/* * Copyright (c) 1999, 2017, 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/genCollectedHeap.hpp" #include "gc/shared/threadLocalAllocBuffer.inline.hpp" #include "logging/log.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.inline.hpp" #include "oops/oop.inline.hpp" #include "runtime/heapMonitoring.hpp" #include "runtime/thread.inline.hpp" #include "runtime/threadSMR.hpp" #include "utilities/copy.hpp" // Thread-Local Edens support // static member initialization size_t ThreadLocalAllocBuffer::_max_size = 0; int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0; unsigned ThreadLocalAllocBuffer::_target_refills = 0; GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL; void ThreadLocalAllocBuffer::clear_before_allocation() { _slow_refill_waste += (unsigned)remaining(); make_parsable(true); // also retire the TLAB } size_t ThreadLocalAllocBuffer::remaining() { if (current_end() == NULL) { return 0; } // TODO: To be deprecated when FastTLABRefill is deprecated. update_end_pointers(); return pointer_delta(reserved_end(), top()); } void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() { global_stats()->initialize(); for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { thread->tlab().accumulate_statistics(); thread->tlab().initialize_statistics(); } // Publish new stats if some allocation occurred. if (global_stats()->allocation() != 0) { global_stats()->publish(); global_stats()->print(); } } void ThreadLocalAllocBuffer::accumulate_statistics() { Thread* thread = myThread(); size_t capacity = Universe::heap()->tlab_capacity(thread); size_t used = Universe::heap()->tlab_used(thread); _gc_waste += (unsigned)remaining(); size_t total_allocated = thread->allocated_bytes(); size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc; _allocated_before_last_gc = total_allocated; print_stats("gc"); if (_number_of_refills > 0) { // Update allocation history if a reasonable amount of eden was allocated. bool update_allocation_history = used > 0.5 * capacity; if (update_allocation_history) { // Average the fraction of eden allocated in a tlab by this // thread for use in the next resize operation. // _gc_waste is not subtracted because it's included in // "used". // The result can be larger than 1.0 due to direct to old allocations. // These allocations should ideally not be counted but since it is not possible // to filter them out here we just cap the fraction to be at most 1.0. double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used); _allocation_fraction.sample(alloc_frac); } global_stats()->update_allocating_threads(); global_stats()->update_number_of_refills(_number_of_refills); global_stats()->update_allocation(_number_of_refills * desired_size()); global_stats()->update_gc_waste(_gc_waste); global_stats()->update_slow_refill_waste(_slow_refill_waste); global_stats()->update_fast_refill_waste(_fast_refill_waste); } else { assert(_number_of_refills == 0 && _fast_refill_waste == 0 && _slow_refill_waste == 0 && _gc_waste == 0, "tlab stats == 0"); } global_stats()->update_slow_allocations(_slow_allocations); } // Fills the current tlab with a dummy filler array to create // an illusion of a contiguous Eden and optionally retires the tlab. // Waste accounting should be done in caller as appropriate; see, // for example, clear_before_allocation(). void ThreadLocalAllocBuffer::make_parsable(bool retire, bool zap) { if (current_end() != NULL) { invariants(); if (retire) { myThread()->incr_allocated_bytes(used_bytes()); } // TODO: To be deprecated when FastTLABRefill is deprecated. update_end_pointers(); CollectedHeap::fill_with_object(top(), reserved_end(), retire && zap); if (retire || ZeroTLAB) { // "Reset" the TLAB set_start(NULL); set_top(NULL); set_pf_top(NULL); set_current_end(NULL); set_allocation_end(NULL); set_last_slow_path_end(NULL); } } assert(!(retire || ZeroTLAB) || (start() == NULL && current_end() == NULL && top() == NULL && _allocation_end == NULL && _last_slow_path_end == NULL), "TLAB must be reset"); } void ThreadLocalAllocBuffer::resize_all_tlabs() { if (ResizeTLAB) { for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { thread->tlab().resize(); } } } void ThreadLocalAllocBuffer::resize() { // Compute the next tlab size using expected allocation amount assert(ResizeTLAB, "Should not call this otherwise"); size_t alloc = (size_t)(_allocation_fraction.average() * (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize)); size_t new_size = alloc / _target_refills; new_size = MIN2(MAX2(new_size, min_size()), max_size()); size_t aligned_new_size = align_object_size(new_size); log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]" " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT, p2i(myThread()), myThread()->osthread()->thread_id(), _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size); set_desired_size(aligned_new_size); set_refill_waste_limit(initial_refill_waste_limit()); } void ThreadLocalAllocBuffer::initialize_statistics() { _number_of_refills = 0; _fast_refill_waste = 0; _slow_refill_waste = 0; _gc_waste = 0; _slow_allocations = 0; } void ThreadLocalAllocBuffer::fill(HeapWord* start, HeapWord* top, size_t new_size) { _number_of_refills++; print_stats("fill"); assert(top <= start + new_size - alignment_reserve(), "size too small"); // Remember old bytes until sample for the next tlab only if this is our first // actual refill. size_t old_bytes_until_sample = 0; if (_number_of_refills > 1) { old_bytes_until_sample = _bytes_until_sample; } initialize(start, top, start + new_size - alignment_reserve()); if (old_bytes_until_sample > 0) { set_bytes_until_sample(old_bytes_until_sample); set_sample_end(); } // Reset amount of internal fragmentation set_refill_waste_limit(initial_refill_waste_limit()); } void ThreadLocalAllocBuffer::initialize(HeapWord* start, HeapWord* top, HeapWord* end) { set_start(start); set_top(top); set_pf_top(top); set_current_end(end); set_allocation_end(end); set_last_slow_path_end(end); invariants(); _bytes_until_sample = 0; } void ThreadLocalAllocBuffer::initialize() { initialize(NULL, // start NULL, // top NULL); // end set_desired_size(initial_desired_size()); // Following check is needed because at startup the main // thread is initialized before the heap is. The initialization for // this thread is redone in startup_initialization below. if (Universe::heap() != NULL) { size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize; double alloc_frac = desired_size() * target_refills() / (double) capacity; _allocation_fraction.sample(alloc_frac); } set_refill_waste_limit(initial_refill_waste_limit()); initialize_statistics(); } void ThreadLocalAllocBuffer::startup_initialization() { // Assuming each thread's active tlab is, on average, // 1/2 full at a GC _target_refills = 100 / (2 * TLABWasteTargetPercent); _target_refills = MAX2(_target_refills, (unsigned)1U); _global_stats = new GlobalTLABStats(); #ifdef COMPILER2 // If the C2 compiler is present, extra space is needed at the end of // TLABs, otherwise prefetching instructions generated by the C2 // compiler will fault (due to accessing memory outside of heap). // The amount of space is the max of the number of lines to // prefetch for array and for instance allocations. (Extra space must be // reserved to accommodate both types of allocations.) // // Only SPARC-specific BIS instructions are known to fault. (Those // instructions are generated if AllocatePrefetchStyle==3 and // AllocatePrefetchInstr==1). To be on the safe side, however, // extra space is reserved for all combinations of // AllocatePrefetchStyle and AllocatePrefetchInstr. // // If the C2 compiler is not present, no space is reserved. // +1 for rounding up to next cache line, +1 to be safe if (is_server_compilation_mode_vm()) { int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2; _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) / (int)HeapWordSize; } #endif // During jvm startup, the main thread is initialized // before the heap is initialized. So reinitialize it now. guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread"); Thread::current()->tlab().initialize(); log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT, min_size(), Thread::current()->tlab().initial_desired_size(), max_size()); } size_t ThreadLocalAllocBuffer::initial_desired_size() { size_t init_sz = 0; if (TLABSize > 0) { init_sz = TLABSize / HeapWordSize; } else if (global_stats() != NULL) { // Initial size is a function of the average number of allocating threads. unsigned nof_threads = global_stats()->allocating_threads_avg(); init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) / (nof_threads * target_refills()); init_sz = align_object_size(init_sz); } init_sz = MIN2(MAX2(init_sz, min_size()), max_size()); return init_sz; } void ThreadLocalAllocBuffer::print_stats(const char* tag) { Log(gc, tlab) log; if (!log.is_trace()) { return; } Thread* thrd = myThread(); size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste; size_t alloc = _number_of_refills * _desired_size; double waste_percent = percent_of(waste, alloc); size_t tlab_used = Universe::heap()->tlab_used(thrd); log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]" " desired_size: " SIZE_FORMAT "KB" " slow allocs: %d refill waste: " SIZE_FORMAT "B" " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB" " slow: %dB fast: %dB", tag, p2i(thrd), thrd->osthread()->thread_id(), _desired_size / (K / HeapWordSize), _slow_allocations, _refill_waste_limit * HeapWordSize, _allocation_fraction.average(), _allocation_fraction.average() * tlab_used / K, _number_of_refills, waste_percent, _gc_waste * HeapWordSize, _slow_refill_waste * HeapWordSize, _fast_refill_waste * HeapWordSize); } void ThreadLocalAllocBuffer::verify() { HeapWord* p = start(); HeapWord* t = top(); HeapWord* prev_p = NULL; while (p < t) { oop(p)->verify(); prev_p = p; p += oop(p)->size(); } guarantee(p == top(), "end of last object must match end of space"); } void ThreadLocalAllocBuffer::set_sample_end() { size_t heap_words_remaining = pointer_delta(_current_end, _top); size_t bytes_left = _bytes_until_sample; size_t words_until_sample = bytes_left / HeapWordSize; if (heap_words_remaining > words_until_sample) { HeapWord* new_end = _top + words_until_sample; set_current_end(new_end); set_last_slow_path_end(new_end); set_bytes_until_sample(0); } else { bytes_left -= heap_words_remaining * HeapWordSize; set_bytes_until_sample(bytes_left); } } void ThreadLocalAllocBuffer::pick_next_sample(size_t overflowed_words) { if (!HeapMonitoring::enabled()) { return; } if (_bytes_until_sample == 0) { HeapMonitoring::pick_next_sample(&_bytes_until_sample); } if (overflowed_words > 0) { // Try to correct sample size by removing extra space from last allocation. if (_bytes_until_sample > overflowed_words * HeapWordSize) { set_bytes_until_sample(_bytes_until_sample - overflowed_words * HeapWordSize); } } set_sample_end(); log_trace(gc, tlab)("TLAB picked next sample: thread: " INTPTR_FORMAT " [id: %2d]" " start: " INTPTR_FORMAT " top: " INTPTR_FORMAT " end: " INTPTR_FORMAT " allocation_end:" INTPTR_FORMAT " last_slow_path_end: " INTPTR_FORMAT, p2i(myThread()), myThread()->osthread()->thread_id(), p2i(start()), p2i(top()), p2i(current_end()), p2i(_allocation_end), p2i(_last_slow_path_end)); } Thread* ThreadLocalAllocBuffer::myThread() { return (Thread*)(((char *)this) + in_bytes(start_offset()) - in_bytes(Thread::tlab_start_offset())); } void ThreadLocalAllocBuffer::set_back_allocation_end() { // Did a fast TLAB refill occur? if (_last_slow_path_end != _current_end) { // Fix up the actual end to be now the end of this TLAB. _last_slow_path_end = _current_end; _allocation_end = _current_end; } else { _current_end = _allocation_end; } } void ThreadLocalAllocBuffer::handle_sample(Thread* thread, HeapWord* result, size_t size_in_bytes) { if (!HeapMonitoring::enabled()) { return; } if (_bytes_until_sample < size_in_bytes) { HeapMonitoring::object_alloc_do_sample(thread, reinterpret_cast(result), size_in_bytes); } update_tlab_sample_point(size_in_bytes); } void ThreadLocalAllocBuffer::update_tlab_sample_point(size_t size_in_bytes) { if (_bytes_until_sample > size_in_bytes) { _bytes_until_sample -= size_in_bytes; return; } // We sampled here, so reset it all and start a new sample point. set_bytes_until_sample(0); set_back_allocation_end(); pick_next_sample(); } void ThreadLocalAllocBuffer::update_end_pointers() { // Did a fast TLAB refill occur? (This will be deprecated when fast TLAB // refill disappears). if (_last_slow_path_end != _current_end) { // Fix up the last slow path end to be now the end of this TLAB. _last_slow_path_end = _current_end; _allocation_end = _current_end; } } HeapWord* ThreadLocalAllocBuffer::reserved_end() { assert (_last_slow_path_end == _current_end, "Have to call update_end_pointers before reserved_end."); return _allocation_end + alignment_reserve(); } GlobalTLABStats::GlobalTLABStats() : _allocating_threads_avg(TLABAllocationWeight) { initialize(); _allocating_threads_avg.sample(1); // One allocating thread at startup if (UsePerfData) { EXCEPTION_MARK; ResourceMark rm; char* cname = PerfDataManager::counter_name("tlab", "allocThreads"); _perf_allocating_threads = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); cname = PerfDataManager::counter_name("tlab", "fills"); _perf_total_refills = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); cname = PerfDataManager::counter_name("tlab", "maxFills"); _perf_max_refills = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); cname = PerfDataManager::counter_name("tlab", "alloc"); _perf_allocation = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "gcWaste"); _perf_gc_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "maxGcWaste"); _perf_max_gc_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "slowWaste"); _perf_slow_refill_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "maxSlowWaste"); _perf_max_slow_refill_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "fastWaste"); _perf_fast_refill_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "maxFastWaste"); _perf_max_fast_refill_waste = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); cname = PerfDataManager::counter_name("tlab", "slowAlloc"); _perf_slow_allocations = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc"); _perf_max_slow_allocations = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); } } void GlobalTLABStats::initialize() { // Clear counters summarizing info from all threads _allocating_threads = 0; _total_refills = 0; _max_refills = 0; _total_allocation = 0; _total_gc_waste = 0; _max_gc_waste = 0; _total_slow_refill_waste = 0; _max_slow_refill_waste = 0; _total_fast_refill_waste = 0; _max_fast_refill_waste = 0; _total_slow_allocations = 0; _max_slow_allocations = 0; } void GlobalTLABStats::publish() { _allocating_threads_avg.sample(_allocating_threads); if (UsePerfData) { _perf_allocating_threads ->set_value(_allocating_threads); _perf_total_refills ->set_value(_total_refills); _perf_max_refills ->set_value(_max_refills); _perf_allocation ->set_value(_total_allocation); _perf_gc_waste ->set_value(_total_gc_waste); _perf_max_gc_waste ->set_value(_max_gc_waste); _perf_slow_refill_waste ->set_value(_total_slow_refill_waste); _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste); _perf_fast_refill_waste ->set_value(_total_fast_refill_waste); _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste); _perf_slow_allocations ->set_value(_total_slow_allocations); _perf_max_slow_allocations ->set_value(_max_slow_allocations); } } void GlobalTLABStats::print() { Log(gc, tlab) log; if (!log.is_debug()) { return; } size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste; double waste_percent = percent_of(waste, _total_allocation); log.debug("TLAB totals: thrds: %d refills: %d max: %d" " slow allocs: %d max %d waste: %4.1f%%" " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B", _allocating_threads, _total_refills, _max_refills, _total_slow_allocations, _max_slow_allocations, waste_percent, _total_gc_waste * HeapWordSize, _max_gc_waste * HeapWordSize, _total_slow_refill_waste * HeapWordSize, _max_slow_refill_waste * HeapWordSize, _total_fast_refill_waste * HeapWordSize, _max_fast_refill_waste * HeapWordSize); }