// Copyright 2014 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/heap/gc-idle-time-handler.h"
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#include "src/flags.h"
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#include "src/heap/gc-tracer.h"
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#include "src/utils.h"
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namespace v8 {
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namespace internal {
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const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
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const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
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const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
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const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
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void GCIdleTimeAction::Print() {
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switch (type) {
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case DONE:
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PrintF("done");
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break;
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case DO_NOTHING:
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PrintF("no action");
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break;
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case DO_INCREMENTAL_STEP:
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PrintF("incremental step");
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if (additional_work) {
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PrintF("; finalized marking");
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}
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break;
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case DO_FULL_GC:
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PrintF("full GC");
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break;
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}
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}
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void GCIdleTimeHeapState::Print() {
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PrintF("contexts_disposed=%d ", contexts_disposed);
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PrintF("contexts_disposal_rate=%f ", contexts_disposal_rate);
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PrintF("size_of_objects=%" PRIuS " ", size_of_objects);
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PrintF("incremental_marking_stopped=%d ", incremental_marking_stopped);
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}
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size_t GCIdleTimeHandler::EstimateMarkingStepSize(
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double idle_time_in_ms, double marking_speed_in_bytes_per_ms) {
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DCHECK_LT(0, idle_time_in_ms);
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if (marking_speed_in_bytes_per_ms == 0) {
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marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
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}
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double marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
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if (marking_step_size >= kMaximumMarkingStepSize) {
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return kMaximumMarkingStepSize;
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}
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return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
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}
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double GCIdleTimeHandler::EstimateFinalIncrementalMarkCompactTime(
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size_t size_of_objects,
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double final_incremental_mark_compact_speed_in_bytes_per_ms) {
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if (final_incremental_mark_compact_speed_in_bytes_per_ms == 0) {
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final_incremental_mark_compact_speed_in_bytes_per_ms =
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kInitialConservativeFinalIncrementalMarkCompactSpeed;
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}
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double result =
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size_of_objects / final_incremental_mark_compact_speed_in_bytes_per_ms;
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return Min<double>(result, kMaxFinalIncrementalMarkCompactTimeInMs);
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}
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bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
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int contexts_disposed, double contexts_disposal_rate,
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size_t size_of_objects) {
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return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
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contexts_disposal_rate < kHighContextDisposalRate &&
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size_of_objects <= kMaxHeapSizeForContextDisposalMarkCompact;
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}
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bool GCIdleTimeHandler::ShouldDoFinalIncrementalMarkCompact(
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double idle_time_in_ms, size_t size_of_objects,
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double final_incremental_mark_compact_speed_in_bytes_per_ms) {
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return idle_time_in_ms >=
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EstimateFinalIncrementalMarkCompactTime(
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size_of_objects,
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final_incremental_mark_compact_speed_in_bytes_per_ms);
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}
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bool GCIdleTimeHandler::ShouldDoOverApproximateWeakClosure(
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double idle_time_in_ms) {
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// TODO(jochen): Estimate the time it will take to build the object groups.
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return idle_time_in_ms >= kMinTimeForOverApproximatingWeakClosureInMs;
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}
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GCIdleTimeAction GCIdleTimeHandler::NothingOrDone(double idle_time_in_ms) {
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if (idle_time_in_ms >= kMinBackgroundIdleTime) {
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return GCIdleTimeAction::Nothing();
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}
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if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes) {
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return GCIdleTimeAction::Done();
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} else {
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idle_times_which_made_no_progress_++;
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return GCIdleTimeAction::Nothing();
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}
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}
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// The following logic is implemented by the controller:
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// (1) If we don't have any idle time, do nothing, unless a context was
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// disposed, incremental marking is stopped, and the heap is small. Then do
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// a full GC.
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// (2) If the context disposal rate is high and we cannot perform a full GC,
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// we do nothing until the context disposal rate becomes lower.
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// (3) If the new space is almost full and we can afford a scavenge or if the
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// next scavenge will very likely take long, then a scavenge is performed.
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// (4) If sweeping is in progress and we received a large enough idle time
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// request, we finalize sweeping here.
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// (5) If incremental marking is in progress, we perform a marking step. Note,
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// that this currently may trigger a full garbage collection.
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GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
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GCIdleTimeHeapState heap_state) {
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if (static_cast<int>(idle_time_in_ms) <= 0) {
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if (heap_state.incremental_marking_stopped) {
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if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
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heap_state.contexts_disposal_rate,
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heap_state.size_of_objects)) {
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return GCIdleTimeAction::FullGC();
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}
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}
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return GCIdleTimeAction::Nothing();
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}
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// We are in a context disposal GC scenario. Don't do anything if we do not
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// get the right idle signal.
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if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
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heap_state.contexts_disposal_rate,
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heap_state.size_of_objects)) {
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return NothingOrDone(idle_time_in_ms);
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}
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if (!FLAG_incremental_marking || heap_state.incremental_marking_stopped) {
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return GCIdleTimeAction::Done();
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}
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return GCIdleTimeAction::IncrementalStep();
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}
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bool GCIdleTimeHandler::Enabled() { return FLAG_incremental_marking; }
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} // namespace internal
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} // namespace v8
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