/*
* Copyright (c) 1999, 2009, 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.
*
*/
// Thread-Local Edens support
# include "incls/_precompiled.incl"
# include "incls/_threadLocalAllocBuffer.cpp.incl"
// static member initialization
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; 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();
if (PrintTLAB) {
global_stats()->print();
}
}
}
void ThreadLocalAllocBuffer::accumulate_statistics() {
size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
size_t unused = Universe::heap()->unsafe_max_tlab_alloc(myThread()) / HeapWordSize;
size_t used = capacity - unused;
// Update allocation history if a reasonable amount of eden was allocated.
bool update_allocation_history = used > 0.5 * capacity;
_gc_waste += (unsigned)remaining();
if (PrintTLAB && (_number_of_refills > 0 || Verbose)) {
print_stats("gc");
}
if (_number_of_refills > 0) {
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".
size_t allocation = _number_of_refills * desired_size();
double alloc_frac = allocation / (double) 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) {
if (end() != NULL) {
invariants();
CollectedHeap::fill_with_object(top(), hard_end(), retire);
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() {
for(JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
thread->tlab().resize();
}
}
void ThreadLocalAllocBuffer::resize() {
if (ResizeTLAB) {
// Compute the next tlab size using expected allocation amount
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);
if (PrintTLAB && Verbose) {
gclog_or_tty->print("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
" refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT "\n",
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++;
if (PrintTLAB && Verbose) {
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();
// 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();
if (PrintTLAB && Verbose) {
gclog_or_tty->print("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT "\n",
min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
}
}
size_t ThreadLocalAllocBuffer::initial_desired_size() {
size_t init_sz;
if (TLABSize > 0) {
init_sz = MIN2(TLABSize / HeapWordSize, max_size());
} else if (global_stats() == NULL) {
// Startup issue - main thread initialized before heap initialized.
init_sz = min_size();
} else {
// 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;
}
const size_t ThreadLocalAllocBuffer::max_size() {
// TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
// This restriction could be removed by enabling filling with multiple arrays.
// If we compute that the reasonable way as
// header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
// we'll overflow on the multiply, so we do the divide first.
// We actually lose a little by dividing first,
// but that just makes the TLAB somewhat smaller than the biggest array,
// which is fine, since we'll be able to fill that.
size_t unaligned_max_size = typeArrayOopDesc::header_size(T_INT) +
sizeof(jint) *
((juint) max_jint / (size_t) HeapWordSize);
return align_size_down(unaligned_max_size, MinObjAlignment);
}
void ThreadLocalAllocBuffer::print_stats(const char* tag) {
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_capacity(thrd) -
Universe::heap()->unsafe_max_tlab_alloc(thrd);
gclog_or_tty->print("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\n",
tag, 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() {
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;
gclog_or_tty->print("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\n",
_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);
}