/* * Copyright (C) 2015 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef SIMPLE_PERF_EVENT_FD_H_ #define SIMPLE_PERF_EVENT_FD_H_ #include <poll.h> #include <sys/types.h> #include <memory> #include <string> #include <base/macros.h> #include "perf_event.h" struct PerfCounter { uint64_t value; // The value of the event specified by the perf_event_file. uint64_t time_enabled; // The enabled time. uint64_t time_running; // The running time. uint64_t id; // The id of the perf_event_file. }; // EventFd represents an opened perf_event_file. class EventFd { public: static std::unique_ptr<EventFd> OpenEventFileForProcess(const perf_event_attr& attr, pid_t pid); static std::unique_ptr<EventFd> OpenEventFileForCpu(const perf_event_attr& attr, int cpu); static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr, pid_t pid, int cpu); ~EventFd(); // Give information about this perf_event_file, like (event_name, pid, cpu). std::string Name() const; uint64_t Id() const; // It tells the kernel to start counting and recording events specified by this file. bool EnableEvent(); // It tells the kernel to stop counting and recording events specified by this file. bool DisableEvent(); bool ReadCounter(PerfCounter* counter) const; // Call mmap() for this perf_event_file, so we can read sampled records from mapped area. // mmap_pages should be power of 2. bool MmapContent(size_t mmap_pages); // When the kernel writes new sampled records to the mapped area, we can get them by returning // the start address and size of the data. size_t GetAvailableMmapData(char** pdata); // Discard how much data we have read, so the kernel can reuse this part of mapped area to store // new data. void DiscardMmapData(size_t discard_size); // Prepare pollfd for poll() to wait on available mmap_data. void PreparePollForMmapData(pollfd* poll_fd); private: EventFd(int perf_event_fd, const std::string& event_name, pid_t pid, int cpu) : perf_event_fd_(perf_event_fd), id_(0), event_name_(event_name), pid_(pid), cpu_(cpu), mmap_addr_(nullptr), mmap_len_(0) { } int perf_event_fd_; mutable uint64_t id_; const std::string event_name_; pid_t pid_; int cpu_; void* mmap_addr_; size_t mmap_len_; perf_event_mmap_page* mmap_metadata_page_; // The first page of mmap_area. char* mmap_data_buffer_; // Starts from the second page of mmap_area, containing records written // by then kernel. size_t mmap_data_buffer_size_; DISALLOW_COPY_AND_ASSIGN(EventFd); }; #endif // SIMPLE_PERF_EVENT_FD_H_