and then + // we'd just have to grow the heap up again for the next phase. So we + // damp the shrinking: 0% on the first call, 10% on the second call, 40% + // on the third call, and 100% by the fourth call. But if we recompute + // size without shrinking, it goes back to 0%. + shrink_bytes = shrink_bytes / 100 * current_shrink_factor; + assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); + if (current_shrink_factor == 0) { + _shrink_factor = 10; + } else { + _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100); + } + if (PrintGC && Verbose) { + gclog_or_tty->print_cr(" " + " shrinking:" + " initSize: %.1fK" + " maximum_desired_capacity: %.1fK", + spec()->init_size() / (double) K, + maximum_desired_capacity / (double) K); + gclog_or_tty->print_cr(" " + " shrink_bytes: %.1fK" + " current_shrink_factor: " SIZE_FORMAT + " new shrink factor: " SIZE_FORMAT + " _min_heap_delta_bytes: %.1fK", + shrink_bytes / (double) K, + current_shrink_factor, + _shrink_factor, + _min_heap_delta_bytes / (double) K); + } + } + } + + if (capacity_after_gc > _capacity_at_prologue) { + // We might have expanded for promotions, in which case we might want to + // take back that expansion if there's room after GC. That keeps us from + // stretching the heap with promotions when there's plenty of room. + size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue; + expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes); + // We have two shrinking computations, take the largest + shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion); + assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); + if (PrintGC && Verbose) { + gclog_or_tty->print_cr(" " + " aggressive shrinking:" + " _capacity_at_prologue: %.1fK" + " capacity_after_gc: %.1fK" + " expansion_for_promotion: %.1fK" + " shrink_bytes: %.1fK", + capacity_after_gc / (double) K, + _capacity_at_prologue / (double) K, + expansion_for_promotion / (double) K, + shrink_bytes / (double) K); + } + } + // Don't shrink unless it's significant + if (shrink_bytes >= _min_heap_delta_bytes) { + shrink(shrink_bytes); + } +} + +// Currently nothing to do. +void CardGeneration::prepare_for_verify() {} + +void CardGeneration::space_iterate(SpaceClosure* blk, + bool usedOnly) { + blk->do_space(space()); +} + +void CardGeneration::younger_refs_iterate(OopsInGenClosure* blk) { + blk->set_generation(this); + younger_refs_in_space_iterate(space(), blk); + blk->reset_generation(); +}