diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/memory/tenuredGeneration.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/hotspot/src/share/vm/memory/tenuredGeneration.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,446 @@ +/* + * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +# include "incls/_precompiled.incl" +# include "incls/_tenuredGeneration.cpp.incl" + +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 { + SharedHeap::fill_region_with_object(MemRegion(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_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; +}