1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/*
* 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.
*/
#include <stdio.h>
#include "garbage_collector.h"
#define ATRACE_TAG ATRACE_TAG_DALVIK
#include "cutils/trace.h"
#include "base/dumpable.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 {
Iteration::Iteration()
: duration_ns_(0), timings_("GC iteration timing logger", true, VLOG_IS_ON(heap)) {
Reset(kGcCauseBackground, false); // Reset to some place holder values.
}
void Iteration::Reset(GcCause gc_cause, bool clear_soft_references) {
timings_.Reset();
pause_times_.clear();
duration_ns_ = 0;
clear_soft_references_ = clear_soft_references;
gc_cause_ = gc_cause;
freed_ = ObjectBytePair();
freed_los_ = ObjectBytePair();
freed_bytes_revoke_ = 0;
}
uint64_t Iteration::GetEstimatedThroughput() const {
// Add 1ms to prevent possible division by 0.
return (static_cast<uint64_t>(freed_.bytes) * 1000) / (NsToMs(GetDurationNs()) + 1);
}
GarbageCollector::GarbageCollector(Heap* heap, const std::string& name)
: heap_(heap),
name_(name),
pause_histogram_((name_ + " paused").c_str(), kPauseBucketSize, kPauseBucketCount),
cumulative_timings_(name),
pause_histogram_lock_("pause histogram lock", kDefaultMutexLevel, true) {
ResetCumulativeStatistics();
}
void GarbageCollector::RegisterPause(uint64_t nano_length) {
GetCurrentIteration()->pause_times_.push_back(nano_length);
}
void GarbageCollector::ResetCumulativeStatistics() {
cumulative_timings_.Reset();
total_time_ns_ = 0;
total_freed_objects_ = 0;
total_freed_bytes_ = 0;
MutexLock mu(Thread::Current(), pause_histogram_lock_);
pause_histogram_.Reset();
}
void GarbageCollector::Run(GcCause gc_cause, bool clear_soft_references) {
ATRACE_BEGIN(StringPrintf("%s %s GC", PrettyCause(gc_cause), GetName()).c_str());
Thread* self = Thread::Current();
uint64_t start_time = NanoTime();
Iteration* current_iteration = GetCurrentIteration();
current_iteration->Reset(gc_cause, clear_soft_references);
RunPhases(); // Run all the GC phases.
// Add the current timings to the cumulative timings.
cumulative_timings_.AddLogger(*GetTimings());
// Update cumulative statistics with how many bytes the GC iteration freed.
total_freed_objects_ += current_iteration->GetFreedObjects() +
current_iteration->GetFreedLargeObjects();
total_freed_bytes_ += current_iteration->GetFreedBytes() +
current_iteration->GetFreedLargeObjectBytes();
uint64_t end_time = NanoTime();
current_iteration->SetDurationNs(end_time - start_time);
if (Locks::mutator_lock_->IsExclusiveHeld(self)) {
// The entire GC was paused, clear the fake pauses which might be in the pause times and add
// the whole GC duration.
current_iteration->pause_times_.clear();
RegisterPause(current_iteration->GetDurationNs());
}
total_time_ns_ += current_iteration->GetDurationNs();
for (uint64_t pause_time : current_iteration->GetPauseTimes()) {
MutexLock mu(self, pause_histogram_lock_);
pause_histogram_.AdjustAndAddValue(pause_time);
}
ATRACE_END();
}
void GarbageCollector::SwapBitmaps() {
TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings());
// 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 = disc_space->AsLargeObjectSpace();
accounting::LargeObjectBitmap* live_set = space->GetLiveBitmap();
accounting::LargeObjectBitmap* mark_set = space->GetMarkBitmap();
heap_->GetLiveBitmap()->ReplaceLargeObjectBitmap(live_set, mark_set);
heap_->GetMarkBitmap()->ReplaceLargeObjectBitmap(mark_set, live_set);
space->SwapBitmaps();
}
}
uint64_t GarbageCollector::GetEstimatedMeanThroughput() const {
// Add 1ms to prevent possible division by 0.
return (total_freed_bytes_ * 1000) / (NsToMs(GetCumulativeTimings().GetTotalNs()) + 1);
}
void GarbageCollector::ResetMeasurements() {
{
MutexLock mu(Thread::Current(), pause_histogram_lock_);
pause_histogram_.Reset();
}
cumulative_timings_.Reset();
total_time_ns_ = 0;
total_freed_objects_ = 0;
total_freed_bytes_ = 0;
}
GarbageCollector::ScopedPause::ScopedPause(GarbageCollector* collector)
: start_time_(NanoTime()), collector_(collector) {
Runtime::Current()->GetThreadList()->SuspendAll(__FUNCTION__);
}
GarbageCollector::ScopedPause::~ScopedPause() {
collector_->RegisterPause(NanoTime() - start_time_);
Runtime::Current()->GetThreadList()->ResumeAll();
}
// Returns the current GC iteration and assocated info.
Iteration* GarbageCollector::GetCurrentIteration() {
return heap_->GetCurrentGcIteration();
}
const Iteration* GarbageCollector::GetCurrentIteration() const {
return heap_->GetCurrentGcIteration();
}
void GarbageCollector::RecordFree(const ObjectBytePair& freed) {
GetCurrentIteration()->freed_.Add(freed);
heap_->RecordFree(freed.objects, freed.bytes);
}
void GarbageCollector::RecordFreeLOS(const ObjectBytePair& freed) {
GetCurrentIteration()->freed_los_.Add(freed);
heap_->RecordFree(freed.objects, freed.bytes);
}
uint64_t GarbageCollector::GetTotalPausedTimeNs() {
MutexLock mu(Thread::Current(), pause_histogram_lock_);
return pause_histogram_.AdjustedSum();
}
void GarbageCollector::DumpPerformanceInfo(std::ostream& os) {
const CumulativeLogger& logger = GetCumulativeTimings();
const size_t iterations = logger.GetIterations();
if (iterations == 0) {
return;
}
os << Dumpable<CumulativeLogger>(logger);
const uint64_t total_ns = logger.GetTotalNs();
double seconds = NsToMs(logger.GetTotalNs()) / 1000.0;
const uint64_t freed_bytes = GetTotalFreedBytes();
const uint64_t freed_objects = GetTotalFreedObjects();
{
MutexLock mu(Thread::Current(), pause_histogram_lock_);
if (pause_histogram_.SampleSize() > 0) {
Histogram<uint64_t>::CumulativeData cumulative_data;
pause_histogram_.CreateHistogram(&cumulative_data);
pause_histogram_.PrintConfidenceIntervals(os, 0.99, cumulative_data);
}
}
os << GetName() << " total time: " << PrettyDuration(total_ns)
<< " mean time: " << PrettyDuration(total_ns / iterations) << "\n"
<< GetName() << " freed: " << freed_objects
<< " objects with total size " << PrettySize(freed_bytes) << "\n"
<< GetName() << " throughput: " << freed_objects / seconds << "/s / "
<< PrettySize(freed_bytes / seconds) << "/s\n";
}
} // namespace collector
} // namespace gc
} // namespace art
|
