1 // Copyright 2013 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_SAMPLER_H_ 29 #define V8_SAMPLER_H_ 30 31 #include "atomicops.h" 32 #include "frames.h" 33 #include "v8globals.h" 34 35 namespace v8 { 36 namespace internal { 37 38 class Isolate; 39 40 // ---------------------------------------------------------------------------- 41 // Sampler 42 // 43 // A sampler periodically samples the state of the VM and optionally 44 // (if used for profiling) the program counter and stack pointer for 45 // the thread that created it. 46 47 struct RegisterState { RegisterStateRegisterState48 RegisterState() : pc(NULL), sp(NULL), fp(NULL) {} 49 Address pc; // Instruction pointer. 50 Address sp; // Stack pointer. 51 Address fp; // Frame pointer. 52 }; 53 54 // TickSample captures the information collected for each sample. 55 struct TickSample { TickSampleTickSample56 TickSample() 57 : state(OTHER), 58 pc(NULL), 59 external_callback(NULL), 60 frames_count(0), 61 has_external_callback(false), 62 top_frame_type(StackFrame::NONE) {} 63 void Init(Isolate* isolate, const RegisterState& state); 64 StateTag state; // The state of the VM. 65 Address pc; // Instruction pointer. 66 union { 67 Address tos; // Top stack value (*sp). 68 Address external_callback; 69 }; 70 static const int kMaxFramesCount = 64; 71 Address stack[kMaxFramesCount]; // Call stack. 72 int frames_count : 8; // Number of captured frames. 73 bool has_external_callback : 1; 74 StackFrame::Type top_frame_type : 4; 75 }; 76 77 class Sampler { 78 public: 79 // Initializes the Sampler support. Called once at VM startup. 80 static void SetUp(); 81 static void TearDown(); 82 83 // Initialize sampler. 84 Sampler(Isolate* isolate, int interval); 85 virtual ~Sampler(); 86 isolate()87 Isolate* isolate() const { return isolate_; } interval()88 int interval() const { return interval_; } 89 90 // Performs stack sampling. 91 void SampleStack(const RegisterState& regs); 92 93 // Start and stop sampler. 94 void Start(); 95 void Stop(); 96 97 // Whether the sampling thread should use this Sampler for CPU profiling? IsProfiling()98 bool IsProfiling() const { 99 return NoBarrier_Load(&profiling_) > 0 && 100 !NoBarrier_Load(&has_processing_thread_); 101 } 102 void IncreaseProfilingDepth(); 103 void DecreaseProfilingDepth(); 104 105 // Whether the sampler is running (that is, consumes resources). IsActive()106 bool IsActive() const { return NoBarrier_Load(&active_); } 107 108 void DoSample(); 109 // If true next sample must be initiated on the profiler event processor 110 // thread right after latest sample is processed. SetHasProcessingThread(bool value)111 void SetHasProcessingThread(bool value) { 112 NoBarrier_Store(&has_processing_thread_, value); 113 } 114 115 // Used in tests to make sure that stack sampling is performed. js_and_external_sample_count()116 unsigned js_and_external_sample_count() const { 117 return js_and_external_sample_count_; 118 } StartCountingSamples()119 void StartCountingSamples() { 120 is_counting_samples_ = true; 121 js_and_external_sample_count_ = 0; 122 } 123 124 class PlatformData; platform_data()125 PlatformData* platform_data() const { return data_; } 126 127 protected: 128 // This method is called for each sampling period with the current 129 // program counter. 130 virtual void Tick(TickSample* sample) = 0; 131 132 private: SetActive(bool value)133 void SetActive(bool value) { NoBarrier_Store(&active_, value); } 134 135 Isolate* isolate_; 136 const int interval_; 137 Atomic32 profiling_; 138 Atomic32 has_processing_thread_; 139 Atomic32 active_; 140 PlatformData* data_; // Platform specific data. 141 bool is_counting_samples_; 142 // Counts stack samples taken in JS VM state. 143 unsigned js_and_external_sample_count_; 144 DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler); 145 }; 146 147 148 } } // namespace v8::internal 149 150 #endif // V8_SAMPLER_H_ 151