Method Free

paddle/phi/core/memory/allocation/buddy_allocator.cc:147–218

}

void BuddyAllocator::Free(void* p) {
  // Point back to metadata
  auto block = static_cast<MemoryBlock*>(p)->Metadata();
#ifdef PADDLE_WITH_CUSTOM_DEVICE
  if (use_custom_device_) {
    block = static_cast<MemoryBlock*>(p);
  }
#endif
  // Acquire the allocator lock
  std::lock_guard<std::mutex> lock(mutex_);

  VLOG(10) << "Free from address " << block;

  auto* desc = cache_.LoadDesc(block);
  if (desc->get_type() == MemoryBlock::HUGE_CHUNK) {
    VLOG(10) << "Free directly from system allocator";
    system_allocator_->Free(block, desc->get_total_size(), desc->get_index());

    // Invalidate GPU allocation from cache
    cache_.Invalidate(block);

    return;
  }

  block->MarkAsFree(&cache_);

  total_used_ -= desc->get_total_size();
  total_free_ += desc->get_total_size();

  // Trying to merge the right buddy
  MemoryBlock* right_buddy = block->GetRightBuddy(&cache_);
  if (right_buddy) {
    VLOG(10) << "Merging this block " << block << " with its right buddy "
             << right_buddy;

    auto rb_desc = cache_.LoadDesc(right_buddy);
    if (rb_desc->get_type() == MemoryBlock::FREE_CHUNK) {
      // Take away right buddy from pool
      pool_.erase(IndexSizeAddress(
          rb_desc->get_index(), rb_desc->get_total_size(), right_buddy));

      // merge its right buddy to the block
      block->Merge(&cache_, right_buddy);
    }
  }

  // Trying to merge the left buddy
  MemoryBlock* left_buddy = block->GetLeftBuddy(&cache_);
  if (left_buddy) {
    VLOG(10) << "Merging this block " << block << " with its left buddy "
             << left_buddy;

    // auto left_buddy = block->left_buddy(cache_);
    auto* lb_desc = cache_.LoadDesc(left_buddy);
    if (lb_desc->get_type() == MemoryBlock::FREE_CHUNK) {
      // Take away right buddy from pool
      pool_.erase(IndexSizeAddress(
          lb_desc->get_index(), lb_desc->get_total_size(), left_buddy));