| // Copyright 2015 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/heap/memory-reducer.h" |
| |
| #include "src/flags.h" |
| #include "src/heap/gc-tracer.h" |
| #include "src/heap/heap-inl.h" |
| #include "src/utils.h" |
| #include "src/v8.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| const int MemoryReducer::kLongDelayMs = 8000; |
| const int MemoryReducer::kShortDelayMs = 500; |
| const int MemoryReducer::kWatchdogDelayMs = 100000; |
| const int MemoryReducer::kMaxNumberOfGCs = 3; |
| |
| MemoryReducer::TimerTask::TimerTask(MemoryReducer* memory_reducer) |
| : CancelableTask(memory_reducer->heap()->isolate()), |
| memory_reducer_(memory_reducer) {} |
| |
| |
| void MemoryReducer::TimerTask::RunInternal() { |
| const double kJsCallsPerMsThreshold = 0.5; |
| Heap* heap = memory_reducer_->heap(); |
| Event event; |
| double time_ms = heap->MonotonicallyIncreasingTimeInMs(); |
| heap->tracer()->SampleAllocation(time_ms, heap->NewSpaceAllocationCounter(), |
| heap->OldGenerationAllocationCounter()); |
| double js_call_rate = memory_reducer_->SampleAndGetJsCallsPerMs(time_ms); |
| bool low_allocation_rate = heap->HasLowAllocationRate(); |
| bool is_idle = js_call_rate < kJsCallsPerMsThreshold && low_allocation_rate; |
| bool optimize_for_memory = heap->ShouldOptimizeForMemoryUsage(); |
| if (FLAG_trace_gc_verbose) { |
| PrintIsolate(heap->isolate(), "Memory reducer: call rate %.3lf, %s, %s\n", |
| js_call_rate, low_allocation_rate ? "low alloc" : "high alloc", |
| optimize_for_memory ? "background" : "foreground"); |
| } |
| event.type = kTimer; |
| event.time_ms = time_ms; |
| // The memory reducer will start incremental markig if |
| // 1) mutator is likely idle: js call rate is low and allocation rate is low. |
| // 2) mutator is in background: optimize for memory flag is set. |
| event.should_start_incremental_gc = is_idle || optimize_for_memory; |
| event.can_start_incremental_gc = |
| heap->incremental_marking()->IsStopped() && |
| (heap->incremental_marking()->CanBeActivated() || optimize_for_memory); |
| memory_reducer_->NotifyTimer(event); |
| } |
| |
| |
| double MemoryReducer::SampleAndGetJsCallsPerMs(double time_ms) { |
| unsigned int counter = heap()->isolate()->js_calls_from_api_counter(); |
| unsigned int call_delta = counter - js_calls_counter_; |
| double time_delta_ms = time_ms - js_calls_sample_time_ms_; |
| js_calls_counter_ = counter; |
| js_calls_sample_time_ms_ = time_ms; |
| return time_delta_ms > 0 ? call_delta / time_delta_ms : 0; |
| } |
| |
| |
| void MemoryReducer::NotifyTimer(const Event& event) { |
| DCHECK_EQ(kTimer, event.type); |
| DCHECK_EQ(kWait, state_.action); |
| state_ = Step(state_, event); |
| if (state_.action == kRun) { |
| DCHECK(heap()->incremental_marking()->IsStopped()); |
| DCHECK(FLAG_incremental_marking); |
| if (FLAG_trace_gc_verbose) { |
| PrintIsolate(heap()->isolate(), "Memory reducer: started GC #%d\n", |
| state_.started_gcs); |
| } |
| heap()->StartIdleIncrementalMarking(); |
| } else if (state_.action == kWait) { |
| if (!heap()->incremental_marking()->IsStopped() && |
| heap()->ShouldOptimizeForMemoryUsage()) { |
| // Make progress with pending incremental marking if memory usage has |
| // higher priority than latency. This is important for background tabs |
| // that do not send idle notifications. |
| const int kIncrementalMarkingDelayMs = 500; |
| double deadline = heap()->MonotonicallyIncreasingTimeInMs() + |
| kIncrementalMarkingDelayMs; |
| heap()->incremental_marking()->AdvanceIncrementalMarking( |
| deadline, i::IncrementalMarking::StepActions( |
| i::IncrementalMarking::NO_GC_VIA_STACK_GUARD, |
| i::IncrementalMarking::FORCE_MARKING, |
| i::IncrementalMarking::FORCE_COMPLETION)); |
| heap()->FinalizeIncrementalMarkingIfComplete( |
| "Memory reducer: finalize incremental marking"); |
| } |
| // Re-schedule the timer. |
| ScheduleTimer(event.time_ms, state_.next_gc_start_ms - event.time_ms); |
| if (FLAG_trace_gc_verbose) { |
| PrintIsolate(heap()->isolate(), "Memory reducer: waiting for %.f ms\n", |
| state_.next_gc_start_ms - event.time_ms); |
| } |
| } |
| } |
| |
| |
| void MemoryReducer::NotifyMarkCompact(const Event& event) { |
| DCHECK_EQ(kMarkCompact, event.type); |
| Action old_action = state_.action; |
| state_ = Step(state_, event); |
| if (old_action != kWait && state_.action == kWait) { |
| // If we are transitioning to the WAIT state, start the timer. |
| ScheduleTimer(event.time_ms, state_.next_gc_start_ms - event.time_ms); |
| } |
| if (old_action == kRun) { |
| if (FLAG_trace_gc_verbose) { |
| PrintIsolate(heap()->isolate(), "Memory reducer: finished GC #%d (%s)\n", |
| state_.started_gcs, |
| state_.action == kWait ? "will do more" : "done"); |
| } |
| } |
| } |
| |
| void MemoryReducer::NotifyPossibleGarbage(const Event& event) { |
| DCHECK_EQ(kPossibleGarbage, event.type); |
| Action old_action = state_.action; |
| state_ = Step(state_, event); |
| if (old_action != kWait && state_.action == kWait) { |
| // If we are transitioning to the WAIT state, start the timer. |
| ScheduleTimer(event.time_ms, state_.next_gc_start_ms - event.time_ms); |
| } |
| } |
| |
| |
| bool MemoryReducer::WatchdogGC(const State& state, const Event& event) { |
| return state.last_gc_time_ms != 0 && |
| event.time_ms > state.last_gc_time_ms + kWatchdogDelayMs; |
| } |
| |
| |
| // For specification of this function see the comment for MemoryReducer class. |
| MemoryReducer::State MemoryReducer::Step(const State& state, |
| const Event& event) { |
| if (!FLAG_incremental_marking || !FLAG_memory_reducer) { |
| return State(kDone, 0, 0, state.last_gc_time_ms); |
| } |
| switch (state.action) { |
| case kDone: |
| if (event.type == kTimer) { |
| return state; |
| } else { |
| DCHECK(event.type == kPossibleGarbage || event.type == kMarkCompact); |
| return State( |
| kWait, 0, event.time_ms + kLongDelayMs, |
| event.type == kMarkCompact ? event.time_ms : state.last_gc_time_ms); |
| } |
| case kWait: |
| switch (event.type) { |
| case kPossibleGarbage: |
| return state; |
| case kTimer: |
| if (state.started_gcs >= kMaxNumberOfGCs) { |
| return State(kDone, kMaxNumberOfGCs, 0.0, state.last_gc_time_ms); |
| } else if (event.can_start_incremental_gc && |
| (event.should_start_incremental_gc || |
| WatchdogGC(state, event))) { |
| if (state.next_gc_start_ms <= event.time_ms) { |
| return State(kRun, state.started_gcs + 1, 0.0, |
| state.last_gc_time_ms); |
| } else { |
| return state; |
| } |
| } else { |
| return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs, |
| state.last_gc_time_ms); |
| } |
| case kMarkCompact: |
| return State(kWait, state.started_gcs, event.time_ms + kLongDelayMs, |
| event.time_ms); |
| } |
| case kRun: |
| if (event.type != kMarkCompact) { |
| return state; |
| } else { |
| if (state.started_gcs < kMaxNumberOfGCs && |
| (event.next_gc_likely_to_collect_more || state.started_gcs == 1)) { |
| return State(kWait, state.started_gcs, event.time_ms + kShortDelayMs, |
| event.time_ms); |
| } else { |
| return State(kDone, kMaxNumberOfGCs, 0.0, event.time_ms); |
| } |
| } |
| } |
| UNREACHABLE(); |
| return State(kDone, 0, 0, 0.0); // Make the compiler happy. |
| } |
| |
| |
| void MemoryReducer::ScheduleTimer(double time_ms, double delay_ms) { |
| DCHECK(delay_ms > 0); |
| // Record the time and the js call counter. |
| SampleAndGetJsCallsPerMs(time_ms); |
| // Leave some room for precision error in task scheduler. |
| const double kSlackMs = 100; |
| v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(heap()->isolate()); |
| auto timer_task = new MemoryReducer::TimerTask(this); |
| V8::GetCurrentPlatform()->CallDelayedOnForegroundThread( |
| isolate, timer_task, (delay_ms + kSlackMs) / 1000.0); |
| } |
| |
| |
| void MemoryReducer::TearDown() { state_ = State(kDone, 0, 0, 0.0); } |
| |
| } // namespace internal |
| } // namespace v8 |
