1// Copyright 2012 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//
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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
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11//       with the distribution.
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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
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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
34namespace v8 {
35namespace internal {
36
37class Isolate;
38class JSFunction;
39class Object;
40class Semaphore;
41
42class RuntimeProfiler {
43 public:
44  explicit RuntimeProfiler(Isolate* isolate);
45
46  static void GlobalSetup();
47
48  static inline bool IsEnabled() {
49    ASSERT(has_been_globally_set_up_);
50    return enabled_;
51  }
52
53  void OptimizeNow();
54
55  void NotifyTick();
56
57  void SetUp();
58  void Reset();
59  void TearDown();
60
61  Object** SamplerWindowAddress();
62  int SamplerWindowSize();
63
64  void NotifyICChanged() { any_ic_changed_ = true; }
65
66  void NotifyCodeGenerated(int generated_code_size) {
67    if (FLAG_watch_ic_patching) {
68      code_generated_ = true;
69      total_code_generated_ += generated_code_size;
70    }
71  }
72
73  // Rate limiting support.
74
75  // VM thread interface.
76  //
77  // Called by isolates when their states change.
78  static inline void IsolateEnteredJS(Isolate* isolate);
79  static inline void IsolateExitedJS(Isolate* isolate);
80
81  // Profiler thread interface.
82  //
83  // IsSomeIsolateInJS():
84  // The profiler thread can query whether some isolate is currently
85  // running JavaScript code.
86  //
87  // WaitForSomeIsolateToEnterJS():
88  // When no isolates are running JavaScript code for some time the
89  // profiler thread suspends itself by calling the wait function. The
90  // wait function returns true after it waited or false immediately.
91  // While the function was waiting the profiler may have been
92  // disabled so it *must check* whether it is allowed to continue.
93  static bool IsSomeIsolateInJS();
94  static bool WaitForSomeIsolateToEnterJS();
95
96  // Stops the runtime profiler thread when profiling support is being
97  // turned off.
98  static void StopRuntimeProfilerThreadBeforeShutdown(Thread* thread);
99
100  void UpdateSamplesAfterScavenge();
101  void RemoveDeadSamples();
102  void UpdateSamplesAfterCompact(ObjectVisitor* visitor);
103
104  void AttemptOnStackReplacement(JSFunction* function);
105
106 private:
107  static const int kSamplerWindowSize = 16;
108
109  static void HandleWakeUp(Isolate* isolate);
110
111  void Optimize(JSFunction* function, const char* reason);
112
113  void ClearSampleBuffer();
114
115  void ClearSampleBufferNewSpaceEntries();
116
117  int LookupSample(JSFunction* function);
118
119  void AddSample(JSFunction* function, int weight);
120
121  Isolate* isolate_;
122
123  int sampler_threshold_;
124  int sampler_threshold_size_factor_;
125  int sampler_ticks_until_threshold_adjustment_;
126
127  Object* sampler_window_[kSamplerWindowSize];
128  int sampler_window_position_;
129  int sampler_window_weight_[kSamplerWindowSize];
130
131  bool any_ic_changed_;
132  bool code_generated_;
133  int total_code_generated_;
134
135  // Possible state values:
136  //   -1            => the profiler thread is waiting on the semaphore
137  //   0 or positive => the number of isolates running JavaScript code.
138  static Atomic32 state_;
139
140#ifdef DEBUG
141  static bool has_been_globally_set_up_;
142#endif
143  static bool enabled_;
144};
145
146
147// Rate limiter intended to be used in the profiler thread.
148class RuntimeProfilerRateLimiter BASE_EMBEDDED {
149 public:
150  RuntimeProfilerRateLimiter() {}
151
152  // Suspends the current thread (which must be the profiler thread)
153  // when not executing JavaScript to minimize CPU usage. Returns
154  // whether the thread was suspended (and so must check whether
155  // profiling is still active.)
156  //
157  // Does nothing when runtime profiling is not enabled.
158  bool SuspendIfNecessary();
159
160 private:
161  DISALLOW_COPY_AND_ASSIGN(RuntimeProfilerRateLimiter);
162};
163
164
165// Implementation of RuntimeProfiler inline functions.
166
167void RuntimeProfiler::IsolateEnteredJS(Isolate* isolate) {
168  Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, 1);
169  if (new_state == 0) {
170    // Just incremented from -1 to 0. -1 can only be set by the
171    // profiler thread before it suspends itself and starts waiting on
172    // the semaphore.
173    HandleWakeUp(isolate);
174  }
175  ASSERT(new_state >= 0);
176}
177
178
179void RuntimeProfiler::IsolateExitedJS(Isolate* isolate) {
180  Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, -1);
181  ASSERT(new_state >= 0);
182  USE(new_state);
183}
184
185} }  // namespace v8::internal
186
187#endif  // V8_RUNTIME_PROFILER_H_
188