| /* |
| * Copyright (c) 2001, 2022, 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/serial/cardTableRS.hpp" |
| #include "gc/serial/genMarkSweep.hpp" |
| #include "gc/serial/serialBlockOffsetTable.inline.hpp" |
| #include "gc/serial/tenuredGeneration.inline.hpp" |
| #include "gc/shared/collectorCounters.hpp" |
| #include "gc/shared/gcLocker.hpp" |
| #include "gc/shared/gcTimer.hpp" |
| #include "gc/shared/gcTrace.hpp" |
| #include "gc/shared/genCollectedHeap.hpp" |
| #include "gc/shared/generationSpec.hpp" |
| #include "gc/shared/space.hpp" |
| #include "logging/log.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/java.hpp" |
| #include "utilities/macros.hpp" |
| |
| bool TenuredGeneration::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()->rem_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(); |
| |
| size_t new_mem_size = _virtual_space.committed_size(); |
| size_t old_mem_size = new_mem_size - bytes; |
| log_trace(gc, heap)("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 TenuredGeneration::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 (success && GCLocker::is_active_and_needs_gc()) { |
| log_trace(gc, heap)("Garbage collection disabled, expanded heap instead"); |
| } |
| |
| return success; |
| } |
| |
| bool TenuredGeneration::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) log_warning(gc)("grow to reserved failed");) |
| } |
| return success; |
| } |
| |
| void TenuredGeneration::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()->rem_set()->resize_covered_region(mr); |
| |
| size_t new_mem_size = _virtual_space.committed_size(); |
| size_t old_mem_size = new_mem_size + size; |
| log_trace(gc, heap)("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K", |
| name(), old_mem_size/K, new_mem_size/K); |
| } |
| |
| // Objects in this generation may have moved, invalidate this |
| // generation's cards. |
| void TenuredGeneration::invalidate_remembered_set() { |
| _rs->invalidate(used_region()); |
| } |
| |
| void TenuredGeneration::compute_new_size_inner() { |
| assert(_shrink_factor <= 100, "invalid shrink factor"); |
| size_t current_shrink_factor = _shrink_factor; |
| if (ShrinkHeapInSteps) { |
| // Always reset '_shrink_factor' if the heap is shrunk in steps. |
| // If we shrink the heap in this iteration, '_shrink_factor' will |
| // be recomputed based on the old value further down in this function. |
| _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, initial_size()); |
| assert(used_after_gc <= minimum_desired_capacity, "sanity check"); |
| |
| const size_t free_after_gc = free(); |
| const double free_percentage = ((double)free_after_gc) / capacity_after_gc; |
| log_trace(gc, heap)("TenuredGeneration::compute_new_size:"); |
| log_trace(gc, heap)(" minimum_free_percentage: %6.2f maximum_used_percentage: %6.2f", |
| minimum_free_percentage, |
| maximum_used_percentage); |
| log_trace(gc, heap)(" 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); |
| log_trace(gc, heap)(" 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 |
| } |
| log_trace(gc, heap)(" 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, initial_size()); |
| log_trace(gc, heap)(" maximum_free_percentage: %6.2f minimum_used_percentage: %6.2f", |
| maximum_free_percentage, minimum_used_percentage); |
| log_trace(gc, heap)(" _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; |
| if (ShrinkHeapInSteps) { |
| // If ShrinkHeapInSteps is true (the default), |
| // we don't want to 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; |
| if (current_shrink_factor == 0) { |
| _shrink_factor = 10; |
| } else { |
| _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100); |
| } |
| } |
| assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size"); |
| log_trace(gc, heap)(" shrinking: initSize: %.1fK maximum_desired_capacity: %.1fK", |
| initial_size() / (double) K, maximum_desired_capacity / (double) K); |
| log_trace(gc, heap)(" 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"); |
| log_trace(gc, heap)(" 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); |
| } |
| } |
| |
| void TenuredGeneration::space_iterate(SpaceClosure* blk, |
| bool usedOnly) { |
| blk->do_space(space()); |
| } |
| |
| void TenuredGeneration::younger_refs_iterate(OopIterateClosure* blk) { |
| // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in |
| // "sp" that point into the young generation. |
| // The iteration is only over objects allocated at the start of the |
| // iterations; objects allocated as a result of applying the closure are |
| // not included. |
| |
| _rs->younger_refs_in_space_iterate(space(), blk); |
| } |
| |
| TenuredGeneration::TenuredGeneration(ReservedSpace rs, |
| size_t initial_byte_size, |
| size_t min_byte_size, |
| size_t max_byte_size, |
| CardTableRS* remset) : |
| Generation(rs, initial_byte_size), _rs(remset), |
| _min_heap_delta_bytes(), _capacity_at_prologue(), |
| _used_at_prologue() |
| { |
| // If we don't shrink the heap in steps, '_shrink_factor' is always 100%. |
| _shrink_factor = ShrinkHeapInSteps ? 0 : 100; |
| 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); |
| |
| // 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; |
| HeapWord* bottom = (HeapWord*) _virtual_space.low(); |
| HeapWord* end = (HeapWord*) _virtual_space.high(); |
| _the_space = new TenuredSpace(_bts, MemRegion(bottom, end)); |
| // If we don't shrink the heap in steps, '_shrink_factor' is always 100%. |
| _shrink_factor = ShrinkHeapInSteps ? 0 : 100; |
| _capacity_at_prologue = 0; |
| |
| _gc_stats = new GCStats(); |
| |
| // initialize performance counters |
| |
| const char* gen_name = "old"; |
| // Generation Counters -- generation 1, 1 subspace |
| _gen_counters = new GenerationCounters(gen_name, 1, 1, |
| min_byte_size, max_byte_size, &_virtual_space); |
| |
| _gc_counters = new CollectorCounters("Serial full collection pauses", 1); |
| |
| _space_counters = new CSpaceCounters(gen_name, 0, |
| _virtual_space.reserved_size(), |
| _the_space, _gen_counters); |
| } |
| |
| void TenuredGeneration::gc_prologue(bool full) { |
| _capacity_at_prologue = capacity(); |
| _used_at_prologue = used(); |
| } |
| |
| bool TenuredGeneration::should_collect(bool full, |
| size_t size, |
| bool is_tlab) { |
| // This should be one big conditional or (||), but I want to be able to tell |
| // why it returns what it returns (without re-evaluating the conditionals |
| // in case they aren't idempotent), so I'm doing it this way. |
| // DeMorgan says it's okay. |
| if (full) { |
| log_trace(gc)("TenuredGeneration::should_collect: because full"); |
| return true; |
| } |
| if (should_allocate(size, is_tlab)) { |
| log_trace(gc)("TenuredGeneration::should_collect: because should_allocate(" SIZE_FORMAT ")", size); |
| return true; |
| } |
| // If we don't have very much free space. |
| // XXX: 10000 should be a percentage of the capacity!!! |
| if (free() < 10000) { |
| log_trace(gc)("TenuredGeneration::should_collect: because free(): " SIZE_FORMAT, free()); |
| return true; |
| } |
| // If we had to expand to accommodate promotions from the young generation |
| if (_capacity_at_prologue < capacity()) { |
| log_trace(gc)("TenuredGeneration::should_collect: because_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT, |
| _capacity_at_prologue, capacity()); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| void TenuredGeneration::compute_new_size() { |
| assert_locked_or_safepoint(Heap_lock); |
| |
| // Compute some numbers about the state of the heap. |
| const size_t used_after_gc = used(); |
| const size_t capacity_after_gc = capacity(); |
| |
| compute_new_size_inner(); |
| |
| assert(used() == used_after_gc && used_after_gc <= capacity(), |
| "used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT |
| " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()); |
| } |
| |
| void TenuredGeneration::update_gc_stats(Generation* current_generation, |
| bool full) { |
| // If the young generation has been collected, gather any statistics |
| // that are of interest at this point. |
| bool current_is_young = GenCollectedHeap::heap()->is_young_gen(current_generation); |
| if (!full && current_is_young) { |
| // Calculate size of data promoted from the young generation |
| // before doing the collection. |
| size_t used_before_gc = used(); |
| |
| // If the young gen collection was skipped, then the |
| // number of promoted bytes will be 0 and adding it to the |
| // average will incorrectly lessen the average. It is, however, |
| // also possible that no promotion was needed. |
| if (used_before_gc >= _used_at_prologue) { |
| size_t promoted_in_bytes = used_before_gc - _used_at_prologue; |
| gc_stats()->avg_promoted()->sample(promoted_in_bytes); |
| } |
| } |
| } |
| |
| void TenuredGeneration::update_counters() { |
| if (UsePerfData) { |
| _space_counters->update_all(); |
| _gen_counters->update_all(); |
| } |
| } |
| |
| bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { |
| size_t available = max_contiguous_available(); |
| size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); |
| bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); |
| |
| log_trace(gc)("Tenured: promo attempt is%s safe: available(" SIZE_FORMAT ") %s av_promo(" SIZE_FORMAT "), max_promo(" SIZE_FORMAT ")", |
| res? "":" not", available, res? ">=":"<", av_promo, max_promotion_in_bytes); |
| |
| return res; |
| } |
| |
| void TenuredGeneration::collect(bool full, |
| bool clear_all_soft_refs, |
| size_t size, |
| bool is_tlab) { |
| GenCollectedHeap* gch = GenCollectedHeap::heap(); |
| |
| STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); |
| gc_timer->register_gc_start(); |
| |
| SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); |
| gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); |
| |
| gch->pre_full_gc_dump(gc_timer); |
| |
| GenMarkSweep::invoke_at_safepoint(clear_all_soft_refs); |
| |
| gch->post_full_gc_dump(gc_timer); |
| |
| gc_timer->register_gc_end(); |
| |
| gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); |
| } |
| |
| HeapWord* |
| TenuredGeneration::expand_and_allocate(size_t word_size, bool is_tlab) { |
| assert(!is_tlab, "TenuredGeneration does not support TLAB allocation"); |
| expand(word_size*HeapWordSize, _min_heap_delta_bytes); |
| return _the_space->allocate(word_size); |
| } |
| |
| size_t TenuredGeneration::unsafe_max_alloc_nogc() const { |
| return _the_space->free(); |
| } |
| |
| size_t TenuredGeneration::contiguous_available() const { |
| return _the_space->free() + _virtual_space.uncommitted_size(); |
| } |
| |
| void TenuredGeneration::assert_correct_size_change_locking() { |
| assert_locked_or_safepoint(Heap_lock); |
| } |
| |
| void TenuredGeneration::object_iterate(ObjectClosure* blk) { |
| _the_space->object_iterate(blk); |
| } |
| |
| void TenuredGeneration::complete_loaded_archive_space(MemRegion archive_space) { |
| // Create the BOT for the archive space. |
| TenuredSpace* space = _the_space; |
| space->initialize_threshold(); |
| HeapWord* start = archive_space.start(); |
| while (start < archive_space.end()) { |
| size_t word_size = _the_space->block_size(start); |
| space->alloc_block(start, start + word_size); |
| start += word_size; |
| } |
| } |
| |
| void TenuredGeneration::save_marks() { |
| _the_space->set_saved_mark(); |
| } |
| |
| bool TenuredGeneration::no_allocs_since_save_marks() { |
| return _the_space->saved_mark_at_top(); |
| } |
| |
| void TenuredGeneration::gc_epilogue(bool full) { |
| // update the generation and space performance counters |
| update_counters(); |
| if (ZapUnusedHeapArea) { |
| _the_space->check_mangled_unused_area_complete(); |
| } |
| } |
| |
| void TenuredGeneration::record_spaces_top() { |
| assert(ZapUnusedHeapArea, "Not mangling unused space"); |
| _the_space->set_top_for_allocations(); |
| } |
| |
| void TenuredGeneration::verify() { |
| _the_space->verify(); |
| } |
| |
| void TenuredGeneration::print_on(outputStream* st) const { |
| Generation::print_on(st); |
| st->print(" the"); |
| _the_space->print_on(st); |
| } |
