コード例 #1
0
/**
 * 计算当前线程的本地分配缓冲区的新大小
 */
inline size_t ThreadLocalAllocBuffer::compute_size(size_t obj_size) {
  const size_t aligned_obj_size = align_object_size(obj_size);

  // Compute the size for the new TLAB.
  // The "last" tlab may be smaller to reduce fragmentation.
  // unsafe_max_tlab_alloc is just a hint.
  const size_t available_size = Universe::heap()->unsafe_max_tlab_alloc(myThread()) / HeapWordSize;
  size_t new_tlab_size = MIN2(available_size, desired_size() + aligned_obj_size);

  // Make sure there's enough room for object and filler int[].
  const size_t obj_plus_filler_size = aligned_obj_size + alignment_reserve();
  if (new_tlab_size < obj_plus_filler_size) {
    // If there isn't enough room for the allocation, return failure.
    if (PrintTLAB && Verbose) {
      gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
                    " returns failure",
                    obj_size);
    }
    return 0;
  }

  if (PrintTLAB && Verbose) {
    gclog_or_tty->print_cr("ThreadLocalAllocBuffer::compute_size(" SIZE_FORMAT ")"
                  " returns " SIZE_FORMAT,
                  obj_size, new_tlab_size);
  }
  return new_tlab_size;
}
コード例 #2
0
/**
 * 根据统计信息调整当前线程的本地分配缓冲区的基准大小
 */
void ThreadLocalAllocBuffer::resize() {

  if (ResizeTLAB) {	//允许调整线程的本地分配缓冲区大小
    // 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;

    //根据本地分配缓冲区大小允许的最大值/最小值来调整缓冲区的新大小
    new_size = MIN2(MAX2(new_size, min_size()), max_size());

    //内存对齐后的大小
    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());
  }
}
コード例 #3
0
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);
}
コード例 #4
0
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;

  if (PrintTLAB && (_number_of_refills > 0 || Verbose)) {
    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);
}
コード例 #5
0
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);

  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",
                        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());
}
コード例 #6
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 (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();
}
コード例 #7
0
 size_t initial_refill_waste_limit()            { return desired_size() / TLABRefillWasteFraction; }