1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
// 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/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::kMinTimeForFinalizeSweeping = 100;
const int GCIdleTimeHandler::kMaxMarkCompactsInIdleRound = 7;
const int GCIdleTimeHandler::kIdleScavengeThreshold = 5;
void GCIdleTimeAction::Print() {
switch (type) {
case DONE:
PrintF("done");
break;
case DO_NOTHING:
PrintF("no action");
break;
case DO_INCREMENTAL_MARKING:
PrintF("incremental marking with step %" V8_PTR_PREFIX "d", parameter);
break;
case DO_SCAVENGE:
PrintF("scavenge");
break;
case DO_FULL_GC:
PrintF("full GC");
break;
case DO_FINALIZE_SWEEPING:
PrintF("finalize sweeping");
break;
}
}
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 it is incremental or non-incremental and 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);
}
bool GCIdleTimeHandler::ShouldDoScavenge(
size_t idle_time_in_ms, size_t new_space_size, size_t used_new_space_size,
size_t scavenge_speed_in_bytes_per_ms,
size_t new_space_allocation_throughput_in_bytes_per_ms) {
size_t new_space_allocation_limit =
kMaxFrameRenderingIdleTime * scavenge_speed_in_bytes_per_ms;
// If the limit is larger than the new space size, then scavenging used to be
// really fast. We can take advantage of the whole new space.
if (new_space_allocation_limit > new_space_size) {
new_space_allocation_limit = new_space_size;
}
// We do not know the allocation throughput before the first Scavenge.
// TODO(hpayer): Estimate allocation throughput before the first Scavenge.
if (new_space_allocation_throughput_in_bytes_per_ms == 0) {
new_space_allocation_limit =
static_cast<size_t>(new_space_size * kConservativeTimeRatio);
} else {
// We have to trigger scavenge before we reach the end of new space.
new_space_allocation_limit -=
new_space_allocation_throughput_in_bytes_per_ms *
kMaxFrameRenderingIdleTime;
}
if (scavenge_speed_in_bytes_per_ms == 0) {
scavenge_speed_in_bytes_per_ms = kInitialConservativeScavengeSpeed;
}
if (new_space_allocation_limit <= used_new_space_size) {
if (used_new_space_size / scavenge_speed_in_bytes_per_ms <=
idle_time_in_ms) {
return true;
}
}
return false;
}
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 >=
EstimateMarkCompactTime(size_of_objects,
mark_compact_speed_in_bytes_per_ms);
}
// 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 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.
// (3) If there is currently no MarkCompact idle round going on, we start a
// new idle round if enough garbage was created or we received a context
// disposal event. Otherwise we do not perform garbage collection to keep
// system utilization low.
// (4) If incremental marking is done, we perform a full garbage collection
// if context was disposed or if we are allowed to still do full garbage
// collections during this idle round or if we are not allowed to start
// incremental marking. Otherwise we do not perform garbage collection to
// keep system utilization low.
// (5) If sweeping is in progress and we received a large enough idle time
// request, we finalize sweeping here.
// (6) If incremental marking is in progress, we perform a marking step. Note,
// that this currently may trigger a full garbage collection.
GCIdleTimeAction GCIdleTimeHandler::Compute(size_t idle_time_in_ms,
HeapState heap_state) {
if (idle_time_in_ms == 0) {
if (heap_state.incremental_marking_stopped) {
if (heap_state.size_of_objects < kSmallHeapSize &&
heap_state.contexts_disposed > 0) {
return GCIdleTimeAction::FullGC();
}
}
return GCIdleTimeAction::Nothing();
}
if (ShouldDoScavenge(
idle_time_in_ms, heap_state.new_space_capacity,
heap_state.used_new_space_size,
heap_state.scavenge_speed_in_bytes_per_ms,
heap_state.new_space_allocation_throughput_in_bytes_per_ms)) {
return GCIdleTimeAction::Scavenge();
}
if (IsMarkCompactIdleRoundFinished()) {
if (EnoughGarbageSinceLastIdleRound() || heap_state.contexts_disposed > 0) {
StartIdleRound();
} else {
return GCIdleTimeAction::Done();
}
}
if (heap_state.incremental_marking_stopped) {
// TODO(jochen): Remove context disposal dependant logic.
if (ShouldDoMarkCompact(idle_time_in_ms, heap_state.size_of_objects,
heap_state.mark_compact_speed_in_bytes_per_ms) ||
(heap_state.size_of_objects < kSmallHeapSize &&
heap_state.contexts_disposed > 0)) {
// If there are no more than two GCs left in this idle round and we are
// allowed to do a full GC, then make those GCs full in order to compact
// the code space.
// TODO(ulan): Once we enable code compaction for incremental marking, we
// can get rid of this special case and always start incremental marking.
int remaining_mark_sweeps =
kMaxMarkCompactsInIdleRound - mark_compacts_since_idle_round_started_;
if (heap_state.contexts_disposed > 0 ||
(idle_time_in_ms > kMaxFrameRenderingIdleTime &&
(remaining_mark_sweeps <= 2 ||
!heap_state.can_start_incremental_marking))) {
return GCIdleTimeAction::FullGC();
}
}
if (!heap_state.can_start_incremental_marking) {
return GCIdleTimeAction::Nothing();
}
}
// TODO(hpayer): Estimate finalize sweeping time.
if (heap_state.sweeping_in_progress &&
idle_time_in_ms >= kMinTimeForFinalizeSweeping) {
return GCIdleTimeAction::FinalizeSweeping();
}
if (heap_state.incremental_marking_stopped &&
!heap_state.can_start_incremental_marking) {
return GCIdleTimeAction::Nothing();
}
size_t step_size = EstimateMarkingStepSize(
idle_time_in_ms, heap_state.incremental_marking_speed_in_bytes_per_ms);
return GCIdleTimeAction::IncrementalMarking(step_size);
}
}
}
|
