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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define ATRACE_TAG ATRACE_TAG_DALVIK
#include <stdio.h>
#include <cutils/trace.h>
#include "garbage_collector.h"
#include "base/histogram-inl.h"
#include "base/logging.h"
#include "base/mutex-inl.h"
#include "gc/accounting/heap_bitmap.h"
#include "gc/space/large_object_space.h"
#include "gc/space/space-inl.h"
#include "thread-inl.h"
#include "thread_list.h"
namespace art {
namespace gc {
namespace collector {
GarbageCollector::GarbageCollector(Heap* heap, const std::string& name)
: heap_(heap),
name_(name),
gc_cause_(kGcCauseForAlloc),
clear_soft_references_(false),
duration_ns_(0),
timings_(name_.c_str(), true, VLOG_IS_ON(heap)),
pause_histogram_((name_ + " paused").c_str(), kPauseBucketSize, kPauseBucketCount),
cumulative_timings_(name) {
ResetCumulativeStatistics();
}
void GarbageCollector::PausePhase() {
}
void GarbageCollector::RegisterPause(uint64_t nano_length) {
pause_times_.push_back(nano_length);
}
void GarbageCollector::ResetCumulativeStatistics() {
cumulative_timings_.Reset();
pause_histogram_.Reset();
total_time_ns_ = 0;
total_freed_objects_ = 0;
total_freed_bytes_ = 0;
}
void GarbageCollector::Run(GcCause gc_cause, bool clear_soft_references) {
ThreadList* thread_list = Runtime::Current()->GetThreadList();
Thread* self = Thread::Current();
uint64_t start_time = NanoTime();
pause_times_.clear();
duration_ns_ = 0;
clear_soft_references_ = clear_soft_references;
gc_cause_ = gc_cause;
// Reset stats.
freed_bytes_ = 0;
freed_large_object_bytes_ = 0;
freed_objects_ = 0;
freed_large_objects_ = 0;
CollectorType collector_type = GetCollectorType();
switch (collector_type) {
case kCollectorTypeMS: // Fall through.
case kCollectorTypeSS: // Fall through.
case kCollectorTypeGSS: {
InitializePhase();
// Pause is the entire length of the GC.
uint64_t pause_start = NanoTime();
ATRACE_BEGIN("Application threads suspended");
// Mutator lock may be already exclusively held when we do garbage collections for changing
// the current collector / allocator during process state updates.
if (Locks::mutator_lock_->IsExclusiveHeld(self)) {
// PreGcRosAllocVerification() is called in Heap::TransitionCollector().
RevokeAllThreadLocalBuffers();
MarkingPhase();
PausePhase();
ReclaimPhase();
// PostGcRosAllocVerification() is called in Heap::TransitionCollector().
} else {
ATRACE_BEGIN("Suspending mutator threads");
thread_list->SuspendAll();
ATRACE_END();
GetHeap()->PreGcRosAllocVerification(&timings_);
RevokeAllThreadLocalBuffers();
MarkingPhase();
PausePhase();
ReclaimPhase();
GetHeap()->PostGcRosAllocVerification(&timings_);
ATRACE_BEGIN("Resuming mutator threads");
thread_list->ResumeAll();
ATRACE_END();
}
ATRACE_END();
RegisterPause(NanoTime() - pause_start);
FinishPhase();
break;
}
case kCollectorTypeCMS: {
InitializePhase();
CHECK(!Locks::mutator_lock_->IsExclusiveHeld(self));
{
ReaderMutexLock mu(self, *Locks::mutator_lock_);
MarkingPhase();
}
uint64_t pause_start = NanoTime();
ATRACE_BEGIN("Suspending mutator threads");
thread_list->SuspendAll();
ATRACE_END();
ATRACE_BEGIN("All mutator threads suspended");
GetHeap()->PreGcRosAllocVerification(&timings_);
PausePhase();
RevokeAllThreadLocalBuffers();
GetHeap()->PostGcRosAllocVerification(&timings_);
ATRACE_END();
uint64_t pause_end = NanoTime();
ATRACE_BEGIN("Resuming mutator threads");
thread_list->ResumeAll();
ATRACE_END();
RegisterPause(pause_end - pause_start);
{
ReaderMutexLock mu(self, *Locks::mutator_lock_);
ReclaimPhase();
}
FinishPhase();
break;
}
case kCollectorTypeCC: {
// To be implemented.
break;
}
default: {
LOG(FATAL) << "Unreachable collector type=" << static_cast<size_t>(collector_type);
break;
}
}
// Add the current timings to the cumulative timings.
cumulative_timings_.AddLogger(timings_);
// Update cumulative statistics with how many bytes the GC iteration freed.
total_freed_objects_ += GetFreedObjects() + GetFreedLargeObjects();
total_freed_bytes_ += GetFreedBytes() + GetFreedLargeObjectBytes();
uint64_t end_time = NanoTime();
duration_ns_ = end_time - start_time;
total_time_ns_ += GetDurationNs();
for (uint64_t pause_time : pause_times_) {
pause_histogram_.AddValue(pause_time / 1000);
}
}
void GarbageCollector::SwapBitmaps() {
// Swap the live and mark bitmaps for each alloc space. This is needed since sweep re-swaps
// these bitmaps. The bitmap swapping is an optimization so that we do not need to clear the live
// bits of dead objects in the live bitmap.
const GcType gc_type = GetGcType();
for (const auto& space : GetHeap()->GetContinuousSpaces()) {
// We never allocate into zygote spaces.
if (space->GetGcRetentionPolicy() == space::kGcRetentionPolicyAlwaysCollect ||
(gc_type == kGcTypeFull &&
space->GetGcRetentionPolicy() == space::kGcRetentionPolicyFullCollect)) {
accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap();
accounting::ContinuousSpaceBitmap* mark_bitmap = space->GetMarkBitmap();
if (live_bitmap != nullptr && live_bitmap != mark_bitmap) {
heap_->GetLiveBitmap()->ReplaceBitmap(live_bitmap, mark_bitmap);
heap_->GetMarkBitmap()->ReplaceBitmap(mark_bitmap, live_bitmap);
CHECK(space->IsContinuousMemMapAllocSpace());
space->AsContinuousMemMapAllocSpace()->SwapBitmaps();
}
}
}
for (const auto& disc_space : GetHeap()->GetDiscontinuousSpaces()) {
space::LargeObjectSpace* space = down_cast<space::LargeObjectSpace*>(disc_space);
accounting::ObjectSet* live_set = space->GetLiveObjects();
accounting::ObjectSet* mark_set = space->GetMarkObjects();
heap_->GetLiveBitmap()->ReplaceObjectSet(live_set, mark_set);
heap_->GetMarkBitmap()->ReplaceObjectSet(mark_set, live_set);
down_cast<space::LargeObjectSpace*>(space)->SwapBitmaps();
}
}
uint64_t GarbageCollector::GetEstimatedMeanThroughput() const {
// Add 1ms to prevent possible division by 0.
return (total_freed_bytes_ * 1000) / (NsToMs(GetCumulativeTimings().GetTotalNs()) + 1);
}
uint64_t GarbageCollector::GetEstimatedLastIterationThroughput() const {
// Add 1ms to prevent possible division by 0.
return (static_cast<uint64_t>(freed_bytes_) * 1000) / (NsToMs(GetDurationNs()) + 1);
}
void GarbageCollector::ResetMeasurements() {
cumulative_timings_.Reset();
pause_histogram_.Reset();
total_time_ns_ = 0;
total_freed_objects_ = 0;
total_freed_bytes_ = 0;
}
} // namespace collector
} // namespace gc
} // namespace art
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