1 /* 2 * Copyright (C) 2018 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_FTRACE_READER_FTRACE_CONFIG_MUXER_H_ 18 #define SRC_FTRACE_READER_FTRACE_CONFIG_MUXER_H_ 19 20 #include "perfetto/ftrace_reader/ftrace_controller.h" 21 #include "src/ftrace_reader/ftrace_procfs.h" 22 23 namespace perfetto { 24 25 // Ftrace is a bunch of globaly modifiable persistent state. 26 // Given a number of FtraceConfig's we need to find the best union of all 27 // the settings to make eveyone happy while also watching out for anybody 28 // messing with the ftrace settings at the same time as us. 29 30 // Specifically FtraceConfigMuxer takes in a *requested* FtraceConfig 31 // (|RequestConfig|), makes a best effort attempt to modify the ftrace 32 // debugfs files to honor those settings without interupting other perfetto 33 // traces already in progress or other users of ftrace, then returns an 34 // FtraceConfigId representing that config or zero on failure. 35 36 // To see which settings we actually managed to set you can call |GetConfig| 37 // and when you are finished with a config you can signal that with 38 // |RemoveConfig|. 39 class FtraceConfigMuxer { 40 public: 41 // The FtraceConfigMuxer and ProtoTranslationTable 42 // should outlive this instance. 43 FtraceConfigMuxer(FtraceProcfs* ftrace, const ProtoTranslationTable* table); 44 virtual ~FtraceConfigMuxer(); 45 46 // Ask FtraceConfigMuxer to adjust ftrace procfs settings to 47 // match the requested config. Returns an id to manage this 48 // config or zero on failure. 49 // This is best effort. FtraceConfigMuxer may not be able to adjust the 50 // buffer size right now. Events may be missing or there may be extra events 51 // (if you enable an atrace catagory we try to give you the matching events). 52 // If someone else is tracing we won't touch atrace (since it resets the 53 // buffer). 54 // To see the config you ended up with use |GetConfig|. 55 FtraceConfigId RequestConfig(const FtraceConfig& request); 56 57 // Undo changes for the given config. Returns false iff the id is 0 58 // or already removed. 59 bool RemoveConfig(FtraceConfigId id); 60 61 // public for testing 62 void SetupClockForTesting(const FtraceConfig& request) { 63 SetupClock(request); 64 } 65 66 const FtraceConfig* GetConfig(FtraceConfigId id); 67 68 private: 69 struct FtraceState { 70 std::set<std::string> ftrace_events; 71 std::set<std::string> atrace_categories; 72 std::set<std::string> atrace_apps; 73 bool tracing_on = false; 74 bool atrace_on = false; 75 size_t cpu_buffer_size_pages = 0; 76 }; 77 78 FtraceConfigMuxer(const FtraceConfigMuxer&) = delete; 79 FtraceConfigMuxer& operator=(const FtraceConfigMuxer&) = delete; 80 81 void SetupClock(const FtraceConfig& request); 82 void SetupBufferSize(const FtraceConfig& request); 83 void UpdateAtrace(const FtraceConfig& request); 84 void DisableAtrace(); 85 86 FtraceConfigId GetNextId(); 87 88 FtraceConfigId last_id_ = 1; 89 FtraceProcfs* ftrace_; 90 const ProtoTranslationTable* table_; 91 92 FtraceState current_state_; 93 std::map<FtraceConfigId, FtraceConfig> configs_; 94 }; 95 96 std::set<std::string> GetFtraceEvents(const FtraceConfig& request, 97 const ProtoTranslationTable*); 98 size_t ComputeCpuBufferSizeInPages(size_t requested_buffer_size_kb); 99 100 } // namespace perfetto 101 102 #endif // SRC_FTRACE_READER_FTRACE_CONFIG_MUXER_H_ 103
