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 <poll.h> 21 #include <sys/types.h> 22 23 #include <memory> 24 #include <string> 25 26 #include <base/macros.h> 27 28 #include "perf_event.h" 29 30 struct PerfCounter { 31 uint64_t value; // The value of the event specified by the perf_event_file. 32 uint64_t time_enabled; // The enabled time. 33 uint64_t time_running; // The running time. 34 uint64_t id; // The id of the perf_event_file. 35 }; 36 37 // EventFd represents an opened perf_event_file. 38 class EventFd { 39 public: 40 static std::unique_ptr<EventFd> OpenEventFileForProcess(const perf_event_attr& attr, pid_t pid); 41 static std::unique_ptr<EventFd> OpenEventFileForCpu(const perf_event_attr& attr, int cpu); 42 static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr, pid_t pid, int cpu); 43 44 ~EventFd(); 45 46 // Give information about this perf_event_file, like (event_name, pid, cpu). 47 std::string Name() const; 48 49 uint64_t Id() const; 50 51 // It tells the kernel to start counting and recording events specified by this file. 52 bool EnableEvent(); 53 54 // It tells the kernel to stop counting and recording events specified by this file. 55 bool DisableEvent(); 56 57 bool ReadCounter(PerfCounter* counter) const; 58 59 // Call mmap() for this perf_event_file, so we can read sampled records from mapped area. 60 // mmap_pages should be power of 2. 61 bool MmapContent(size_t mmap_pages); 62 63 // When the kernel writes new sampled records to the mapped area, we can get them by returning 64 // the start address and size of the data. 65 size_t GetAvailableMmapData(char** pdata); 66 67 // Discard how much data we have read, so the kernel can reuse this part of mapped area to store 68 // new data. 69 void DiscardMmapData(size_t discard_size); 70 71 // Prepare pollfd for poll() to wait on available mmap_data. 72 void PreparePollForMmapData(pollfd* poll_fd); 73 74 private: 75 EventFd(int perf_event_fd, const std::string& event_name, pid_t pid, int cpu) 76 : perf_event_fd_(perf_event_fd), 77 id_(0), 78 event_name_(event_name), 79 pid_(pid), 80 cpu_(cpu), 81 mmap_addr_(nullptr), 82 mmap_len_(0) { 83 } 84 85 int perf_event_fd_; 86 mutable uint64_t id_; 87 const std::string event_name_; 88 pid_t pid_; 89 int cpu_; 90 91 void* mmap_addr_; 92 size_t mmap_len_; 93 perf_event_mmap_page* mmap_metadata_page_; // The first page of mmap_area. 94 char* mmap_data_buffer_; // Starts from the second page of mmap_area, containing records written 95 // by then kernel. 96 size_t mmap_data_buffer_size_; 97 98 DISALLOW_COPY_AND_ASSIGN(EventFd); 99 }; 100 101 #endif // SIMPLE_PERF_EVENT_FD_H_ 102
