2 * Copyright (C) 2015 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #ifndef SIMPLE_PERF_EVENT_FD_H_
18 #define SIMPLE_PERF_EVENT_FD_H_
21 #include <sys/types.h>
27 #include <android-base/macros.h>
29 #include "perf_event.h"
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.
38 // EventFd represents an opened perf_event_file.
41 static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr, pid_t tid, int cpu,
42 bool report_error = true);
48 pid_t ThreadId() const {
56 bool ReadCounter(PerfCounter* counter) const;
58 // Call mmap() for this perf_event_file, so we can read sampled records from mapped area.
59 // mmap_pages should be power of 2.
60 bool MmapContent(size_t mmap_pages);
62 // When the kernel writes new sampled records to the mapped area, we can get them by returning
63 // the start address and size of the data.
64 size_t GetAvailableMmapData(char** pdata);
66 // Prepare pollfd for poll() to wait on available mmap_data.
67 void PreparePollForMmapData(pollfd* poll_fd);
70 EventFd(int perf_event_fd, const std::string& event_name, pid_t tid, int cpu)
71 : perf_event_fd_(perf_event_fd),
73 event_name_(event_name),
80 // Give information about this perf_event_file, like (event_name, tid, cpu).
81 std::string Name() const;
83 // Discard how much data we have read, so the kernel can reuse this part of mapped area to store
85 void DiscardMmapData(size_t discard_size);
89 const std::string event_name_;
95 perf_event_mmap_page* mmap_metadata_page_; // The first page of mmap_area.
96 char* mmap_data_buffer_; // Starts from the second page of mmap_area, containing records written
98 size_t mmap_data_buffer_size_;
100 // As mmap_data_buffer is a ring buffer, it is possible that one record is wrapped at the
101 // end of the buffer. So we need to copy records from mmap_data_buffer to data_process_buffer
102 // before processing them.
103 static std::vector<char> data_process_buffer_;
105 DISALLOW_COPY_AND_ASSIGN(EventFd);
108 bool IsEventAttrSupportedByKernel(perf_event_attr attr);
110 #endif // SIMPLE_PERF_EVENT_FD_H_