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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::kMaxMarkCompactTimeInMs = 1000;
const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
void GCIdleTimeAction::Print() {
switch (type) {
case DONE:
PrintF("done");
break;
case DO_NOTHING:
PrintF("no action");
break;
case DO_INCREMENTAL_STEP:
PrintF("incremental step");
if (additional_work) {
PrintF("; finalized marking");
}
break;
case DO_FULL_GC:
PrintF("full GC");
break;
}
}
void GCIdleTimeHeapState::Print() {
PrintF("contexts_disposed=%d ", contexts_disposed);
PrintF("contexts_disposal_rate=%f ", contexts_disposal_rate);
PrintF("size_of_objects=%" V8_PTR_PREFIX "d ", size_of_objects);
PrintF("incremental_marking_stopped=%d ", incremental_marking_stopped);
}
size_t GCIdleTimeHandler::EstimateMarkingStepSize(
size_t idle_time_in_ms, size_t marking_speed_in_bytes_per_ms) {
DCHECK(idle_time_in_ms > 0);
if (marking_speed_in_bytes_per_ms == 0) {
marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
}
size_t marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
if (marking_step_size / marking_speed_in_bytes_per_ms != idle_time_in_ms) {
// In the case of an overflow we return maximum marking step size.
return kMaximumMarkingStepSize;
}
if (marking_step_size > kMaximumMarkingStepSize)
return kMaximumMarkingStepSize;
return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
}
size_t GCIdleTimeHandler::EstimateMarkCompactTime(
size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms) {
// TODO(hpayer): Be more precise about the type of mark-compact event. It
// makes a huge difference if compaction is happening.
if (mark_compact_speed_in_bytes_per_ms == 0) {
mark_compact_speed_in_bytes_per_ms = kInitialConservativeMarkCompactSpeed;
}
size_t result = size_of_objects / mark_compact_speed_in_bytes_per_ms;
return Min(result, kMaxMarkCompactTimeInMs);
}
size_t GCIdleTimeHandler::EstimateFinalIncrementalMarkCompactTime(
size_t size_of_objects,
size_t 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;
}
size_t result =
size_of_objects / final_incremental_mark_compact_speed_in_bytes_per_ms;
return Min(result, kMaxFinalIncrementalMarkCompactTimeInMs);
}
bool GCIdleTimeHandler::ShouldDoMarkCompact(
size_t idle_time_in_ms, size_t size_of_objects,
size_t mark_compact_speed_in_bytes_per_ms) {
return idle_time_in_ms >= kMaxScheduledIdleTime &&
idle_time_in_ms >=
EstimateMarkCompactTime(size_of_objects,
mark_compact_speed_in_bytes_per_ms);
}
bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
int contexts_disposed, double contexts_disposal_rate) {
return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
contexts_disposal_rate < kHighContextDisposalRate;
}
bool GCIdleTimeHandler::ShouldDoFinalIncrementalMarkCompact(
size_t idle_time_in_ms, size_t size_of_objects,
size_t 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(
size_t idle_time_in_ms) {
// TODO(jochen): Estimate the time it will take to build the object groups.
return idle_time_in_ms >= kMinTimeForOverApproximatingWeakClosureInMs;
}
GCIdleTimeAction GCIdleTimeHandler::NothingOrDone(double idle_time_in_ms) {
if (idle_time_in_ms >= kMinBackgroundIdleTime) {
return GCIdleTimeAction::Nothing();
}
if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes) {
return GCIdleTimeAction::Done();
} else {
idle_times_which_made_no_progress_++;
return GCIdleTimeAction::Nothing();
}
}
// 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 affort 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)) {
return GCIdleTimeAction::FullGC();
}
}
return GCIdleTimeAction::Nothing();
}
// We are in a context disposal GC scenario. Don't do anything if we do not
// get the right idle signal.
if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
heap_state.contexts_disposal_rate)) {
return NothingOrDone(idle_time_in_ms);
}
if (!FLAG_incremental_marking || heap_state.incremental_marking_stopped) {
return GCIdleTimeAction::Done();
}
return GCIdleTimeAction::IncrementalStep();
}
} // namespace internal
} // namespace v8
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