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[zone] Get rid of the Zone's segment pool

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It's unclear that this helps performance. Let's see what the bots say.

Change-Id: Ic28783c90495f6ce01b4980d84794d394f941a4f
Reviewed-on: https://chromium-review.googlesource.com/c/1346331
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57696}
This commit is contained in:
Toon Verwaest 2018-11-21 15:44:51 +01:00 committed by Commit Bot
parent 621de4bd2c
commit 74038c86e9
7 changed files with 30 additions and 270 deletions
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8
src/api.cc
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@ -943,7 +943,6 @@ void ResourceConstraints::ConfigureDefaults(uint64_t physical_memory,
set_max_semi_space_size_in_kb(
i::Heap::ComputeMaxSemiSpaceSize(physical_memory));
set_max_old_space_size(i::Heap::ComputeMaxOldGenerationSize(physical_memory));
set_max_zone_pool_size(i::AccountingAllocator::kMaxPoolSize);
if (virtual_memory_limit > 0 && i::kRequiresCodeRange) {
// Reserve no more than 1/8 of the memory for the code range, but at most
@ -959,12 +958,10 @@ void SetResourceConstraints(i::Isolate* isolate,
size_t semi_space_size = constraints.max_semi_space_size_in_kb();
size_t old_space_size = constraints.max_old_space_size();
size_t code_range_size = constraints.code_range_size();
size_t max_pool_size = constraints.max_zone_pool_size();
if (semi_space_size != 0 || old_space_size != 0 || code_range_size != 0) {
isolate->heap()->ConfigureHeap(semi_space_size, old_space_size,
code_range_size);
}
isolate->allocator()->ConfigureSegmentPool(max_pool_size);
if (constraints.stack_limit() != nullptr) {
uintptr_t limit = reinterpret_cast<uintptr_t>(constraints.stack_limit());
@ -8460,8 +8457,8 @@ void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
isolate->wasm_engine()->allocator()->GetCurrentMemoryUsage();
heap_statistics->external_memory_ = isolate->heap()->external_memory();
heap_statistics->peak_malloced_memory_ =
isolate->allocator()->GetMaxMemoryUsage() +
isolate->wasm_engine()->allocator()->GetMaxMemoryUsage();
isolate->allocator()->GetPeakMemoryUsage() +
isolate->wasm_engine()->allocator()->GetPeakMemoryUsage();
heap_statistics->number_of_native_contexts_ = heap->NumberOfNativeContexts();
heap_statistics->number_of_detached_contexts_ =
heap->NumberOfDetachedContexts();
@ -8750,7 +8747,6 @@ void Isolate::MemoryPressureNotification(MemoryPressureLevel level) {
? isolate->thread_manager()->IsLockedByCurrentThread()
: i::ThreadId::Current().Equals(isolate->thread_id());
isolate->heap()->MemoryPressureNotification(level, on_isolate_thread);
isolate->allocator()->MemoryPressureNotification(level);
}
void Isolate::EnableMemorySavingsMode() {

2
src/heap/heap.cc
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@ -4040,7 +4040,7 @@ void Heap::RecordStats(HeapStats* stats, bool take_snapshot) {
memory_allocator()->Size() + memory_allocator()->Available();
*stats->os_error = base::OS::GetLastError();
*stats->malloced_memory = isolate_->allocator()->GetCurrentMemoryUsage();
*stats->malloced_peak_memory = isolate_->allocator()->GetMaxMemoryUsage();
*stats->malloced_peak_memory = isolate_->allocator()->GetPeakMemoryUsage();
if (take_snapshot) {
HeapIterator iterator(this);
for (HeapObject* obj = iterator.next(); obj != nullptr;

36
src/isolate.cc
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@ -2641,26 +2641,20 @@ void Isolate::ThreadDataTable::RemoveAllThreads() {
class VerboseAccountingAllocator : public AccountingAllocator {
public:
VerboseAccountingAllocator(Heap* heap, size_t allocation_sample_bytes,
size_t pool_sample_bytes)
VerboseAccountingAllocator(Heap* heap, size_t allocation_sample_bytes)
: heap_(heap),
last_memory_usage_(0),
last_pool_size_(0),
nesting_deepth_(0),
allocation_sample_bytes_(allocation_sample_bytes),
pool_sample_bytes_(pool_sample_bytes) {}
allocation_sample_bytes_(allocation_sample_bytes) {}
v8::internal::Segment* GetSegment(size_t size) override {
v8::internal::Segment* memory = AccountingAllocator::GetSegment(size);
if (memory) {
size_t malloced_current = GetCurrentMemoryUsage();
size_t pooled_current = GetCurrentPoolSize();
if (last_memory_usage_ + allocation_sample_bytes_ < malloced_current ||
last_pool_size_ + pool_sample_bytes_ < pooled_current) {
PrintMemoryJSON(malloced_current, pooled_current);
if (last_memory_usage_ + allocation_sample_bytes_ < malloced_current) {
PrintMemoryJSON(malloced_current);
last_memory_usage_ = malloced_current;
last_pool_size_ = pooled_current;
}
}
return memory;
@ -2669,13 +2663,10 @@ class VerboseAccountingAllocator : public AccountingAllocator {
void ReturnSegment(v8::internal::Segment* memory) override {
AccountingAllocator::ReturnSegment(memory);
size_t malloced_current = GetCurrentMemoryUsage();
size_t pooled_current = GetCurrentPoolSize();
if (malloced_current + allocation_sample_bytes_ < last_memory_usage_ ||
pooled_current + pool_sample_bytes_ < last_pool_size_) {
PrintMemoryJSON(malloced_current, pooled_current);
if (malloced_current + allocation_sample_bytes_ < last_memory_usage_) {
PrintMemoryJSON(malloced_current);
last_memory_usage_ = malloced_current;
last_pool_size_ = pooled_current;
}
}
@ -2707,7 +2698,7 @@ class VerboseAccountingAllocator : public AccountingAllocator {
zone->allocation_size(), nesting_deepth_.load());
}
void PrintMemoryJSON(size_t malloced, size_t pooled) {
void PrintMemoryJSON(size_t malloced) {
// Note: Neither isolate, nor heap is locked, so be careful with accesses
// as the allocator is potentially used on a concurrent thread.
double time = heap_->isolate()->time_millis_since_init();
@ -2716,17 +2707,14 @@ class VerboseAccountingAllocator : public AccountingAllocator {
"\"type\": \"zone\", "
"\"isolate\": \"%p\", "
"\"time\": %f, "
"\"allocated\": %" PRIuS
","
"\"pooled\": %" PRIuS "}\n",
reinterpret_cast<void*>(heap_->isolate()), time, malloced, pooled);
"\"allocated\": %" PRIuS "}\n",
reinterpret_cast<void*>(heap_->isolate()), time, malloced);
}
Heap* heap_;
std::atomic<size_t> last_memory_usage_;
std::atomic<size_t> last_pool_size_;
std::atomic<size_t> nesting_deepth_;
size_t allocation_sample_bytes_, pool_sample_bytes_;
size_t allocation_sample_bytes_;
};
#ifdef DEBUG
@ -2794,8 +2782,8 @@ Isolate::Isolate(std::unique_ptr<i::IsolateAllocator> isolate_allocator)
: isolate_allocator_(std::move(isolate_allocator)),
id_(base::Relaxed_AtomicIncrement(&isolate_counter_, 1)),
stack_guard_(this),
allocator_(FLAG_trace_zone_stats ? new VerboseAccountingAllocator(
&heap_, 256 * KB, 128 * KB)
allocator_(FLAG_trace_zone_stats
? new VerboseAccountingAllocator(&heap_, 256 * KB)
: new AccountingAllocator()),
builtins_(this),
rail_mode_(PERFORMANCE_ANIMATION),

167
src/zone/accounting-allocator.cc
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@ -15,71 +15,9 @@
namespace v8 {
namespace internal {
AccountingAllocator::AccountingAllocator() : unused_segments_mutex_() {
static const size_t kDefaultBucketMaxSize = 5;
memory_pressure_level_.SetValue(MemoryPressureLevel::kNone);
std::fill(unused_segments_heads_, unused_segments_heads_ + kNumberBuckets,
nullptr);
std::fill(unused_segments_sizes_, unused_segments_sizes_ + kNumberBuckets, 0);
std::fill(unused_segments_max_sizes_,
unused_segments_max_sizes_ + kNumberBuckets, kDefaultBucketMaxSize);
}
AccountingAllocator::~AccountingAllocator() { ClearPool(); }
void AccountingAllocator::MemoryPressureNotification(
MemoryPressureLevel level) {
memory_pressure_level_.SetValue(level);
if (level != MemoryPressureLevel::kNone) {
ClearPool();
}
}
void AccountingAllocator::ConfigureSegmentPool(const size_t max_pool_size) {
// The sum of the bytes of one segment of each size.
static const size_t full_size = (size_t(1) << (kMaxSegmentSizePower + 1)) -
(size_t(1) << kMinSegmentSizePower);
size_t fits_fully = max_pool_size / full_size;
base::MutexGuard lock_guard(&unused_segments_mutex_);
// We assume few zones (less than 'fits_fully' many) to be active at the same
// time. When zones grow regularly, they will keep requesting segments of
// increasing size each time. Therefore we try to get as many segments with an
// equal number of segments of each size as possible.
// The remaining space is used to make more room for an 'incomplete set' of
// segments beginning with the smaller ones.
// This code will work best if the max_pool_size is a multiple of the
// full_size. If max_pool_size is no sum of segment sizes the actual pool
// size might be smaller then max_pool_size. Note that no actual memory gets
// wasted though.
// TODO(heimbuef): Determine better strategy generating a segment sizes
// distribution that is closer to real/benchmark usecases and uses the given
// max_pool_size more efficiently.
size_t total_size = fits_fully * full_size;
for (size_t power = 0; power < kNumberBuckets; ++power) {
if (total_size + (size_t(1) << (power + kMinSegmentSizePower)) <=
max_pool_size) {
unused_segments_max_sizes_[power] = fits_fully + 1;
total_size += size_t(1) << power;
} else {
unused_segments_max_sizes_[power] = fits_fully;
}
}
}
Segment* AccountingAllocator::GetSegment(size_t bytes) {
Segment* result = GetSegmentFromPool(bytes);
if (result == nullptr) {
result = AllocateSegment(bytes);
if (result != nullptr) {
result->Initialize(bytes);
}
}
Segment* result = AllocateSegment(bytes);
if (result != nullptr) result->Initialize(bytes);
return result;
}
@ -88,9 +26,9 @@ Segment* AccountingAllocator::AllocateSegment(size_t bytes) {
if (memory != nullptr) {
base::AtomicWord current =
base::Relaxed_AtomicIncrement(&current_memory_usage_, bytes);
base::AtomicWord max = base::Relaxed_Load(&max_memory_usage_);
while (current > max) {
max = base::Relaxed_CompareAndSwap(&max_memory_usage_, max, current);
base::AtomicWord peak = base::Relaxed_Load(&peak_memory_usage_);
while (current > peak) {
peak = base::Relaxed_CompareAndSwap(&peak_memory_usage_, peak, current);
}
}
return reinterpret_cast<Segment*>(memory);
@ -98,12 +36,7 @@ Segment* AccountingAllocator::AllocateSegment(size_t bytes) {
void AccountingAllocator::ReturnSegment(Segment* segment) {
segment->ZapContents();
if (memory_pressure_level_.Value() != MemoryPressureLevel::kNone) {
FreeSegment(segment);
} else if (!AddSegmentToPool(segment)) {
FreeSegment(segment);
}
}
void AccountingAllocator::FreeSegment(Segment* memory) {
@ -113,95 +46,13 @@ void AccountingAllocator::FreeSegment(Segment* memory) {
free(memory);
}
size_t AccountingAllocator::GetPeakMemoryUsage() const {
return base::Relaxed_Load(&peak_memory_usage_);
}
size_t AccountingAllocator::GetCurrentMemoryUsage() const {
return base::Relaxed_Load(&current_memory_usage_);
}
size_t AccountingAllocator::GetMaxMemoryUsage() const {
return base::Relaxed_Load(&max_memory_usage_);
}
size_t AccountingAllocator::GetCurrentPoolSize() const {
return base::Relaxed_Load(&current_pool_size_);
}
Segment* AccountingAllocator::GetSegmentFromPool(size_t requested_size) {
if (requested_size > (1 << kMaxSegmentSizePower)) {
return nullptr;
}
size_t power = kMinSegmentSizePower;
while (requested_size > (static_cast<size_t>(1) << power)) power++;
DCHECK_GE(power, kMinSegmentSizePower + 0);
power -= kMinSegmentSizePower;
Segment* segment;
{
base::MutexGuard lock_guard(&unused_segments_mutex_);
segment = unused_segments_heads_[power];
if (segment != nullptr) {
unused_segments_heads_[power] = segment->next();
segment->set_next(nullptr);
unused_segments_sizes_[power]--;
base::Relaxed_AtomicIncrement(
&current_pool_size_, -static_cast<base::AtomicWord>(segment->size()));
}
}
if (segment) {
DCHECK_GE(segment->size(), requested_size);
}
return segment;
}
bool AccountingAllocator::AddSegmentToPool(Segment* segment) {
size_t size = segment->size();
if (size >= (1 << (kMaxSegmentSizePower + 1))) return false;
if (size < (1 << kMinSegmentSizePower)) return false;
size_t power = kMaxSegmentSizePower;
while (size < (static_cast<size_t>(1) << power)) power--;
DCHECK_GE(power, kMinSegmentSizePower + 0);
power -= kMinSegmentSizePower;
{
base::MutexGuard lock_guard(&unused_segments_mutex_);
if (unused_segments_sizes_[power] >= unused_segments_max_sizes_[power]) {
return false;
}
segment->set_next(unused_segments_heads_[power]);
unused_segments_heads_[power] = segment;
base::Relaxed_AtomicIncrement(&current_pool_size_, size);
unused_segments_sizes_[power]++;
}
return true;
}
void AccountingAllocator::ClearPool() {
base::MutexGuard lock_guard(&unused_segments_mutex_);
for (size_t power = 0; power <= kMaxSegmentSizePower - kMinSegmentSizePower;
power++) {
Segment* current = unused_segments_heads_[power];
while (current) {
Segment* next = current->next();
FreeSegment(current);
current = next;
}
unused_segments_heads_[power] = nullptr;
}
}
} // namespace internal
} // namespace v8

50
src/zone/accounting-allocator.h
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@ -21,67 +21,25 @@ namespace internal {
class V8_EXPORT_PRIVATE AccountingAllocator {
public:
static const size_t kMaxPoolSize = 8ul * KB;
AccountingAllocator() {}
virtual ~AccountingAllocator() {}
AccountingAllocator();
virtual ~AccountingAllocator();
// Gets an empty segment from the pool or creates a new one.
virtual Segment* GetSegment(size_t bytes);
// Return unneeded segments to either insert them into the pool or release
// them if the pool is already full or memory pressure is high.
virtual void ReturnSegment(Segment* memory);
size_t GetPeakMemoryUsage() const;
size_t GetCurrentMemoryUsage() const;
size_t GetMaxMemoryUsage() const;
size_t GetCurrentPoolSize() const;
void MemoryPressureNotification(MemoryPressureLevel level);
// Configures the zone segment pool size limits so the pool does not
// grow bigger than max_pool_size.
// TODO(heimbuef): Do not accept segments to pool that are larger than
// their size class requires. Sometimes the zones generate weird segments.
void ConfigureSegmentPool(const size_t max_pool_size);
virtual void ZoneCreation(const Zone* zone) {}
virtual void ZoneDestruction(const Zone* zone) {}
private:
FRIEND_TEST(Zone, SegmentPoolConstraints);
static const size_t kMinSegmentSizePower = 13;
static const size_t kMaxSegmentSizePower = 18;
STATIC_ASSERT(kMinSegmentSizePower <= kMaxSegmentSizePower);
static const size_t kNumberBuckets =
1 + kMaxSegmentSizePower - kMinSegmentSizePower;
// Allocates a new segment. Returns nullptr on failed allocation.
Segment* AllocateSegment(size_t bytes);
void FreeSegment(Segment* memory);
// Returns a segment from the pool of at least the requested size.
Segment* GetSegmentFromPool(size_t requested_size);
// Trys to add a segment to the pool. Returns false if the pool is full.
bool AddSegmentToPool(Segment* segment);
// Empties the pool and puts all its contents onto the garbage stack.
void ClearPool();
Segment* unused_segments_heads_[kNumberBuckets];
size_t unused_segments_sizes_[kNumberBuckets];
size_t unused_segments_max_sizes_[kNumberBuckets];
base::Mutex unused_segments_mutex_;
base::AtomicWord peak_memory_usage_ = 0;
base::AtomicWord current_memory_usage_ = 0;
base::AtomicWord max_memory_usage_ = 0;
base::AtomicWord current_pool_size_ = 0;
base::AtomicValue<MemoryPressureLevel> memory_pressure_level_;
DISALLOW_COPY_AND_ASSIGN(AccountingAllocator);
};

1
test/unittests/BUILD.gn
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@ -212,7 +212,6 @@ v8_source_set("unittests_sources") {
"wasm/wasm-macro-gen-unittest.cc",
"wasm/wasm-module-builder-unittest.cc",
"wasm/wasm-opcodes-unittest.cc",
"zone/segmentpool-unittest.cc",
"zone/zone-allocator-unittest.cc",
"zone/zone-chunk-list-unittest.cc",
"zone/zone-unittest.cc",

32
test/unittests/zone/segmentpool-unittest.cc
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@ -1,32 +0,0 @@
// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/zone/accounting-allocator.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace v8 {
namespace internal {
TEST(Zone, SegmentPoolConstraints) {
size_t sizes[]{
0, // Corner case
AccountingAllocator::kMaxPoolSize,
GB // Something really large
};
AccountingAllocator allocator;
for (size_t size : sizes) {
allocator.ConfigureSegmentPool(size);
size_t total_size = 0;
for (size_t power = 0; power < AccountingAllocator::kNumberBuckets;
++power) {
total_size +=
allocator.unused_segments_max_sizes_[power] * (size_t(1) << power);
}
EXPECT_LE(total_size, size);
}
}
} // namespace internal
} // namespace v8