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// Copyright 2014 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/gc-idle-time-handler.h"
#include "src/flags.h"
#include "src/heap/gc-tracer.h"
#include "src/utils.h"
namespace v8 {
namespace internal {
const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
void GCIdleTimeHeapState::Print() {
PrintF("contexts_disposed=%d ", contexts_disposed);
PrintF("contexts_disposal_rate=%f ", contexts_disposal_rate);
PrintF("size_of_objects=%" PRIuS " ", size_of_objects);
PrintF("incremental_marking_stopped=%d ", incremental_marking_stopped);
}
size_t GCIdleTimeHandler::EstimateMarkingStepSize(
double idle_time_in_ms, double marking_speed_in_bytes_per_ms) {
DCHECK_LT(0, idle_time_in_ms);
if (marking_speed_in_bytes_per_ms == 0) {
marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
}
double marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
if (marking_step_size >= kMaximumMarkingStepSize) {
return kMaximumMarkingStepSize;
}
return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
}
double GCIdleTimeHandler::EstimateFinalIncrementalMarkCompactTime(
size_t size_of_objects,
double final_incremental_mark_compact_speed_in_bytes_per_ms) {
if (final_incremental_mark_compact_speed_in_bytes_per_ms == 0) {
final_incremental_mark_compact_speed_in_bytes_per_ms =
kInitialConservativeFinalIncrementalMarkCompactSpeed;
}
double result =
size_of_objects / final_incremental_mark_compact_speed_in_bytes_per_ms;
return Min<double>(result, kMaxFinalIncrementalMarkCompactTimeInMs);
}
bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
int contexts_disposed, double contexts_disposal_rate,
size_t size_of_objects) {
return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
contexts_disposal_rate < kHighContextDisposalRate &&
size_of_objects <= kMaxHeapSizeForContextDisposalMarkCompact;
}
bool GCIdleTimeHandler::ShouldDoFinalIncrementalMarkCompact(
double idle_time_in_ms, size_t size_of_objects,
double final_incremental_mark_compact_speed_in_bytes_per_ms) {
return idle_time_in_ms >=
EstimateFinalIncrementalMarkCompactTime(
size_of_objects,
final_incremental_mark_compact_speed_in_bytes_per_ms);
}
bool GCIdleTimeHandler::ShouldDoOverApproximateWeakClosure(
double idle_time_in_ms) {
// TODO(jochen): Estimate the time it will take to build the object groups.
return idle_time_in_ms >= kMinTimeForOverApproximatingWeakClosureInMs;
}
// The following logic is implemented by the controller:
// (1) If we don't have any idle time, do nothing, unless a context was
// disposed, incremental marking is stopped, and the heap is small. Then do
// a full GC.
// (2) If the context disposal rate is high and we cannot perform a full GC,
// we do nothing until the context disposal rate becomes lower.
// (3) If the new space is almost full and we can afford a scavenge or if the
// next scavenge will very likely take long, then a scavenge is performed.
// (4) If sweeping is in progress and we received a large enough idle time
// request, we finalize sweeping here.
// (5) If incremental marking is in progress, we perform a marking step. Note,
// that this currently may trigger a full garbage collection.
GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
GCIdleTimeHeapState heap_state) {
if (static_cast<int>(idle_time_in_ms) <= 0) {
if (heap_state.incremental_marking_stopped) {
if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
heap_state.contexts_disposal_rate,
heap_state.size_of_objects)) {
return GCIdleTimeAction::kFullGC;
}
}
return GCIdleTimeAction::kDone;
}
if (FLAG_incremental_marking && !heap_state.incremental_marking_stopped) {
return GCIdleTimeAction::kIncrementalStep;
}
return GCIdleTimeAction::kDone;
}
bool GCIdleTimeHandler::Enabled() { return FLAG_incremental_marking; }
} // namespace internal
} // namespace v8
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