diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp Tue Sep 12 19:03:39 2017 +0200 @@ -0,0 +1,436 @@ +/* + * Copyright (c) 1999, 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/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/thread.inline.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 +} + +void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() { + global_stats()->initialize(); + + for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->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 (end() != NULL) { + invariants(); + + if (retire) { + myThread()->incr_allocated_bytes(used_bytes()); + } + + CollectedHeap::fill_with_object(top(), hard_end(), retire && zap); + + if (retire || ZeroTLAB) { // "Reset" the TLAB + set_start(NULL); + set_top(NULL); + set_pf_top(NULL); + set_end(NULL); + } + } + assert(!(retire || ZeroTLAB) || + (start() == NULL && end() == NULL && top() == NULL), + "TLAB must be reset"); +} + +void ThreadLocalAllocBuffer::resize_all_tlabs() { + if (ResizeTLAB) { + for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->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"); + initialize(start, top, start + new_size - alignment_reserve()); + + // 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_end(end); + invariants(); +} + +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 (primordial) + // 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 (primordial) 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 = alloc == 0 ? 0.0 : + 100.0 * 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"); +} + +Thread* ThreadLocalAllocBuffer::myThread() { + return (Thread*)(((char *)this) + + in_bytes(start_offset()) - + in_bytes(Thread::tlab_start_offset())); +} + + +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 = _total_allocation == 0 ? 0.0 : + 100.0 * 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); +}