94 lines
2.6 KiB
C++
94 lines
2.6 KiB
C++
// https://github.com/WojciechMula/toys/blob/master/000helpers/linux-perf-events.h
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#pragma once
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#ifdef __linux__
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#include <asm/unistd.h> // for __NR_perf_event_open
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#include <linux/perf_event.h> // for perf event constants
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#include <sys/ioctl.h> // for ioctl
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#include <unistd.h> // for syscall
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#include <cerrno> // for errno
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#include <cstring> // for memset
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#include <stdexcept>
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#include <iostream>
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#include <vector>
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template <int TYPE = PERF_TYPE_HARDWARE> class LinuxEvents {
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int fd;
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bool working;
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perf_event_attr attribs;
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int num_events;
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std::vector<uint64_t> temp_result_vec;
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std::vector<uint64_t> ids;
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public:
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explicit LinuxEvents(std::vector<int> config_vec) : fd(0), working(true) {
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memset(&attribs, 0, sizeof(attribs));
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attribs.type = TYPE;
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attribs.size = sizeof(attribs);
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attribs.disabled = 1;
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attribs.exclude_kernel = 1;
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attribs.exclude_hv = 1;
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attribs.sample_period = 0;
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attribs.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
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const int pid = 0; // the current process
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const int cpu = -1; // all CPUs
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const unsigned long flags = 0;
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int group = -1; // no group
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num_events = config_vec.size();
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ids.resize(config_vec.size());
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uint32_t i = 0;
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for (auto config : config_vec) {
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attribs.config = config;
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fd = syscall(__NR_perf_event_open, &attribs, pid, cpu, group, flags);
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if (fd == -1) {
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report_error("perf_event_open");
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}
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ioctl(fd, PERF_EVENT_IOC_ID, &ids[i++]);
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if (group == -1) {
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group = fd;
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}
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}
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temp_result_vec.resize(num_events * 2 + 1);
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}
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~LinuxEvents() { close(fd); }
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inline void start() {
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if (ioctl(fd, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP) == -1) {
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report_error("ioctl(PERF_EVENT_IOC_RESET)");
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}
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if (ioctl(fd, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP) == -1) {
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report_error("ioctl(PERF_EVENT_IOC_ENABLE)");
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}
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}
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inline void end(std::vector<unsigned long long> &results) {
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if (ioctl(fd, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP) == -1) {
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report_error("ioctl(PERF_EVENT_IOC_DISABLE)");
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}
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if (read(fd, temp_result_vec.data(), temp_result_vec.size() * 8) == -1) {
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report_error("read");
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}
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// our actual results are in slots 1,3,5, ... of this structure
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// we really should be checking our ids obtained earlier to be safe
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for (uint32_t i = 1; i < temp_result_vec.size(); i += 2) {
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results[i / 2] = temp_result_vec[i];
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}
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}
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private:
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void report_error(const std::string &context) {
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if (working)
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std::cerr << (context + ": " + std::string(strerror(errno))) << std::endl;
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working = false;
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}
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};
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#endif
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