1 // Copyright 2015 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "src/heap/memory-reducer.h"
6
7 #include "src/flags/flags.h"
8 #include "src/heap/gc-tracer.h"
9 #include "src/heap/heap-inl.h"
10 #include "src/heap/incremental-marking.h"
11 #include "src/init/v8.h"
12 #include "src/utils/utils.h"
13
14 namespace v8 {
15 namespace internal {
16
17 const int MemoryReducer::kLongDelayMs = 8000;
18 const int MemoryReducer::kShortDelayMs = 500;
19 const int MemoryReducer::kWatchdogDelayMs = 100000;
20 const int MemoryReducer::kMaxNumberOfGCs = 3;
21 const double MemoryReducer::kCommittedMemoryFactor = 1.1;
22 const size_t MemoryReducer::kCommittedMemoryDelta = 10 * MB;
23
MemoryReducer(Heap * heap)24 MemoryReducer::MemoryReducer(Heap* heap)
25 : heap_(heap),
26 taskrunner_(V8::GetCurrentPlatform()->GetForegroundTaskRunner(
27 reinterpret_cast<v8::Isolate*>(heap->isolate()))),
28 state_(kDone, 0, 0.0, 0.0, 0),
29 js_calls_counter_(0),
30 js_calls_sample_time_ms_(0.0) {}
31
TimerTask(MemoryReducer * memory_reducer)32 MemoryReducer::TimerTask::TimerTask(MemoryReducer* memory_reducer)
33 : CancelableTask(memory_reducer->heap()->isolate()),
34 memory_reducer_(memory_reducer) {}
35
36
RunInternal()37 void MemoryReducer::TimerTask::RunInternal() {
38 Heap* heap = memory_reducer_->heap();
39 Event event;
40 double time_ms = heap->MonotonicallyIncreasingTimeInMs();
41 heap->tracer()->SampleAllocation(time_ms, heap->NewSpaceAllocationCounter(),
42 heap->OldGenerationAllocationCounter(),
43 heap->EmbedderAllocationCounter());
44 bool low_allocation_rate = heap->HasLowAllocationRate();
45 bool optimize_for_memory = heap->ShouldOptimizeForMemoryUsage();
46 if (FLAG_trace_gc_verbose) {
47 heap->isolate()->PrintWithTimestamp(
48 "Memory reducer: %s, %s\n",
49 low_allocation_rate ? "low alloc" : "high alloc",
50 optimize_for_memory ? "background" : "foreground");
51 }
52 event.type = kTimer;
53 event.time_ms = time_ms;
54 // The memory reducer will start incremental markig if
55 // 1) mutator is likely idle: js call rate is low and allocation rate is low.
56 // 2) mutator is in background: optimize for memory flag is set.
57 event.should_start_incremental_gc =
58 low_allocation_rate || optimize_for_memory;
59 event.can_start_incremental_gc =
60 heap->incremental_marking()->IsStopped() &&
61 (heap->incremental_marking()->CanBeActivated() || optimize_for_memory);
62 event.committed_memory = heap->CommittedOldGenerationMemory();
63 memory_reducer_->NotifyTimer(event);
64 }
65
66
NotifyTimer(const Event & event)67 void MemoryReducer::NotifyTimer(const Event& event) {
68 DCHECK_EQ(kTimer, event.type);
69 DCHECK_EQ(kWait, state_.action);
70 state_ = Step(state_, event);
71 if (state_.action == kRun) {
72 DCHECK(heap()->incremental_marking()->IsStopped());
73 DCHECK(FLAG_incremental_marking);
74 if (FLAG_trace_gc_verbose) {
75 heap()->isolate()->PrintWithTimestamp("Memory reducer: started GC #%d\n",
76 state_.started_gcs);
77 }
78 heap()->StartIdleIncrementalMarking(
79 GarbageCollectionReason::kMemoryReducer,
80 kGCCallbackFlagCollectAllExternalMemory);
81 } else if (state_.action == kWait) {
82 if (!heap()->incremental_marking()->IsStopped() &&
83 heap()->ShouldOptimizeForMemoryUsage()) {
84 // Make progress with pending incremental marking if memory usage has
85 // higher priority than latency. This is important for background tabs
86 // that do not send idle notifications.
87 const int kIncrementalMarkingDelayMs = 500;
88 double deadline = heap()->MonotonicallyIncreasingTimeInMs() +
89 kIncrementalMarkingDelayMs;
90 heap()->incremental_marking()->AdvanceWithDeadline(
91 deadline, IncrementalMarking::NO_GC_VIA_STACK_GUARD,
92 StepOrigin::kTask);
93 heap()->FinalizeIncrementalMarkingIfComplete(
94 GarbageCollectionReason::kFinalizeMarkingViaTask);
95 }
96 // Re-schedule the timer.
97 ScheduleTimer(state_.next_gc_start_ms - event.time_ms);
98 if (FLAG_trace_gc_verbose) {
99 heap()->isolate()->PrintWithTimestamp(
100 "Memory reducer: waiting for %.f ms\n",
101 state_.next_gc_start_ms - event.time_ms);
102 }
103 }
104 }
105
106
NotifyMarkCompact(const Event & event)107 void MemoryReducer::NotifyMarkCompact(const Event& event) {
108 DCHECK_EQ(kMarkCompact, event.type);
109 Action old_action = state_.action;
110 state_ = Step(state_, event);
111 if (old_action != kWait && state_.action == kWait) {
112 // If we are transitioning to the WAIT state, start the timer.
113 ScheduleTimer(state_.next_gc_start_ms - event.time_ms);
114 }
115 if (old_action == kRun) {
116 if (FLAG_trace_gc_verbose) {
117 heap()->isolate()->PrintWithTimestamp(
118 "Memory reducer: finished GC #%d (%s)\n", state_.started_gcs,
119 state_.action == kWait ? "will do more" : "done");
120 }
121 }
122 }
123
NotifyPossibleGarbage(const Event & event)124 void MemoryReducer::NotifyPossibleGarbage(const Event& event) {
125 DCHECK_EQ(kPossibleGarbage, event.type);
126 Action old_action = state_.action;
127 state_ = Step(state_, event);
128 if (old_action != kWait && state_.action == kWait) {
129 // If we are transitioning to the WAIT state, start the timer.
130 ScheduleTimer(state_.next_gc_start_ms - event.time_ms);
131 }
132 }
133
134
WatchdogGC(const State & state,const Event & event)135 bool MemoryReducer::WatchdogGC(const State& state, const Event& event) {
136 return state.last_gc_time_ms != 0 &&
137 event.time_ms > state.last_gc_time_ms + kWatchdogDelayMs;
138 }
139
140
141 // For specification of this function see the comment for MemoryReducer class.
Step(const State & state,const Event & event)142 MemoryReducer::State MemoryReducer::Step(const State& state,
143 const Event& event) {
144 if (!FLAG_incremental_marking || !FLAG_memory_reducer) {
145 return State(kDone, 0, 0, state.last_gc_time_ms, 0);
146 }
147 switch (state.action) {
148 case kDone:
149 if (event.type == kTimer) {
150 return state;
151 } else if (event.type == kMarkCompact) {
152 if (event.committed_memory <
153 std::max(
154 static_cast<size_t>(state.committed_memory_at_last_run *
155 kCommittedMemoryFactor),
156 state.committed_memory_at_last_run + kCommittedMemoryDelta)) {
157 return state;
158 } else {
159 return State(kWait, 0, event.time_ms + kLongDelayMs,
160 event.type == kMarkCompact ? event.time_ms
161 : state.last_gc_time_ms,
162 0);
163 }
164 } else {
165 DCHECK_EQ(kPossibleGarbage, event.type);
166 return State(
167 kWait, 0, event.time_ms + kLongDelayMs,
168 event.type == kMarkCompact ? event.time_ms : state.last_gc_time_ms,
169 0);
170 }
171 case kWait:
172 switch (event.type) {
173 case kPossibleGarbage:
174 return state;
175 case kTimer:
176 if (state.started_gcs >= kMaxNumberOfGCs) {
177 return State(kDone, kMaxNumberOfGCs, 0.0, state.last_gc_time_ms,
178 event.committed_memory);
179 } else if (event.can_start_incremental_gc &&
180 (event.should_start_incremental_gc ||
181 WatchdogGC(state, event))) {
182 if (state.next_gc_start_ms <= event.time_ms) {
183 return State(kRun, state.started_gcs + 1, 0.0,
184 state.last_gc_time_ms, 0);
185 } else {
186 return state;
187 }
188 } else {
189 return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs,
190 state.last_gc_time_ms, 0);
191 }
192 case kMarkCompact:
193 return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs,
194 event.time_ms, 0);
195 }
196 case kRun:
197 if (event.type != kMarkCompact) {
198 return state;
199 } else {
200 if (state.started_gcs < kMaxNumberOfGCs &&
201 (event.next_gc_likely_to_collect_more || state.started_gcs == 1)) {
202 return State(kWait, state.started_gcs, event.time_ms + kShortDelayMs,
203 event.time_ms, 0);
204 } else {
205 return State(kDone, kMaxNumberOfGCs, 0.0, event.time_ms,
206 event.committed_memory);
207 }
208 }
209 }
210 UNREACHABLE();
211 }
212
ScheduleTimer(double delay_ms)213 void MemoryReducer::ScheduleTimer(double delay_ms) {
214 DCHECK_LT(0, delay_ms);
215 if (heap()->IsTearingDown()) return;
216 // Leave some room for precision error in task scheduler.
217 const double kSlackMs = 100;
218 taskrunner_->PostDelayedTask(std::make_unique<MemoryReducer::TimerTask>(this),
219 (delay_ms + kSlackMs) / 1000.0);
220 }
221
TearDown()222 void MemoryReducer::TearDown() { state_ = State(kDone, 0, 0, 0.0, 0); }
223
224 } // namespace internal
225 } // namespace v8
226