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 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 31 MemoryReducer::TimerTask::TimerTask(MemoryReducer* memory_reducer) 32 : CancelableTask(memory_reducer->heap()->isolate()), 33 memory_reducer_(memory_reducer) {} 34 35 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 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 } 103 104 105 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 } 121 122 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 } 131 132 133 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. 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 } 209 210 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 } 219 220 void MemoryReducer::TearDown() { state_ = State(kDone, 0, 0, 0.0, 0); } 221 222 } // namespace internal 223 } // namespace v8 224
