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
7 #include "src/flags.h"
8 #include "src/heap/gc-tracer.h"
9 #include "src/utils.h"
10
11 namespace v8 {
12 namespace internal {
13
14 const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
15 const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
16 const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
17 const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
18
19
Print()20 void GCIdleTimeAction::Print() {
21 switch (type) {
22 case DONE:
23 PrintF("done");
24 break;
25 case DO_NOTHING:
26 PrintF("no action");
27 break;
28 case DO_INCREMENTAL_STEP:
29 PrintF("incremental step");
30 if (additional_work) {
31 PrintF("; finalized marking");
32 }
33 break;
34 case DO_FULL_GC:
35 PrintF("full GC");
36 break;
37 }
38 }
39
40
Print()41 void GCIdleTimeHeapState::Print() {
42 PrintF("contexts_disposed=%d ", contexts_disposed);
43 PrintF("contexts_disposal_rate=%f ", contexts_disposal_rate);
44 PrintF("size_of_objects=%" PRIuS " ", size_of_objects);
45 PrintF("incremental_marking_stopped=%d ", incremental_marking_stopped);
46 }
47
EstimateMarkingStepSize(double idle_time_in_ms,double marking_speed_in_bytes_per_ms)48 size_t GCIdleTimeHandler::EstimateMarkingStepSize(
49 double idle_time_in_ms, double marking_speed_in_bytes_per_ms) {
50 DCHECK(idle_time_in_ms > 0);
51
52 if (marking_speed_in_bytes_per_ms == 0) {
53 marking_speed_in_bytes_per_ms = kInitialConservativeMarkingSpeed;
54 }
55
56 double marking_step_size = marking_speed_in_bytes_per_ms * idle_time_in_ms;
57 if (marking_step_size >= kMaximumMarkingStepSize) {
58 return kMaximumMarkingStepSize;
59 }
60 return static_cast<size_t>(marking_step_size * kConservativeTimeRatio);
61 }
62
EstimateFinalIncrementalMarkCompactTime(size_t size_of_objects,double final_incremental_mark_compact_speed_in_bytes_per_ms)63 double GCIdleTimeHandler::EstimateFinalIncrementalMarkCompactTime(
64 size_t size_of_objects,
65 double final_incremental_mark_compact_speed_in_bytes_per_ms) {
66 if (final_incremental_mark_compact_speed_in_bytes_per_ms == 0) {
67 final_incremental_mark_compact_speed_in_bytes_per_ms =
68 kInitialConservativeFinalIncrementalMarkCompactSpeed;
69 }
70 double result =
71 size_of_objects / final_incremental_mark_compact_speed_in_bytes_per_ms;
72 return Min<double>(result, kMaxFinalIncrementalMarkCompactTimeInMs);
73 }
74
ShouldDoContextDisposalMarkCompact(int contexts_disposed,double contexts_disposal_rate)75 bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
76 int contexts_disposed, double contexts_disposal_rate) {
77 return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
78 contexts_disposal_rate < kHighContextDisposalRate;
79 }
80
ShouldDoFinalIncrementalMarkCompact(double idle_time_in_ms,size_t size_of_objects,double final_incremental_mark_compact_speed_in_bytes_per_ms)81 bool GCIdleTimeHandler::ShouldDoFinalIncrementalMarkCompact(
82 double idle_time_in_ms, size_t size_of_objects,
83 double final_incremental_mark_compact_speed_in_bytes_per_ms) {
84 return idle_time_in_ms >=
85 EstimateFinalIncrementalMarkCompactTime(
86 size_of_objects,
87 final_incremental_mark_compact_speed_in_bytes_per_ms);
88 }
89
ShouldDoOverApproximateWeakClosure(double idle_time_in_ms)90 bool GCIdleTimeHandler::ShouldDoOverApproximateWeakClosure(
91 double idle_time_in_ms) {
92 // TODO(jochen): Estimate the time it will take to build the object groups.
93 return idle_time_in_ms >= kMinTimeForOverApproximatingWeakClosureInMs;
94 }
95
96
NothingOrDone(double idle_time_in_ms)97 GCIdleTimeAction GCIdleTimeHandler::NothingOrDone(double idle_time_in_ms) {
98 if (idle_time_in_ms >= kMinBackgroundIdleTime) {
99 return GCIdleTimeAction::Nothing();
100 }
101 if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes) {
102 return GCIdleTimeAction::Done();
103 } else {
104 idle_times_which_made_no_progress_++;
105 return GCIdleTimeAction::Nothing();
106 }
107 }
108
109
110 // The following logic is implemented by the controller:
111 // (1) If we don't have any idle time, do nothing, unless a context was
112 // disposed, incremental marking is stopped, and the heap is small. Then do
113 // a full GC.
114 // (2) If the context disposal rate is high and we cannot perform a full GC,
115 // we do nothing until the context disposal rate becomes lower.
116 // (3) If the new space is almost full and we can affort a scavenge or if the
117 // next scavenge will very likely take long, then a scavenge is performed.
118 // (4) If sweeping is in progress and we received a large enough idle time
119 // request, we finalize sweeping here.
120 // (5) If incremental marking is in progress, we perform a marking step. Note,
121 // that this currently may trigger a full garbage collection.
Compute(double idle_time_in_ms,GCIdleTimeHeapState heap_state)122 GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
123 GCIdleTimeHeapState heap_state) {
124 if (static_cast<int>(idle_time_in_ms) <= 0) {
125 if (heap_state.incremental_marking_stopped) {
126 if (ShouldDoContextDisposalMarkCompact(
127 heap_state.contexts_disposed,
128 heap_state.contexts_disposal_rate)) {
129 return GCIdleTimeAction::FullGC();
130 }
131 }
132 return GCIdleTimeAction::Nothing();
133 }
134
135 // We are in a context disposal GC scenario. Don't do anything if we do not
136 // get the right idle signal.
137 if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
138 heap_state.contexts_disposal_rate)) {
139 return NothingOrDone(idle_time_in_ms);
140 }
141
142 if (!FLAG_incremental_marking || heap_state.incremental_marking_stopped) {
143 return GCIdleTimeAction::Done();
144 }
145
146 return GCIdleTimeAction::IncrementalStep();
147 }
148
Enabled()149 bool GCIdleTimeHandler::Enabled() { return FLAG_incremental_marking; }
150
151 } // namespace internal
152 } // namespace v8
153