1 // Copyright 2010 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28 #ifndef V8_RUNTIME_PROFILER_H_
29 #define V8_RUNTIME_PROFILER_H_
30
31 #include "allocation.h"
32 #include "atomicops.h"
33
34 namespace v8 {
35 namespace internal {
36
37 class Isolate;
38 class JSFunction;
39 class Object;
40 class PendingListNode;
41 class Semaphore;
42
43 class RuntimeProfiler {
44 public:
45 explicit RuntimeProfiler(Isolate* isolate);
46
47 static void GlobalSetup();
48
IsEnabled()49 static inline bool IsEnabled() {
50 ASSERT(has_been_globally_setup_);
51 return enabled_;
52 }
53
54 void OptimizeNow();
55 void OptimizeSoon(JSFunction* function);
56
57 void NotifyTick();
58
59 void Setup();
60 void Reset();
61 void TearDown();
62
63 Object** SamplerWindowAddress();
64 int SamplerWindowSize();
65
66 // Rate limiting support.
67
68 // VM thread interface.
69 //
70 // Called by isolates when their states change.
71 static inline void IsolateEnteredJS(Isolate* isolate);
72 static inline void IsolateExitedJS(Isolate* isolate);
73
74 // Profiler thread interface.
75 //
76 // IsSomeIsolateInJS():
77 // The profiler thread can query whether some isolate is currently
78 // running JavaScript code.
79 //
80 // WaitForSomeIsolateToEnterJS():
81 // When no isolates are running JavaScript code for some time the
82 // profiler thread suspends itself by calling the wait function. The
83 // wait function returns true after it waited or false immediately.
84 // While the function was waiting the profiler may have been
85 // disabled so it *must check* whether it is allowed to continue.
86 static bool IsSomeIsolateInJS();
87 static bool WaitForSomeIsolateToEnterJS();
88
89 // When shutting down we join the profiler thread. Doing so while
90 // it's waiting on a semaphore will cause a deadlock, so we have to
91 // wake it up first.
92 static void WakeUpRuntimeProfilerThreadBeforeShutdown();
93
94 void UpdateSamplesAfterScavenge();
95 void RemoveDeadSamples();
96 void UpdateSamplesAfterCompact(ObjectVisitor* visitor);
97
98 private:
99 static const int kSamplerWindowSize = 16;
100 static const int kStateWindowSize = 128;
101
102 enum SamplerState {
103 IN_NON_JS_STATE = 0,
104 IN_JS_STATE = 1
105 };
106
107 static void HandleWakeUp(Isolate* isolate);
108
109 void Optimize(JSFunction* function, bool eager, int delay);
110
111 void AttemptOnStackReplacement(JSFunction* function);
112
113 void ClearSampleBuffer();
114
115 void ClearSampleBufferNewSpaceEntries();
116
117 int LookupSample(JSFunction* function);
118
119 void AddSample(JSFunction* function, int weight);
120
121 #ifdef ENABLE_LOGGING_AND_PROFILING
122 void UpdateStateRatio(SamplerState current_state);
123 #endif
124
125 Isolate* isolate_;
126
127 int sampler_threshold_;
128 int sampler_threshold_size_factor_;
129 int sampler_ticks_until_threshold_adjustment_;
130
131 // The ratio of ticks spent in JS code in percent.
132 Atomic32 js_ratio_;
133
134 Object* sampler_window_[kSamplerWindowSize];
135 int sampler_window_position_;
136 int sampler_window_weight_[kSamplerWindowSize];
137
138 // Support for pending 'optimize soon' requests.
139 PendingListNode* optimize_soon_list_;
140
141 SamplerState state_window_[kStateWindowSize];
142 int state_window_position_;
143 int state_window_ticks_;
144 int state_counts_[2];
145
146 // Possible state values:
147 // -1 => the profiler thread is waiting on the semaphore
148 // 0 or positive => the number of isolates running JavaScript code.
149 static Atomic32 state_;
150 static Semaphore* semaphore_;
151
152 #ifdef DEBUG
153 static bool has_been_globally_setup_;
154 #endif
155 static bool enabled_;
156 };
157
158
159 // Rate limiter intended to be used in the profiler thread.
160 class RuntimeProfilerRateLimiter BASE_EMBEDDED {
161 public:
RuntimeProfilerRateLimiter()162 RuntimeProfilerRateLimiter() : non_js_ticks_(0) { }
163
164 // Suspends the current thread (which must be the profiler thread)
165 // when not executing JavaScript to minimize CPU usage. Returns
166 // whether the thread was suspended (and so must check whether
167 // profiling is still active.)
168 //
169 // Does nothing when runtime profiling is not enabled.
170 bool SuspendIfNecessary();
171
172 private:
173 int non_js_ticks_;
174
175 DISALLOW_COPY_AND_ASSIGN(RuntimeProfilerRateLimiter);
176 };
177
178
179 // Implementation of RuntimeProfiler inline functions.
180
IsolateEnteredJS(Isolate * isolate)181 void RuntimeProfiler::IsolateEnteredJS(Isolate* isolate) {
182 Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, 1);
183 if (new_state == 0) {
184 // Just incremented from -1 to 0. -1 can only be set by the
185 // profiler thread before it suspends itself and starts waiting on
186 // the semaphore.
187 HandleWakeUp(isolate);
188 }
189 ASSERT(new_state >= 0);
190 }
191
192
IsolateExitedJS(Isolate * isolate)193 void RuntimeProfiler::IsolateExitedJS(Isolate* isolate) {
194 Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, -1);
195 ASSERT(new_state >= 0);
196 USE(new_state);
197 }
198
199 } } // namespace v8::internal
200
201 #endif // V8_RUNTIME_PROFILER_H_
202