1 /* 2 * Copyright (C) 2017 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 SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 18 #define SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 19 20 #include <memory> 21 #include <set> 22 #include <string> 23 24 #include "perfetto/base/scoped_file.h" 25 26 namespace perfetto { 27 28 class FtraceProcfs { 29 public: 30 static std::unique_ptr<FtraceProcfs> Create(const std::string& root); 31 static int g_kmesg_fd; 32 33 explicit FtraceProcfs(const std::string& root); 34 virtual ~FtraceProcfs(); 35 36 // Enable the event under with the given |group| and |name|. 37 bool EnableEvent(const std::string& group, const std::string& name); 38 39 // Disable the event under with the given |group| and |name|. 40 bool DisableEvent(const std::string& group, const std::string& name); 41 42 // Disable all events by writing to the global enable file. 43 bool DisableAllEvents(); 44 45 // Read the format for event with the given |group| and |name|. 46 // virtual for testing. 47 virtual std::string ReadEventFormat(const std::string& group, 48 const std::string& name) const; 49 50 virtual std::string ReadPageHeaderFormat() const; 51 52 // Read the "/per_cpu/cpuXX/stats" file for the given |cpu|. 53 std::string ReadCpuStats(size_t cpu) const; 54 55 // Set ftrace buffer size in pages. 56 // This size is *per cpu* so for the total size you have to multiply 57 // by the number of CPUs. 58 bool SetCpuBufferSizeInPages(size_t pages); 59 60 // Returns the number of CPUs. 61 // This will match the number of tracing/per_cpu/cpuXX directories. 62 size_t virtual NumberOfCpus() const; 63 64 // Clears the trace buffers for all CPUs. Blocks until this is done. 65 void ClearTrace(); 66 67 // Writes the string |str| as an event into the trace buffer. 68 bool WriteTraceMarker(const std::string& str); 69 70 // Enable tracing. 71 bool EnableTracing(); 72 73 // Disables tracing, does not clear the buffer. 74 bool DisableTracing(); 75 76 // Enabls/disables tracing, does not clear the buffer. 77 bool SetTracingOn(bool enable); 78 79 // Returns true iff tracing is enabled. 80 // Necessarily racy: another program could enable/disable tracing at any 81 // point. 82 bool IsTracingEnabled(); 83 84 // Set the clock. |clock_name| should be one of the names returned by 85 // AvailableClocks. Setting the clock clears the buffer. 86 bool SetClock(const std::string& clock_name); 87 88 // Get the currently set clock. 89 std::string GetClock(); 90 91 // Get all the avaiable clocks. 92 std::set<std::string> AvailableClocks(); 93 94 // Open the raw pipe for |cpu|. 95 virtual base::ScopedFile OpenPipeForCpu(size_t cpu); 96 97 virtual const std::set<std::string> GetEventNamesForGroup( 98 const std::string& path) const; 99 100 protected: 101 // virtual and public for testing. 102 virtual bool WriteToFile(const std::string& path, const std::string& str); 103 virtual bool AppendToFile(const std::string& path, const std::string& str); 104 virtual bool ClearFile(const std::string& path); 105 virtual char ReadOneCharFromFile(const std::string& path); 106 virtual std::string ReadFileIntoString(const std::string& path) const; 107 108 private: 109 // Checks the trace file is present at the given root path. 110 static bool CheckRootPath(const std::string& root); 111 112 bool WriteNumberToFile(const std::string& path, size_t value); 113 114 const std::string root_; 115 }; 116 117 } // namespace perfetto 118 119 #endif // SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 120
