1 // Copyright 2014 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.
5 #include "src/heap/gc-idle-time-handler.h"
8 #include "src/heap/gc-tracer.h"
14 const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
15 const size_t GCIdleTimeHandler::kMaxMarkCompactTimeInMs = 1000;
16 const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
17 const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
18 const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
21 void GCIdleTimeAction::Print() {
29 case DO_INCREMENTAL_STEP:
30 PrintF("incremental step");
31 if (additional_work) {
32 PrintF("; finalized marking");
42 void GCIdleTimeHeapState::Print() {
43 PrintF("contexts_disposed=%d ", contexts_disposed);
44 PrintF("contexts_disposal_rate=%f ", contexts_disposal_rate);
45 PrintF("size_of_objects=%" V8_PTR_PREFIX "d ", size_of_objects);
46 PrintF("incremental_marking_stopped=%d ", incremental_marking_stopped);
47 PrintF("sweeping_in_progress=%d ", sweeping_in_progress);
48 PrintF("has_low_allocation_rate=%d", has_low_allocation_rate);
49 PrintF("mark_compact_speed=%" V8_PTR_PREFIX "d ",
50 mark_compact_speed_in_bytes_per_ms);
51 PrintF("incremental_marking_speed=%" V8_PTR_PREFIX "d ",
52 incremental_marking_speed_in_bytes_per_ms);
56 size_t GCIdleTimeHandler::EstimateMarkingStepSize(
57 size_t idle_time_in_ms, size_t marking_speed_in_bytes_per_ms) {
58 DCHECK(idle_time_in_ms > 0);
60 if (marking_speed_in_bytes_per_ms == 0) {
61 marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
64 size_t marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
65 if (marking_step_size / marking_speed_in_bytes_per_ms != idle_time_in_ms) {
66 // In the case of an overflow we return maximum marking step size.
67 return kMaximumMarkingStepSize;
70 if (marking_step_size > kMaximumMarkingStepSize)
71 return kMaximumMarkingStepSize;
73 return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
77 size_t GCIdleTimeHandler::EstimateMarkCompactTime(
78 size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms) {
79 // TODO(hpayer): Be more precise about the type of mark-compact event. It
80 // makes a huge difference if compaction is happening.
81 if (mark_compact_speed_in_bytes_per_ms == 0) {
82 mark_compact_speed_in_bytes_per_ms = kInitialConservativeMarkCompactSpeed;
84 size_t result = size_of_objects / mark_compact_speed_in_bytes_per_ms;
85 return Min(result, kMaxMarkCompactTimeInMs);
89 size_t GCIdleTimeHandler::EstimateFinalIncrementalMarkCompactTime(
90 size_t size_of_objects,
91 size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
92 if (final_incremental_mark_compact_speed_in_bytes_per_ms == 0) {
93 final_incremental_mark_compact_speed_in_bytes_per_ms =
94 kInitialConservativeFinalIncrementalMarkCompactSpeed;
97 size_of_objects / final_incremental_mark_compact_speed_in_bytes_per_ms;
98 return Min(result, kMaxFinalIncrementalMarkCompactTimeInMs);
102 bool GCIdleTimeHandler::ShouldDoMarkCompact(
103 size_t idle_time_in_ms, size_t size_of_objects,
104 size_t mark_compact_speed_in_bytes_per_ms) {
105 return idle_time_in_ms >= kMaxScheduledIdleTime &&
107 EstimateMarkCompactTime(size_of_objects,
108 mark_compact_speed_in_bytes_per_ms);
112 bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
113 int contexts_disposed, double contexts_disposal_rate) {
114 return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
115 contexts_disposal_rate < kHighContextDisposalRate;
119 bool GCIdleTimeHandler::ShouldDoFinalIncrementalMarkCompact(
120 size_t idle_time_in_ms, size_t size_of_objects,
121 size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
122 return idle_time_in_ms >=
123 EstimateFinalIncrementalMarkCompactTime(
125 final_incremental_mark_compact_speed_in_bytes_per_ms);
129 bool GCIdleTimeHandler::ShouldDoOverApproximateWeakClosure(
130 size_t idle_time_in_ms) {
131 // TODO(jochen): Estimate the time it will take to build the object groups.
132 return idle_time_in_ms >= kMinTimeForOverApproximatingWeakClosureInMs;
136 GCIdleTimeAction GCIdleTimeHandler::NothingOrDone(double idle_time_in_ms) {
137 if (idle_time_in_ms >= kMinBackgroundIdleTime) {
138 return GCIdleTimeAction::Nothing();
140 if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes) {
141 return GCIdleTimeAction::Done();
143 idle_times_which_made_no_progress_++;
144 return GCIdleTimeAction::Nothing();
149 // The following logic is implemented by the controller:
150 // (1) If we don't have any idle time, do nothing, unless a context was
151 // disposed, incremental marking is stopped, and the heap is small. Then do
153 // (2) If the context disposal rate is high and we cannot perform a full GC,
154 // we do nothing until the context disposal rate becomes lower.
155 // (3) If the new space is almost full and we can affort a scavenge or if the
156 // next scavenge will very likely take long, then a scavenge is performed.
157 // (4) If sweeping is in progress and we received a large enough idle time
158 // request, we finalize sweeping here.
159 // (5) If incremental marking is in progress, we perform a marking step. Note,
160 // that this currently may trigger a full garbage collection.
161 GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
162 GCIdleTimeHeapState heap_state) {
163 if (static_cast<int>(idle_time_in_ms) <= 0) {
164 if (heap_state.incremental_marking_stopped) {
165 if (ShouldDoContextDisposalMarkCompact(
166 heap_state.contexts_disposed,
167 heap_state.contexts_disposal_rate)) {
168 return GCIdleTimeAction::FullGC();
171 return GCIdleTimeAction::Nothing();
174 // We are in a context disposal GC scenario. Don't do anything if we do not
175 // get the right idle signal.
176 if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
177 heap_state.contexts_disposal_rate)) {
178 return NothingOrDone(idle_time_in_ms);
181 if (!FLAG_incremental_marking || heap_state.incremental_marking_stopped) {
182 return GCIdleTimeAction::Done();
185 return GCIdleTimeAction::IncrementalStep();