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