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.
4
5 #include "src/heap/gc-idle-time-handler.h"
6 #include "src/heap/gc-tracer.h"
7 #include "src/utils.h"
8
9 namespace v8 {
10 namespace internal {
11
12 const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
13 const size_t GCIdleTimeHandler::kMaxMarkCompactTimeInMs = 1000;
14 const size_t GCIdleTimeHandler::kMinTimeForFinalizeSweeping = 100;
15 const int GCIdleTimeHandler::kMaxMarkCompactsInIdleRound = 7;
16 const int GCIdleTimeHandler::kIdleScavengeThreshold = 5;
17
18
Print()19 void GCIdleTimeAction::Print() {
20 switch (type) {
21 case DONE:
22 PrintF("done");
23 break;
24 case DO_NOTHING:
25 PrintF("no action");
26 break;
27 case DO_INCREMENTAL_MARKING:
28 PrintF("incremental marking with step %" V8_PTR_PREFIX "d", parameter);
29 break;
30 case DO_SCAVENGE:
31 PrintF("scavenge");
32 break;
33 case DO_FULL_GC:
34 PrintF("full GC");
35 break;
36 case DO_FINALIZE_SWEEPING:
37 PrintF("finalize sweeping");
38 break;
39 }
40 }
41
42
EstimateMarkingStepSize(size_t idle_time_in_ms,size_t marking_speed_in_bytes_per_ms)43 size_t GCIdleTimeHandler::EstimateMarkingStepSize(
44 size_t idle_time_in_ms, size_t marking_speed_in_bytes_per_ms) {
45 DCHECK(idle_time_in_ms > 0);
46
47 if (marking_speed_in_bytes_per_ms == 0) {
48 marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
49 }
50
51 size_t marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
52 if (marking_step_size / marking_speed_in_bytes_per_ms != idle_time_in_ms) {
53 // In the case of an overflow we return maximum marking step size.
54 return kMaximumMarkingStepSize;
55 }
56
57 if (marking_step_size > kMaximumMarkingStepSize)
58 return kMaximumMarkingStepSize;
59
60 return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
61 }
62
63
EstimateMarkCompactTime(size_t size_of_objects,size_t mark_compact_speed_in_bytes_per_ms)64 size_t GCIdleTimeHandler::EstimateMarkCompactTime(
65 size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms) {
66 if (mark_compact_speed_in_bytes_per_ms == 0) {
67 mark_compact_speed_in_bytes_per_ms = kInitialConservativeMarkCompactSpeed;
68 }
69 size_t result = size_of_objects / mark_compact_speed_in_bytes_per_ms;
70 return Min(result, kMaxMarkCompactTimeInMs);
71 }
72
73
EstimateScavengeTime(size_t new_space_size,size_t scavenge_speed_in_bytes_per_ms)74 size_t GCIdleTimeHandler::EstimateScavengeTime(
75 size_t new_space_size, size_t scavenge_speed_in_bytes_per_ms) {
76 if (scavenge_speed_in_bytes_per_ms == 0) {
77 scavenge_speed_in_bytes_per_ms = kInitialConservativeScavengeSpeed;
78 }
79 return new_space_size / scavenge_speed_in_bytes_per_ms;
80 }
81
82
ScavangeMayHappenSoon(size_t available_new_space_memory,size_t new_space_allocation_throughput_in_bytes_per_ms)83 bool GCIdleTimeHandler::ScavangeMayHappenSoon(
84 size_t available_new_space_memory,
85 size_t new_space_allocation_throughput_in_bytes_per_ms) {
86 if (available_new_space_memory <=
87 new_space_allocation_throughput_in_bytes_per_ms *
88 kMaxFrameRenderingIdleTime) {
89 return true;
90 }
91 return false;
92 }
93
94
95 // The following logic is implemented by the controller:
96 // (1) If the new space is almost full and we can effort a Scavenge, then a
97 // Scavenge is performed.
98 // (2) If there is currently no MarkCompact idle round going on, we start a
99 // new idle round if enough garbage was created or we received a context
100 // disposal event. Otherwise we do not perform garbage collection to keep
101 // system utilization low.
102 // (3) If incremental marking is done, we perform a full garbage collection
103 // if context was disposed or if we are allowed to still do full garbage
104 // collections during this idle round or if we are not allowed to start
105 // incremental marking. Otherwise we do not perform garbage collection to
106 // keep system utilization low.
107 // (4) If sweeping is in progress and we received a large enough idle time
108 // request, we finalize sweeping here.
109 // (5) If incremental marking is in progress, we perform a marking step. Note,
110 // that this currently may trigger a full garbage collection.
Compute(size_t idle_time_in_ms,HeapState heap_state)111 GCIdleTimeAction GCIdleTimeHandler::Compute(size_t idle_time_in_ms,
112 HeapState heap_state) {
113 if (idle_time_in_ms <= kMaxFrameRenderingIdleTime &&
114 ScavangeMayHappenSoon(
115 heap_state.available_new_space_memory,
116 heap_state.new_space_allocation_throughput_in_bytes_per_ms) &&
117 idle_time_in_ms >=
118 EstimateScavengeTime(heap_state.new_space_capacity,
119 heap_state.scavenge_speed_in_bytes_per_ms)) {
120 return GCIdleTimeAction::Scavenge();
121 }
122 if (IsMarkCompactIdleRoundFinished()) {
123 if (EnoughGarbageSinceLastIdleRound() || heap_state.contexts_disposed > 0) {
124 StartIdleRound();
125 } else {
126 return GCIdleTimeAction::Done();
127 }
128 }
129
130 if (idle_time_in_ms == 0) {
131 return GCIdleTimeAction::Nothing();
132 }
133
134 if (heap_state.incremental_marking_stopped) {
135 size_t estimated_time_in_ms =
136 EstimateMarkCompactTime(heap_state.size_of_objects,
137 heap_state.mark_compact_speed_in_bytes_per_ms);
138 if (idle_time_in_ms >= estimated_time_in_ms ||
139 (heap_state.size_of_objects < kSmallHeapSize &&
140 heap_state.contexts_disposed > 0)) {
141 // If there are no more than two GCs left in this idle round and we are
142 // allowed to do a full GC, then make those GCs full in order to compact
143 // the code space.
144 // TODO(ulan): Once we enable code compaction for incremental marking, we
145 // can get rid of this special case and always start incremental marking.
146 int remaining_mark_sweeps =
147 kMaxMarkCompactsInIdleRound - mark_compacts_since_idle_round_started_;
148 if (heap_state.contexts_disposed > 0 ||
149 (idle_time_in_ms > kMaxFrameRenderingIdleTime &&
150 (remaining_mark_sweeps <= 2 ||
151 !heap_state.can_start_incremental_marking))) {
152 return GCIdleTimeAction::FullGC();
153 }
154 }
155 if (!heap_state.can_start_incremental_marking) {
156 return GCIdleTimeAction::Nothing();
157 }
158 }
159 // TODO(hpayer): Estimate finalize sweeping time.
160 if (heap_state.sweeping_in_progress &&
161 idle_time_in_ms >= kMinTimeForFinalizeSweeping) {
162 return GCIdleTimeAction::FinalizeSweeping();
163 }
164
165 if (heap_state.incremental_marking_stopped &&
166 !heap_state.can_start_incremental_marking) {
167 return GCIdleTimeAction::Nothing();
168 }
169 size_t step_size = EstimateMarkingStepSize(
170 idle_time_in_ms, heap_state.incremental_marking_speed_in_bytes_per_ms);
171 return GCIdleTimeAction::IncrementalMarking(step_size);
172 }
173 }
174 }
175