/* * Copyright (c) 2001, 2010, 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_implementation/parNew/parGCAllocBuffer.hpp" #include "gc_implementation/shared/collectorCounters.hpp" #include "memory/allocation.inline.hpp" #include "memory/blockOffsetTable.inline.hpp" #include "memory/generation.inline.hpp" #include "memory/generationSpec.hpp" #include "memory/space.hpp" #include "memory/tenuredGeneration.hpp" #include "oops/oop.inline.hpp" #include "runtime/java.hpp" TenuredGeneration::TenuredGeneration(ReservedSpace rs, size_t initial_byte_size, int level, GenRemSet* remset) : OneContigSpaceCardGeneration(rs, initial_byte_size, MinHeapDeltaBytes, level, remset, NULL) { HeapWord* bottom = (HeapWord*) _virtual_space.low(); HeapWord* end = (HeapWord*) _virtual_space.high(); _the_space = new TenuredSpace(_bts, MemRegion(bottom, end)); _the_space->reset_saved_mark(); _shrink_factor = 0; _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, &_virtual_space); _gc_counters = new CollectorCounters("MSC", 1); _space_counters = new CSpaceCounters(gen_name, 0, _virtual_space.reserved_size(), _the_space, _gen_counters); #ifndef SERIALGC if (UseParNewGC && ParallelGCThreads > 0) { typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr; _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr, ParallelGCThreads); if (_alloc_buffers == NULL) vm_exit_during_initialization("Could not allocate alloc_buffers"); for (uint i = 0; i < ParallelGCThreads; i++) { _alloc_buffers[i] = new ParGCAllocBufferWithBOT(OldPLABSize, _bts); if (_alloc_buffers[i] == NULL) vm_exit_during_initialization("Could not allocate alloc_buffers"); } } else { _alloc_buffers = NULL; } #endif // SERIALGC } const char* TenuredGeneration::name() const { return "tenured generation"; } void TenuredGeneration::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: %d" " new shrink factor: %d" " _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); } assert(used() == used_after_gc && used_after_gc <= capacity(), "sanity check"); } void TenuredGeneration::gc_prologue(bool full) { _capacity_at_prologue = capacity(); _used_at_prologue = used(); if (VerifyBeforeGC) { verify_alloc_buffers_clean(); } } void TenuredGeneration::gc_epilogue(bool full) { if (VerifyAfterGC) { verify_alloc_buffers_clean(); } OneContigSpaceCardGeneration::gc_epilogue(full); } 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. bool result = false; if (!result && full) { result = true; if (PrintGC && Verbose) { gclog_or_tty->print_cr("TenuredGeneration::should_collect: because" " full"); } } if (!result && should_allocate(size, is_tlab)) { result = true; if (PrintGC && Verbose) { gclog_or_tty->print_cr("TenuredGeneration::should_collect: because" " should_allocate(" SIZE_FORMAT ")", size); } } // If we don't have very much free space. // XXX: 10000 should be a percentage of the capacity!!! if (!result && free() < 10000) { result = true; if (PrintGC && Verbose) { gclog_or_tty->print_cr("TenuredGeneration::should_collect: because" " free(): " SIZE_FORMAT, free()); } } // If we had to expand to accomodate promotions from younger generations if (!result && _capacity_at_prologue < capacity()) { result = true; if (PrintGC && Verbose) { gclog_or_tty->print_cr("TenuredGeneration::should_collect: because" "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT, _capacity_at_prologue, capacity()); } } return result; } void TenuredGeneration::collect(bool full, bool clear_all_soft_refs, size_t size, bool is_tlab) { retire_alloc_buffers_before_full_gc(); OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs, size, is_tlab); } void TenuredGeneration::update_gc_stats(int current_level, bool full) { // If the next lower level(s) has been collected, gather any statistics // that are of interest at this point. if (!full && (current_level + 1) == level()) { // Calculate size of data promoted from the younger generations // before doing the collection. size_t used_before_gc = used(); // If the younger gen collections were 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(); } } #ifndef SERIALGC oop TenuredGeneration::par_promote(int thread_num, oop old, markOop m, size_t word_sz) { ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num]; HeapWord* obj_ptr = buf->allocate(word_sz); bool is_lab = true; if (obj_ptr == NULL) { #ifndef PRODUCT if (Universe::heap()->promotion_should_fail()) { return NULL; } #endif // #ifndef PRODUCT // Slow path: if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) { // Is small enough; abandon this buffer and start a new one. size_t buf_size = buf->word_sz(); HeapWord* buf_space = TenuredGeneration::par_allocate(buf_size, false); if (buf_space == NULL) { buf_space = expand_and_allocate(buf_size, false, true /* parallel*/); } if (buf_space != NULL) { buf->retire(false, false); buf->set_buf(buf_space); obj_ptr = buf->allocate(word_sz); assert(obj_ptr != NULL, "Buffer was definitely big enough..."); } }; // Otherwise, buffer allocation failed; try allocating object // individually. if (obj_ptr == NULL) { obj_ptr = TenuredGeneration::par_allocate(word_sz, false); if (obj_ptr == NULL) { obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */); } } if (obj_ptr == NULL) return NULL; } assert(obj_ptr != NULL, "program logic"); Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz); oop obj = oop(obj_ptr); // Restore the mark word copied above. obj->set_mark(m); return obj; } void TenuredGeneration::par_promote_alloc_undo(int thread_num, HeapWord* obj, size_t word_sz) { ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num]; if (buf->contains(obj)) { guarantee(buf->contains(obj + word_sz - 1), "should contain whole object"); buf->undo_allocation(obj, word_sz); } else { CollectedHeap::fill_with_object(obj, word_sz); } } void TenuredGeneration::par_promote_alloc_done(int thread_num) { ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num]; buf->retire(true, ParallelGCRetainPLAB); } void TenuredGeneration::retire_alloc_buffers_before_full_gc() { if (UseParNewGC) { for (uint i = 0; i < ParallelGCThreads; i++) { _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/); } } } // Verify that any retained parallel allocation buffers do not // intersect with dirty cards. void TenuredGeneration::verify_alloc_buffers_clean() { if (UseParNewGC) { for (uint i = 0; i < ParallelGCThreads; i++) { _rs->verify_aligned_region_empty(_alloc_buffers[i]->range()); } } } #else // SERIALGC void TenuredGeneration::retire_alloc_buffers_before_full_gc() {} void TenuredGeneration::verify_alloc_buffers_clean() {} #endif // SERIALGC bool TenuredGeneration::promotion_attempt_is_safe( size_t max_promotion_in_bytes, bool younger_handles_promotion_failure) const { bool result = max_contiguous_available() >= max_promotion_in_bytes; if (younger_handles_promotion_failure && !result) { result = max_contiguous_available() >= (size_t) gc_stats()->avg_promoted()->padded_average(); if (PrintGC && Verbose && result) { gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe" " contiguous_available: " SIZE_FORMAT " avg_promoted: " SIZE_FORMAT, max_contiguous_available(), gc_stats()->avg_promoted()->padded_average()); } } else { if (PrintGC && Verbose) { gclog_or_tty->print_cr("TenuredGeneration::promotion_attempt_is_safe" " contiguous_available: " SIZE_FORMAT " promotion_in_bytes: " SIZE_FORMAT, max_contiguous_available(), max_promotion_in_bytes); } } return result; }