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