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[handles] Return node blocks for traced handles

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Return empty node blocks back to the OS. Keep one block around to
support local allocation/deallocation patterns for up to 256 nodes.

Bug: v8:13372
Change-Id: Ib9e3a1b9a70fa4ad2b52e8479cc46e3c7316cd18
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3973270
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84011}
This commit is contained in:
Michael Lippautz 2022-10-26 11:54:18 +02:00 committed by V8 LUCI CQ
parent c0dba826d8
commit 7caf58b5fd
1 changed files with 45 additions and 4 deletions
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49
src/handles/traced-handles.cc
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@ -22,6 +22,8 @@ namespace {
class TracedNodeBlock;
// TODO(v8:13372): Avoid constant and instead make use of
// `v8::base::AllocateAtLeast()` to maximize utilization of the memory.
constexpr size_t kBlockSize = 256;
constexpr uint16_t kInvalidFreeListNodeIndex = -1;
@ -207,6 +209,8 @@ class DoublyLinkedList final {
T* Front() { return front_; }
void PushFront(T* object) {
DCHECK(!Contains(object));
ListNodeFor(object)->next = front_;
if (front_) {
ListNodeFor(front_)->prev = object;
@ -334,6 +338,7 @@ class TracedNodeBlock final {
Iterator end() { return Iterator(this, kBlockSize); }
bool IsFull() const { return used_ == kBlockSize; }
bool IsEmpty() const { return used_ == 0; }
private:
TracedNode nodes_[kBlockSize];
@ -431,7 +436,8 @@ class TracedHandlesImpl final {
size_t used_node_count() const { return used_; }
size_t total_size_bytes() const {
return sizeof(TracedNode) * kBlockSize * blocks_.Size();
return sizeof(TracedNode) * kBlockSize *
(blocks_.Size() + empty_blocks_.size());
}
size_t used_size_bytes() const { return sizeof(TracedNode) * used_; }
@ -448,6 +454,7 @@ class TracedHandlesImpl final {
TracedNodeBlock::OverallList blocks_;
TracedNodeBlock::UsableList usable_blocks_;
std::vector<TracedNode*> young_nodes_;
std::vector<TracedNodeBlock*> empty_blocks_;
Isolate* isolate_;
bool is_marking_ = false;
bool is_sweeping_on_mutator_thread_ = false;
@ -457,7 +464,15 @@ class TracedHandlesImpl final {
TracedNode* TracedHandlesImpl::AllocateNode() {
auto* block = usable_blocks_.Front();
if (!block) {
block = new TracedNodeBlock(*this, blocks_, usable_blocks_);
if (empty_blocks_.empty()) {
block = new TracedNodeBlock(*this, blocks_, usable_blocks_);
} else {
block = empty_blocks_.back();
empty_blocks_.pop_back();
DCHECK(block->IsEmpty());
usable_blocks_.PushFront(block);
blocks_.PushFront(block);
}
DCHECK_EQ(block, usable_blocks_.Front());
}
auto* node = block->AllocateNode();
@ -472,12 +487,16 @@ TracedNode* TracedHandlesImpl::AllocateNode() {
void TracedHandlesImpl::FreeNode(TracedNode* node) {
auto& block = node->GetNodeBlock();
// TODO(v8:13372): Keep vector of empty blocks that could be freed after
// fixing up young nodes.
if (block.IsFull() && !usable_blocks_.Contains(&block)) {
usable_blocks_.PushFront(&block);
}
block.FreeNode(node);
if (block.IsEmpty()) {
DCHECK(usable_blocks_.Contains(&block));
usable_blocks_.Remove(&block);
blocks_.Remove(&block);
empty_blocks_.push_back(&block);
}
used_--;
}
@ -489,6 +508,9 @@ TracedHandlesImpl::~TracedHandlesImpl() {
blocks_.PopFront();
delete block;
}
for (auto* block : empty_blocks_) {
delete block;
}
}
Handle<Object> TracedHandlesImpl::Create(Address value, Address* slot,
@ -606,6 +628,23 @@ const TracedHandles::NodeBounds TracedHandlesImpl::GetNodeBounds() const {
return block_bounds;
}
namespace {
void DeleteEmptyBlocks(std::vector<TracedNodeBlock*>& empty_blocks) {
// Keep one node block around for fast allocation/deallocation patterns.
if (empty_blocks.size() <= 1) return;
for (size_t i = 1; i < empty_blocks.size(); i++) {
auto* block = empty_blocks[i];
DCHECK(block->IsEmpty());
delete block;
}
empty_blocks.resize(1);
empty_blocks.shrink_to_fit();
}
} // namespace
void TracedHandlesImpl::UpdateListOfYoungNodes() {
size_t last = 0;
for (auto* node : young_nodes_) {
@ -623,6 +662,7 @@ void TracedHandlesImpl::UpdateListOfYoungNodes() {
DCHECK_LE(last, young_nodes_.size());
young_nodes_.resize(last);
young_nodes_.shrink_to_fit();
DeleteEmptyBlocks(empty_blocks_);
}
void TracedHandlesImpl::ClearListOfYoungNodes() {
@ -633,6 +673,7 @@ void TracedHandlesImpl::ClearListOfYoungNodes() {
}
young_nodes_.clear();
young_nodes_.shrink_to_fit();
DeleteEmptyBlocks(empty_blocks_);
}
void TracedHandlesImpl::ResetDeadNodes(