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