1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef SIMPLE_PERF_EVENT_FD_H_ 18 #define SIMPLE_PERF_EVENT_FD_H_ 19 20 #include <sys/types.h> 21 22 #include <memory> 23 #include <string> 24 #include <vector> 25 26 #include <android-base/macros.h> 27 28 #include "IOEventLoop.h" 29 #include "perf_event.h" 30 31 struct PerfCounter { 32 uint64_t value; // The value of the event specified by the perf_event_file. 33 uint64_t time_enabled; // The enabled time. 34 uint64_t time_running; // The running time. 35 uint64_t id; // The id of the perf_event_file. 36 }; 37 38 // EventFd represents an opened perf_event_file. 39 class EventFd { 40 public: 41 static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr, 42 pid_t tid, int cpu, 43 EventFd* group_event_fd, 44 bool report_error = true); 45 46 virtual ~EventFd(); 47 48 // Give information about this perf_event_file, like (event_name, tid, cpu). 49 std::string Name() const; 50 51 uint64_t Id() const; 52 ThreadId()53 pid_t ThreadId() const { return tid_; } 54 Cpu()55 int Cpu() const { return cpu_; } 56 attr()57 const perf_event_attr& attr() const { return attr_; } 58 59 // It tells the kernel to start counting and recording events specified by 60 // this file. 61 bool SetEnableEvent(bool enable); 62 63 bool ReadCounter(PerfCounter* counter); 64 65 // Create mapped buffer used to receive records sent by the kernel. 66 // mmap_pages should be power of 2. 67 virtual bool CreateMappedBuffer(size_t mmap_pages, bool report_error); 68 69 // Share the mapped buffer used by event_fd. The two EventFds should monitor 70 // the same event on the same cpu, but have different thread ids. 71 bool ShareMappedBuffer(const EventFd& event_fd, bool report_error); 72 HasMappedBuffer()73 bool HasMappedBuffer() const { return mmap_data_buffer_size_ != 0; } GetMappedBuffer(size_t & buffer_size)74 char* GetMappedBuffer(size_t& buffer_size) { 75 buffer_size = mmap_data_buffer_size_; 76 return mmap_data_buffer_; 77 } 78 79 virtual void DestroyMappedBuffer(); 80 81 // Return available data in the kernel buffer. 82 std::vector<char> GetAvailableMmapData(); 83 // Return the size of available data in the buffer, and set data_pos to the first available data 84 // position in mmap_data_buffer_. 85 virtual size_t GetAvailableMmapDataSize(size_t& data_pos); 86 // Discard the size of the data we have read, so the kernel can reuse the space for new data. 87 virtual void DiscardMmapData(size_t discard_size); 88 89 // [callback] is called when there is data available in the mapped buffer. 90 virtual bool StartPolling(IOEventLoop& loop, const std::function<bool()>& callback); 91 virtual bool StopPolling(); 92 93 protected: EventFd(const perf_event_attr & attr,int perf_event_fd,const std::string & event_name,pid_t tid,int cpu)94 EventFd(const perf_event_attr& attr, int perf_event_fd, 95 const std::string& event_name, pid_t tid, int cpu) 96 : attr_(attr), 97 perf_event_fd_(perf_event_fd), 98 id_(0), 99 event_name_(event_name), 100 tid_(tid), 101 cpu_(cpu), 102 mmap_addr_(nullptr), 103 mmap_len_(0), 104 mmap_metadata_page_(nullptr), 105 mmap_data_buffer_(nullptr), 106 mmap_data_buffer_size_(0), 107 ioevent_ref_(nullptr), 108 last_counter_value_(0) {} 109 110 bool InnerReadCounter(PerfCounter* counter) const; 111 112 const perf_event_attr attr_; 113 int perf_event_fd_; 114 mutable uint64_t id_; 115 const std::string event_name_; 116 pid_t tid_; 117 int cpu_; 118 119 void* mmap_addr_; 120 size_t mmap_len_; 121 perf_event_mmap_page* mmap_metadata_page_; // The first page of mmap_area. 122 char* mmap_data_buffer_; // Starting from the second page of mmap_area, 123 // containing records written by then kernel. 124 size_t mmap_data_buffer_size_; 125 126 IOEventRef ioevent_ref_; 127 128 // Used by atrace to generate value difference between two ReadCounter() calls. 129 uint64_t last_counter_value_; 130 131 DISALLOW_COPY_AND_ASSIGN(EventFd); 132 }; 133 134 bool IsEventAttrSupported(const perf_event_attr& attr); 135 136 #endif // SIMPLE_PERF_EVENT_FD_H_ 137